Sweat Electrolyte Content and Fluid Balance in Elite Triathletes

Amy B. Mausser

B.A.H.S., Sheridan College, 2009

A Thesis Submitted in Partial Fulfillment of the Requirements for the Degree of Masters of Science at the University of Connecticut 2013

APPROVAL PAGE

Masters of Science Thesis

Sweat Electrolyte Content and Fluid Balance in Elite Triathletes

Presented by

Amy B. Mausser

Major Advisor ______Douglas J. Casa, PhD, ATC, FACSM,

Associate Advisor ______Lawrence E. Armstrong, PhD, FACSM

Associate Advisor ______Carl M. Maresh, PhD

PhD Mentor ______Riana R. Pryor, MS, ATC

University of Connecticut 2013

ABSTRACT

Elite triathletes’ sweat volume and electrolyte losses during exercise can be detrimental in a warm environment. PURPOSE: The aim of this study was to investigate urine and sweat electrolyte losses of male and female triathletes during endurance exercise in a warm environment. METHODS: Thirty five Timex sponsored triathletes (n = 20♂, 15♀: age 39 ± 12yr, 33 ± 6 yr; height 181 ± 6 cm, 171 ± 6 cm; weight 76.1 ± 7.0 kg, 60.1 ± 5.4 kg; fast half Ironman time 4:30 ± 0:40 hr:min, 5:09 ± 0:32 hr:min, respectively) completed a 43.4 ± 3.8 minute treadmill run or friction resisted cycle ergometer bike at their predicted half Ironman race pace in a heated environment (28.0 ± 0.5 ºC, 27.2 ± 4.9

% relative humidity). Before exercise each subject provided a urine sample and skin fold measures were taken. Percent dehydration was calculated using pre- and post-exercise nude body weights. Whole body wash-down (WBW) was performed using distilled, deionized water to determine sweat electrolyte content. Twenty-four hour urine was collected to calculate sodium and potassium losses. Twenty-four hour diet intake was recorded to calculate net balance. RESULTS: Sweat electrolyte losses during exercise differed between genders. Men had higher sweat rates and sweat loss than women (1.88 ±

0.38 L·h-1 vs 1.34 ± 0.36 L·h-1, p ≤ 0.001; 1.39 ± 0.31 L vs 0.95 ± 0.27 L, p ≤ 0.001), respectively. Men had greater sweat sodium loss (p=0.004; men: 60.3 ± 19.9 mEq vs women: 39.4 ± 19.9 mEq) and a greater rate of sweat sodium loss (p=0.010; 82.4 ± 26.6 mEq·hr-1 vs women: 56.5 ± 30.1 mEq·hr-1). Concentrations of sweat sodium and potassium did not differ between genders. Men had higher urine sodium mass than women (196.2 ± 80.1 mEq vs 117.5 ± 49.5 mEq, respectively, p=0.002). Net Balance differences were not found between male and female intake and loss of fluid and

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electrolytes. During the 24 hour dietary consumption, women consumed less water than men (3.026 ± 1.216 L vs 4.594 ± 2.824 L, respectively, p=0.036) and Na+ content

(3588.7 ± 1004.7 mg vs 5081.2 ± 2277.2 mg, respectively, p=0.017). CONCLUSION:

Sweat volume, electrolyte loss, urinary sodium loss and diet intake differed between male and female elite triathletes. When determining fluid and sodium replacement requirements in warm conditions for high level triathletes, men may need to replace more fluids and sodium at greater rates than women to remain homeostatic.

ACKNOWLEDGEMENTS

The past two years have been a truly amazing experience. Attending the

University of Connecticut has helped me grow and develop into a dynamic and distinctive individual. Working at Windham High School has helped me develop patience and perseverance. I would like to thank a couple people who have been a vital part in my development here at UConn.

Dr. Casa, who I first met on the phone and who enjoyed listening to my Canadian accent, was a vital asset to staying positive during the entire transition to a new country.

His support and encouragement helped me adjust to life here in Connecticut. He was the man behind the curtain who made this entire thesis become a reality. His advice and sometimes-scathing criticism gave me the skill set I needed to achieve as much as I have, and which I have endless thanks for. More than that, he has also opened many doors that will help me develop a long-lasting career in Athletic Training and as an athlete.

Dr. Armstrong and Dr. Maresh were essential in the completion of this thesis by providing thorough feedback and revisions. I am very thankful for their assistance in their higher knowledge and understanding of physiology. Their dedication to furthering my thesis has given me a greater appreciation for the investment needed to produce exceptional research and a concise analysis.

Rianna has been a vital part in completing this entire project from approval to data collection and manuscript writing. I am extremely thankful for all her guidance. She started as my constant mentor, helping me eliminate simple mistakes and slowly she helped me become an independent researcher. This was perhaps the most important stepping stone for the execution of this study.

I want to thank the Windham High School family, faculty, coaches and students for the many laughs and memorable moments during the past two years. The many new ever-lasting friendships that I have gained, I hope flourish and continue for many more.

Thank you to my classmates for adding some ease into the everyday journey through the past two years.

Lastly I want to thank my family and friends for their continuous support.

Without their encouragement and reassurance I would not have been able to keep an open-mind and focus through to the very end. Especially thank you to my parents for their love and constant support.

LIST OF TABLES

Table 4.1 Subject demographics from observational period

Table 4.2 Exercise data during 45min of exercise

Table 5.1 Finish time versus speed, body fat (%), and exercise speed

Table 5.2 Comparison of ten fastest versus ten slowest half -ironman finishers

Table 5.3 Sweat rate/loss, dehydration and consumption of fluids during 45min testing Table 5.4 Sweat and 24 hour urine electrolytes during laboratory testing

Table 5.5 Average loss of sweat electrolytes during a half-Ironman and full-Ironman distances Table 5.6 Relative sweat electrolyte loss during 45min testing

Table 5.7 Twenty four hour urine electrolytes during laboratory testing

Table 5.8 Fluid and electrolyte net balances during 24 hours of recording

Table 5.9 Net balances for nutrients and fluids consumed

Table 5.10 Nutritional values during 24 observational hours

Table 5.11 Sweat electrolyte loss in heat acclimatized triathletes

Table 5.12 Sweat electrolyte loss relative to exercise intensity during 45 min

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LIST OF FIGURES

Figure 1. Whole body net sodium balance (□,■) and whole body net cation balance (◊, ) vs. whole body net fluid balance 5 (□,◊) and 6 (■, ) h after end of volume repletion period. For net sodium balance, y = 59.75+ 0.28 x; R2 = 0.521. For net cation balance, y = -1.68+0.23x; R2 = 0.577. Points are mean values. Fitted lines are calculated from 6-h values only.18

Figure 2. Plasma sodium concentration during exercise in the heat in which fluid replacement was with either water (W) or a sodium containing sports drink, Gatorade (G). ANOVA demonstrated a significantly greater decrease with W (P= 0.0007).27

Figure 3. Sweat sensitivity of each heat stress test normalized for area under heating curve. Values are means ± SE. *Significantly different from all other treatments, P, 0.05–0.01.55

Figure 4. Whole body net fluid balance calculated from estimated sweat loss, volume of fluid ingested, and urine output over course of experiment. Pre- exercise urine sample is not included in these calculations. Points are mean values.18

Figure 6. Urine output over time. Pre-exercise sample has not been shown. Points are median values.18

Figure 6.1 Sweat and fluid consumption during exercise

Figure 6.2 Sweat electrolytes during laboratory testing Figure 6.3 Sweat electrolytes during laboratory testing

Figure 6.4 Twenty-four hour urine electrolytes during laboratory testing

Figure 6.5 Differences in male and female fluid turnover during testing

Figure 6.6 Net Balances of sodium, potassium and water during the 24 hour observational period

Figure 6.7 Carbohydrate, fat, protein dietary intake during 24 h nutrient record

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TABLE OF CONTENTS Page

APPROVAL PAGE…………………………………………………….……………..…..ii

ABSTRACT…………………………………………………………..………………….iii

ACKNOWLEDGEMENTS…………………...………………………..…………………v

LIST OF TABLES……………………………………………………………..…...……vii

LIST OF FIGURES………………………………………………………………….….viii

CHAPTER

1. REVIEW OF THE LITERATURE

Sweat and Urine Electrolyte Concentrations………………..……………...…1

Electrolyte Turnover……………..….…………..…..…………………….2

Plasma Osmolality…………………………………...……………………7

Electrolytes and Performance………………………………………...….10

Physiology of Hydration………………………………..……………………12

Hydration on Cell Function...... ………………………………………….12

Central Regulator System and its Effects on Fluid Shifts ….…………..14

Sweat Rate……………………………………………………………….15

Water Turnover……………………………………………………..……17

Core Temperature and Hydration………………………………………..20

Hydration changes during Exercise and Heat Stress…………………….23

Hydration and Performance………………………………………….…..24

Urine Excretion…………………………………………………………..27

Summary and Purpose of Study…………………………………………….29

REFERENCES…………………………………………………………………..30

2. INTRODUCTION…………………………………………………………...37

3. SCIENTIFIC RESEARCH METHODS

Subject Characteristics…………………………………………………...39

Preliminary Procedures…………………………………………………..40

Experimental Procedures………………………………………………...41

Post Exercise Procedures………………………………………………...42

Sodium Turnover Analysis………………………………………………43

Intensity Analysis………………………………………………………..44

Statistical Analyses………………………………………………………44

4. RESULTS……………………………………………………………………45

Sweat Measures………………………………………………………….46

Electrolyte Content Relative to Body Mass……………………………...49

Urine Measures…………………………………………………………..49

Electrolyte Turnover and Nutrient Content……………………………...51

Acclimatization…………………………………………………………..54

Exercise Intensity versus Electrolyte Loss………………………………54

5. DISCUSSION

Sweat Rate and Sweat Loss……………………………………………...56

Sweat Electrolyte Loss…………………………………………..………57

Half versus Full Ironman……………………………………………...…59

Electrolyte Turnover and Nutrient Content……………………………...60

Top Finishers versus Bottom Finishers………………………………….62

Exercise Intensity versus Electrolyte Loss………………………………65

Practical Implications…………………………………………………….64

Limitations and Future Research………………………………………...64

Conclusion……………………………………………………………….66

REFERENCES…………………………………………………………………………..67

APPENDICES

Appendix A………………………………………………………………………………70 Medical History and General Information Form

Appendix B………………………………………………………………………………73 Wash-down Instructions

Appendix C………………………………………………………………………………74 Tgi Pill Instructions

Appendix D………………………………………………………………………………75 Timex Exercise Survey

Appendix E………………………………………………………………………………78 Exercise Testing Data Sheet

Appendix F………………………………………………………………………………81 Twenty Four Hour Urine Tracking Form

Appendix G………………………………………………………………………………82 Nutrition and Fluid Questionnaire

Appendix H………………………………………………………………………………87 Hydration Questionnaire

Appendix I……………………………………………………………………………….89 Dietary Food Record

Chapter 1

REVIEW OF THE LITERATURE

Whole-body imbalances in athletes and non-athletes are detrimental to training and competition. This review will examine how sodium (Na+) and potassium (K+) losses affect physiological changes in the body and an athlete’s ability to sustain elite performance. Further, it will discuss a technique in determining and finding accurate sweat electrolyte concentrations.

Whole-body imbalances have been increasing recognized as detrimental to performance. Gatorade and other electrolyte drink manufacturers promote electrolyte beverages to enhance performance. New sports drinks contain solutions targeted for pre, during and post exercise consumption to replenish fluid and electrolyte losses. Despite the availability of these products, it is still unknown how much fluid and sodium intake is optimal for athletes to prevent performance decrements. Triathletes who hydrate pre, during and post exercise prevent performance detriments and 2-3% body fluid losses post-exercise.1-2 Other athletes over consume fluids during activity, which can lead to hyponatremia.3 Further, athletes excrete sodium in sweat, leading to disruptions in fluid balance. The lack of knowledge and public awareness of hydration can lead to problems as small as performance loss or as serious as death, thus more research and education on hydration are needed.

Sweat and Urine Electrolyte Concentrations

The balance between electrolytes and hydration is extremely important to performance and health of an athlete. Sodium turnover is the movement of sodium from ingestion to excretion, through skin and urine. Nominal values for electrolyte requirements, recommended daily dietary allowance for sodium and potassium are 1100

to 3100 mg/day and 1900 to 5600 mg/day respectivly.4 These values do not accurately depict recommended daily allowance for elite athletes. The American college of Sports

Medicine (ACSM) has published a position stand on exercise and fluid replacement. It states sweat rate average values for different endurance sports, but there is no publication of sweat electrolyte loss average values for different endurance sports, collectively.1

Electrolyte Turnover

Dietary intake has been recorded for Na+ and K+ to evaluate the speed, amount, influences and timing of turnover.4-8 The concentration of sodium that athletes ingest pre-

, during and post- exercise are influential in the movement of sodium throughout the body. Investigating lost electrolytes in sweat can be evaluated by the wash down technique. Wash down evaluation of electrolytes in sweat has been found to be the most accurate testing procedure.9-10 References values seen in cyclists, runners and triathletes for sweat sodium concentration are 14 to 88 mEq/L11 and laboratory testing are 13 to 47 mEq/L12, and 40 to 60 mEq/L13 and sodium urine loss values are 40 to 220 mEq per day.14-15

Consumption of sodium during exercise will change the rate of sweat loss and urine output, and compositions of plasma. A study conducted using eight healthy males physically active on a recreational basis, 22 ± 2 years of age were dehydrated by 2% of body weight by intermittent cycling at 60% VO2max in a 31°C and 73 % relative humidity environment.16 Each subject exercised 10 min: 5 min rest a mean of 51 ± 6 min, the test drink, volume equal to the body mass loss, was taken by each subject 15 mins after exercise for rehydration and 15 mins after rehydration, blood was drawn in time increments of 1, 2, 4, 6 hrs.16 The investigation observed the different effects of

replacement fluids consumed: drink A glucose, B sodium chloride, C potassium chloride and D all four contents. As a result, drinking a glucose based replacement drink for electrolytes and fluids lost had the greatest net negative fluid balance compared to consuming sodium chloride, potassium chloride or all four combined.16 Interestingly, the sodium chloride concentrated drink resulted in the least net negative fluid balance.16-19

Another study looked at different levels of sodium concentrations in fluid when replacement of fluids was warranted. Six subjects recreationally physically active 28 ± 8 yr of age were included in four trials. First each was dehydrated by 1.89 ± 0.17 % of body mass by exercising 5min: rest 5min intervals, 43 minute mean, at 60 % VO2max in 34°C,

60-70% relative humidity on a cycle ergometer.18 Sweat lost was contained in a closed bag structure. In succession of 40 minutes after exercise, replacement fluids were taken over 60 mins, 0, 25, 50, 100 mEq/L of sodium concentration and blood samples were taken 1, 2, 4, 6 hr.18 Results showed a negative sodium balance for 0, 25 mEq/L, a balance for 50 mEq/L and a positive net balance with 100mmol/L.18 (See Figure 1.)

Consequently, the highest sodium content replacement drink resulted in the greatest increase in potassium loss in urine.18

To decrease body mass by 2-3 %, a study conducted with nine male and one female subject, mean of 27.3 yr of age, 50.2 VO2max were asked to exercise on a cycle ergometer at 40% VO2max for total of 90-110 min, increments of 5mins rest and 15 min exercise, in a 36°C, <30 % relative humidity.17 A forearm bag was used to collect sweat and blood samples were taken 30 and 60 min after exercise.17 The second study consisted of six healthy male subjects who regularly participated in recreational activity and none were heat acclimatized. Subjects intermittently cycled on a ergometer at 60 % VO2max in

34°C, 54 % relative hummidity for 10 min exercise and 15 min rest to obtaino 2 % body mass loss.19 Each subjectt had blood drawn and consumed a test drink eithere containing: drink A 108 mosmol·kg,, drink B 158 mosmol·kg, drink c 206 mosmoll·kg, drink D 300 mosmol·kg of sodium.199 These studies are consistent with previous research;r sodium content within fluid replaaceme nt will prevent excess fluid loss and helpp to retain a fluid balance within the humann body. 17-19 Caution needs to be present in regarrds to the amount of sodium content in replacement fluids.

Figure 1. Whole body net soodium balance (□,■) and whole body net cation balaance ( ◊, ) vs. whole body net fluid balance 5 (□,◊) and 6 (■ , ) h after end of volume repletion periood. For net sodium balance, y = 59.75+ 0.28 x; R2 = 0.521. For net cation balance, y = -1.68+0.23x; R2 = 0.577. Points are mean values. Fitted lines aree calculated from 6-h values only. Source; Shirreffs SM, Maugughan RJ. Volume repletion after exercise -induced volume v depletion in humans: replacement of watter and sodium losses. Am J Physiol. 1998;274:F868 -F8875 .

Intake of sodium of different concentrations has been shown to changec the rate of reabsorption of the kidnneys or interstitial fluid space and secretion thhrough urine and sweat.19 A study conduccted with healthy subjects, 4 males and 6 femaales, each subject was recreationally activee and not heat acclimatized. In a two week periiod subjects were

asked to exercise on 5 separate days during 30 minutes of exercise in a 35°C, 40 % relative humidity, each exercise bout of 50, 60, 70, 80, 90 % intensity were randomly selected for each day.20 Each subject had sweat loss and blood taken after testing for electrolyte analysis. Found was that the reabsorption rate of sodium decreased significantly compared to an increase in secretion rate of sodium.20 During the lowest sweat rate, reabsorption rate of sodium was 86 percent and during the highest sweat rate, reabsorption rate was 65 percent.20 Relatively, in another study conducted with 10 healthy college male students, involved in 5 days of preacclimation, 10 days of acclimation and 2 days of recovery. The subjects exercised for 2 hrs on a cycle ergometer

8 at 45 % VO2max in 40°C, 45 % relative humidity, with blood and sweat samples taken.

The results of ten days of 2 hour exercise sessions found a decrease in sweat sodium concentration.8 This is due to the process of enhanced glandular/renal reabsorption to conserve sodium within the body. 8, 13

Potassium is an electrolyte that is primarily sustained within the intercellular space, but losses are still found in sweat and urine.21 Wash down evaluation of sweat reference values of cyclists, runners and triathletes are 2.5 to 4.9 mEq/L11 and laboratory tests are 2 to 5 mEq/L12, 3 to 7 mEq/L9, 4 to 5 mEq/L13 and urine K+ loss reference values are 30 to 90 mEq per day.14-15

The average recommended diets for potassium are 48.6 to 143.2 mEq/day and the following recommendations would not replenish the previous losses.4 A study conducted using eight healthy males physically active on a recreational basis, 22 ± 2 years of age were dehydrated by 2% of body weight by intermittent cycling at 60% VO2max in a 31°C and 73 % relative humidity environment.16 Each subject exercised 10 min: 5 min rest a

mean of 51 ± 6 min, the test drink, volume equal to the body mass loss, was taken by each subject 15 mins after exercise for rehydration and then blood was drawn in time increments of 1, 2, 4, 6 hrs.16 Found was that during exercise in a warm environment, intake of K+ in a fluid replacement decreased the fluid net balance.16

Costill et al. evaluated electrolyte loss from sweat and urine in 10 men and 2 women who were moderately conditioned and heat acclimatized. The experiments were conducted over two 5-day sessions, each subject either replaced body losses with water or an electrolyte drink. Each session subjects cycled in 37-38°C, 55-60 % relative humidity

22 in a heat chamber, at their 50-60 % VO2 max for 1.5-2.5 h of activity. Food and fluid were recorded during the experiment sessions and measured to determine electrolyte content prior to the study. As a result, a high K+ diet 80 mEq/day versus a low K+ diet 25 mEq/day caused no difference in sweat K+ loss.22 During repeated days of heavy intense exercise when consuming 80 mEq/day of K+ the subjects were still able to maintain a positive K+ net balance but with a 25 mEq/day intake of K+ caused a negative net balance.22 The consumption of 80 mEq/day are within the average recommended daily consumption of potassium 48.6 to 143.2 mEq/day.4 Therefore, changes in dietary intake of K+ will increase the conservation of water and maintenance of K+ net balance during long endurance exercise.

Accurate intake of sodium and potassium are valuable in preventing the amount of electrolytes lost in sweat and urine during long endurance exercise. In a warm environment over long endurance or repeated days of exercise, the body will naturally adjust by conservation of those electrolytes.

Plasma Osmolality

Osmolality is the balance between concentrations of electrolytes (e.g. sodium, potassium and chloride) and fluid in the plasma and cells. When replacing fluids with only water during which sodium is lost through sweat, the change in the amount of sodium in blood plasma and whole body is due to osmotic pressure.23 There is a molecular gradient of sodium, potassium, glucose and lipids between the cell and plasma that produces reactions in order to produce muscular function. A decrease in function can occur if there is an imbalance between fluids and electrolytes through homeostasis.

Blood serum concentration reference values by the Massachusetts General

Hospital for adults found 136-145 mEq/L sodium, 3.0-3.5 mEq/L potassium, 98-106 mEq/L chloride.24 These values are common amongst the average population and do not accurately depict the serum concentrations amongst endurance athletes during exercise.

The values can possibly be seen in resting values for those athletes.

To study the effect of heat adaptions on plasma osmolality, researchers examined hypohydrated subjects during a heat stress test.25 Eight male subjects were heat acclimated on a treadmill at 1.34 m·s for two 50 min exercise bouts for nine consecutive days in a 49°C, 20 % relative humidity, after completion of the heat acclimation, four heat stress tests for each subject were completed during euhydrated, 3, 5, 7 % loss of their baseline body weight.25 The results showed a decrease in plasma volume and little to no change in plasma osmolality for moderately 5% hypohydrated subjects. No further decrease in plasma volume occurred, but a large decrease in plasma osmolality occurred in severely 7% hypohydrated subjects.25

Even when comparing two different environments, mild (22±0.2°C, 76±2% relative humidity) and hot environment (31.2±0.2°C, 76.4±1.6% relative humidity) separated by 7 days, 7 male subjects were asked to exercise at self-paced for 40 km cycle followed by a 10 km run on a treadmill for as fast as possible in both trials.26 As a result, no change in plasma volume or osmolality occurred.26

Another study, with ten trained men exercised for one 1 h pretrial and two 3 h experimental trials on a cycle ergometer at 55 % VO2max in 34°C, 65 % relative humidity.27 During different types of ingested fluids, either water or Gatorade containing

6 g/L carbohydrate, 18 mEq/L sodium and 3 mEq/L potassium, resulted in a greater decrease in plasma sodium -2.48 mEq/L ± 2.25 vs. -0.86 ± 1.61 mEq/L with plain water versus a drink containing sodium.27 (Figure 2.) When comparing daily dietary intake, individuals exercising need to consume a well-balanced replacement drink in order to maintain plasma sodium and consume salt in their diet when not exercising.

Contradictory to previous research, a study done with 2 women and 10 men moderately heat acclimatized and moderate-to-well conditioned, cycled 1.5-2.5 h in 37-

38°C, 55-50 % relative humidity, at 50-60 % VO2max, were dehydrated -3 % body weight on two 5 day series.22 One group replenished body water losses with water and the other group replenished fluids with an electrolyte drink, each liter containing (23.0 mEq Na+,

9.3 mEq K+, 14.8 mEq Cl-).22 Groups were reversed for the second 5 day series. Blood samples were taken at rest in the morning and total body wash down was used to collect sweat electrolytes. During the repeated days of heavy exercise and dehydration, plasma volume increased proportional to increases in body Na+ storage.22 As a result, the first day of dehydration will decrease plasma volume proportional to decreases of plasma

osmolality than repeated days of exercise. Plasma volume will increase due to the body conservation of fluids and electrolytes. The body is able to adapt to fluid changes and the environment.

Another study, with five healthy males, experienced to the research procedures, exercised 60-75 % of VO2max for 30 min in 30°C, 40 % relative humidity, within a control, thermal dehydration, and thermal dehydration were infused with a hypertonic saline solution.28 Found, were changes in osmolality during exercise can have negative influences on thermoregulation through elevating thresholds of vasodilation and sweating.28 Similarly, hyperosmolality will decrease the sweat rate response and blood flow modifying thermoregulation response independently of decreased plasma volume.28

With severe hypohydration, sweat rate decreases relative to an increase in core body temperature, but the overall reduction in sweating is due to hyperosmolality rather than hypovolemia.25 The concentration balance between fluid and electrolytes has physiological effects once acclimatized to the environment, suggesting the bodies homeostatic gradient adapts to the environmental changes and corrects the concentrations between plasma volume and cell.

Figure 2. Plasma sodium cooncentration during exercise in the heat in which fluiid replacement was with either water (W) or a ssodium containing sports drink, Gatorade (G). ANOVVA demonstrated a significantly greater decreasese with W (P= 0.0007). Source; Vrijens DMJ, Rehhrer NJ. Sodium-free fluid ingestion decreases plasmma sodium during exercise in the heat. J Appl PPhysiol . 1999;86(6):1847-1851.

Electrolytes and Performmance

Endurance exerciise and competition such as Ironman triathlonns, triathletes are well adaptive to the envivironment of longer races. An importance in knowledgen of fuel and consumption of fluidd warrants further investigation to see if electroolyte content has effects on performance.

Ten trained triaththletes, cycling at maximum oxygen uptake greater than 60 ml/kg/min and have comppleted in one Ironman triathlon previous to the studys in less than

10 hr: 30 min, competed in the 2004 Ironman Western Australia race. Theh race consisted of a 3.8 km swim, 1800 km cycle, and 42.2 km run in 19 -26°C, 44 4 -87 % relative humidity.29 Blood samplees were taken pre (two days before) and post-race.r 29 Triathletes in this current study weere able to maintain sodium/fluid balance. Ass a re sult in the

triathlete population, plasma sodium, potassium and chloride before and after an ironman race found levels were average.29

Similar study, subjects exercising in hot desert weather 17-23.9°C, 46-87 % relative humidity, during the 2000 South African Ironman Triathlon, swam 3.8 km, cycled 180 km, and ran 42.2 km, had blood samples taken pre-race and post-race.30 Those athletes not fueling did not terminate exercise until body loss exceeded 7 percent.30 Fuel such as carbohydrates, protein and lipids are metabolized into ATP which is the main energy source important for performance. Athletes need to fuel during exercise in a warm environment in order to continue to perform and finish the race.

Another study, with ten trained men exercised for one 1 hr pretrial and two 3 hr experimental trials on a cycle ergometer at 55 % VO2max in 34°C, 65 % relative humidity.27 Different types of ingested fluids were consumed every 15 min during exercise to match rate of fluid loss, either water or Gatorade containing 6 g/L carbohydrate, 18 mEq/L sodium and 3 mEq/L potassium, resulted in a greater decrease in plasma sodium -2.48 mEq/L ± 2.25 vs. -0.86 ± 1.61 mEq/L with plain water versus a drink containing sodium.27 Ingestion of only water in the heat caused low sodium plasma concentrations during exercise resulting in a decrease in performance seen through an increase of rate of perceived exertion positively correlated with an increase in exercise time.27 Available sodium in the body are vital to maintain whole-body balance during competition and training.

A comparison study using data from a 2000 ultra-endurance triathlon 224 km race in 17.0-23.9°C, 46-87 % relative humidity with 271 athletes and 2001 ultra-endurance triathlon race in 17.2°C average, 68 % average relative humidity with 469 athletes.30

When evaluating serum, sodium concentrations were higher for those that lost a greater percentage of body weight than those that did not.30 Similarly, when looking at the 2000

African Triathlon, triathletes body loss of 5.2 percent; this increased the mean serum sodium concentration in those athletes post-race.31 The high serum sodium occurred in those largely dehydrated, with a negative correlation between high serum sodium concentrations post-race and performance time.31-32 No correlation was found between sweat rate and rate of change in plasma sodium concentrations.27 An inverse correlation existed, greater rate of plasma sodium change is correlated with a shorter exercise time.27

Low serum sodium concentration affects performance and possibly causing injury or medical emergencies. Consequently, muscle cramping can happen during an ironman triathlon. When comparing two groups 11 cramping and 9 non-cramping finishers were evaluated pre and post during the 2000 South African Ironman Triathlon race, in average temperature of 20.5°C, 68 % relative humidity, a blood sample was taken and surface electromyography post-race. Body composition and percent body weight loss was not different from the control group. Sodium concentrations were lower but within normal clinical range for serum sodium.33

The results of different sodium concentrations are a factor in muscle cramping.

We also know that hyponatremia is a consequence of overdrinking and retention of excess fluid which can happen during exercise, the disruption of the sodium, potassium homeostatic gradient.

Physiology of Hydration

Hydration Effects on Cell Function

Hydration impacts cell function by affecting the cell’s transportation of fluids and electrolytes in and out of the cell. These components affect cellular metabolism by modifying phosphoenolpyruvate carboxykinase expression. 34-36 Hydration affects the genes ability to signal proper reactions within the liver cell. 34-36 The genes responsible for coding for proteins are affected by dehydration, as they are not able to function without equilibrium.34-36

Transcription generates cell signals such as cytokines causing the reaction to occur rapidly with an increased hydration of the cell. Hydration will also change the function of osmoregulatory hormones by disrupting the electrolyte couple-transporters ability to maintain the proper amount of potassium inside the cell and sodium outside the cell.34-36

Fluctuations of ions in and out of the cell are a result of osmotic gradient. When cells are exposed to a hypo-osmotic environment, the cell initially swells and then regain original volume, called regulatory cell volume decrease (RVD).37 The opposite can be seen when the cell is exposed to a hyper-osmotic environment, the cell will initially shrink and then regain original volume, called regulatory cell volume increase (RVI).37

For example, tyrosine phosphorylation is an intercellular signal to activate volume- regulatory response in the intestinal lining.38 Depending on the cell type, mechanisms responsible for RVD and RVI differ, but all involve the activation of ion transport systems in the plasma membrane.37

Osmoregulation or ion-transport effect increased cell volume resulting in a greater cellular proliferation.39 For this process to occur, gene expression needs proper cellular hydration and ambient colloid osmotic pressure.40 Therefore, hydration is

important in maintaining a proper balance within the cell to function through cell signaling and cellular reactions to occur.

Central Regulator System and its Effects on Fluid Shifts

Shifts in fluids throughout the body affect the ability to maintain equilibrium and continuous regular functions during environmental heat or increased stress. Blood is circulated through the body and the central regulator systems in the brain send signals to change the distribution of water throughout the body.

The central regulator system is controlled by the brain. The brain has temperature sensitivity, in regards to selective brain cooling. If the brain is kept cooler, the person can extend the range of body core temperature past the bodies’ functional ability, suggesting that motor cortical drive is regulated by temperature.41 Arterial blood temperature has been proven to be a determinant of brain temperature. This would suggest that the brain is sensitive to the rise in blood temperature.42

Furthermore, long endurance exercise in the heat will affect the blood brain barrier by increasing the permeability and release of a brain specific protein (S-100β) from the central nervous system into the blood.43-44 A rise in serum S-100β, during exercise in the heat, this disruption can be eliminated by drinking water.45 Osmotic equilibrium may be better controlled by decreasing the permeability of the brain structure from dehydration, otherwise preventing mental and physical disruption of the CNS by maintaining whole body fluid balance. Exercising in the heat has resulted in observations of increased cerebral blood flow with a decrease in blood flow to the brain during hyperthermia.46-47 Both factors, exercise and heat stress will affect the metabolic and circulatory pathways in the body.

The circulation of blood through the body during exercise influences water moving out of the intracellular space to maintain extracellular fluid space through the process of sweat.17 When increased sweating occurs, the body must maintain the circulating blood volume to maintain thermoregulation. To attain this necessity the body mobilizes fluid from the intracellular space. Water is also moved from other fluid compartments such as the organs to maintain the cardiac filling pressure and adequate distribution of cardiac output.48, 49 The movement of fluid as a result of increased sweating results in water loss from the interstitial fluid space rather than the intracellular space.17 This reflects between the amount of plasma water loss and the relative exercise intensity.50, 51

The cardiac fluid shift is also due to the extracellular fluid space increasing filtration caused by a rise in pre-capillary hydrostatic pressure in the extremities during exercise as opposed to induced hyperosmolality.52 Most importantly, the regression of water loss is proportional in all fluid compartments during exercise.52 The amount of fluid already in the cardiac system is continuously shifted to maintain blood pressure and proper functioning of the cardiac and thermoregulatory systems. To maintain water balance, the athlete must continue to replenish fluids during exercise in hot or temperate environments.

Sweat Rate

Sweat rate is affected by the blood volume, increase in thermoregulatory, and hormonal response that affect an athlete’s ability to exercise in a hot environment.

Function of sweat is to cool the body and to maintain thermoregulatory balance. Nominal average values of sweat rate as per the American College of Sports Medicine (ACSM)

position stand for an Ironman triathlete is 0.81 L·h-1 on the bike leg and 1.02 L·h-1 on the run leg.1, 53

During an Ironman triathlon event, summer versus winter environmental temperatures will affect different sweat rate responses. In a study performed by Bates et

54 al, subjects cycled for 35 min at 40 % VO2max during a heat stress test in a geographical location where winter conditions average 15-200C and summer conditions 30-350C. It was assumed that the male participants were acclimatized during the summer and un- acclimatized during the winter. As a result, sweat rates in the summer were higher 0.47 ±

0.14 kg·h versus winter 0.41 ± 0.17 kg·h.54

Another heat stress test observed sweat sensitivity pretest hydration and water consumption during exercise in a 90-min at 5% incline treadmill walking at 36 % VO2max

(33 ± 1°C, 56 ± 5 % relative humidity) in ten males who participated regularly in recreational sport activities.55 Four sessions in combination, pretest hydration (two euhydration trials and two hypohydration trials) and during exercise (two water ad libitum trials and two no water trials).55 Each subject completed four consecutive preliminary trials within 20 ± 1 days prior to testing to induce exercise-heat exposure, on a cycle ergometer at 47 ± 2 % VO2max in 33 ± 1°C, 64 ± 8 % relative humidity for 90 min.55 Sweat sensitivity was measured and hypohydrated males with no consumption of water during exercise found to have a greater physiological strain. (Figure 3.) The subjects’ ability to sweat without consumption of fluids resulted in a decrease sensitivity compared to those that were eurohydrated and consuming fluids.55, 56

Figure 3. Sweat sensitivity of each heat stress test normalized for area under heating curve. Values are means ± SE. *Significantly different from all other treatments, P, 0.05–0.01. Source; Armstrong LE, Maresh CM, Gabaree CV, Hoffman JR, Kavouras SA, Kenefick RW, Castellani JW, Ahlquist LE. Thermal and circulatory responses during exercise: effects of hypohydration, dehydration, and water intake. J Appl Physiol. 1997;82(6):2028-2035.

Sweat rate and sensitivity can vary due to external environmental factors, such as heat, wind and humidity. Whether or not the athlete consumes the proper fluids during exercise or prior to exercise, the athlete is in a hypohydrated state. The athlete has to replenish the body relative to the current hydrated state in order for thermoregulatory functions to occur.

Water Turnover

Fluid consumption to replace fluid loss during exercise is dependent on compliance of the athlete either by ad libitum or scheduled drink. A study done with seven male triathletes completed two trials, one in moderate 22 ± 0.2°C, 76 ± 2 % relative humidity and hot 31.2 ± 0.2°C, 76.4 ± 1.4 % relative humidity separated by 7 days.26

Self-paced 40 km cycling then run as fast as possible for a 10 km run was completed by

each subject and water ad libitum was measured.26 To maintain a balance subjects were found to drink more water ad libitum in hotter than cooler environments.26

This is comparable to findings of Maresh et al.57 who studied euhydrated and hypohydrated athletes. Ten healthy males completed four randomized walking trials for

90 min 5 km/h, at 5 % grade at 47 ± 2 % VO2max previous determined prior to testing, in

33 ± 1°C, 64 ± 8 % relative humidty.57 Each subject was allowed to drink ad libitum during the trail and blood samples were taken during exercise. Each trial differed in pretest hydration (euhydration or hypohydration), and water intake during exercise (water ad libitum or no water).57 Athletes dehydrated prior to activity in the heat drink more water ad libitum then subjects who were euhydrated prior to testing. The athletes’ level of hydration was attributed to the athletes’ ability to maintain fluid balance during heat stress and maintenance of the thermoregulatory system during increased sweat rates.

Athletes typically do not consume one hundred percent of their losses.

A study with seven well-trained males examined fluid ingestion on performance during prolonged strenuous exercise in 21.3 ± 0.3°C, relative humidity 43 ± 2 %, cycled for 2 h at 69 ± 1 % VO2 peak receiving during the exercise trail either no fluid or fluid of

100 % or 50 % of the exercise-induced weight loss.58 Right after the 2 h trial the workload was increased to one estimated to elicit 90 % VO2 peak and subjects rode to exhaustion.58 When athletes performed cycling to exhaustion, those who replenished one hundred percent of fluid losses had higher sweat rates than 50 percent replacement or no fluid replacement groups.58 The athlete’s ability to maintain fluid balance increases the athletes thermoregulatory function and sweat rate.

If athletes are unable to maintain a balance between fluid loss and fluid replacement, blood volume will decrease. Weight loss as a result of sweat loss was positively correlated to changes in plasma volume in athletes competing in a triathlon race.59 Hundred and eighty-one male triathletes participated in the study during a ultra- distance triathlon (swim 3.8km, bike 180km and run 42.2km) an average 20.5°C, average

68 % relative humidity, conclusively the overall intensity of the race was not indicative of loss of body weight, due to the overall maintenance of human body fluid balance.59 The athletes drank enough fluids during the race to have a positive balance.

Intake of sodium in different concentrations will affect the net water balance post exercise. (Figure 4.) Six subjects recreationally physically active 28 ± 8 yr. of age were included in four trials. First each was dehydrated by 1.89 ± 0.17 % of body mass by exercising 5min: rest 5min intervals, 43 minute mean, at 60 % VO2max in 34°C, 60-70% relative humidity on a cycle ergometer.18 Sweat lost was contained in the closed in bag structure. In succession of 40 minutes after exercise, replacement fluids were taken over

60 mins, 0, 25, 50, 100 mEq/L of sodium concentration and blood samples were taken 1,

2, 4, 6 hr.18 The highest concentrated drink of 100 mmol/l of sodium sustained a greater net fluid balance compared to the other drinks. 18This study suggests the influence of sodium replacement occurring post exercise will have a positive effect on the conservation of water within the human body.

Figure 4. Whole body net fluid balance calculated from estimated sweat losss, volume of fluid ingested, and urine output oover course of experiment. Pre -exercise urine samplee is not included in these calculations. Points aree mean values. Source; Shirreffs SM, Maugugha n RJ. Volume repletion after exercise-induced volume v depletion in humans: replacement of watter and sodium losses. Am J Physiol. 1998;274:F868 -F8875. Overall, neet fluid balance can be controlled by consumptio on of electrolytes and fluid by the athlete.

Core Temperature and Hydration

The production of sweat helps to maintain core body temmperature during thermoregulation. This ccan be evaluated through looking at sweat ratees and skin blood flow relative to core tempperature.

Current evaluationn of sweat rat es compared to core temperature, a study had nine heat acclimatized subjectts each completed nine 50 min consent sessions on a treadmill in

30°C, 50 % relative hummidity. 56 Each subject exercised at either 25, 45 oro 65 % intensity

when euhydrated and when hypohydrated at 3 and 5 % of their baseline body weight.56

Found were sweat rates correlate with increases in core temperature, blood flow will be redistributed to the skin during an increase in core temperature during dehydrated conditions.56 In addition to an increase in core temperature, when environmental temperature increases, so do sweat rates.55 Some athletes’ sweat loss is not being replenished with one hundred percent of fluid lost, and the amount ingested is predictive of environmental factors.57 Those competing in a hot environment or high intensity performance will produce more sweat to keep the body cool during heat stress.56

Furthermore, hypohydrated subjects who do not consume water during 90mins of exercise in a warm environment showed an increase in rectal temperature after the first

10 minutes.55 (Figure 5.) Interestingly, the average core temperature decreased from day one to four (39.3 ± 0.2 C to 38.9 ± 0.4 C). Possibly partial acclimatization may have occurred.55 As previously stated, hypohydrated subjects had a decrease sweat sensitivity, with overall greater core temperature, therefore an assumption can be made that the body conserves fluids during a dehydrated state to focus on preventing core temperature rising in a warm environment.

Figure 5. Rectal temperature (Tre) responses during the four 90-min heat stress tests: euhydration + ad libitum water (EW + W), euhydration + no water (EU + NW), hypohydration + ad libitum water (HY + W), and hypohydration + no water (HY + NW). Values are means ± SE; n=10. bpm, Beats/min. *P < 0.05–0.0001 from all other treatments at same time point. Source; Armstrong LE, Maresh CM, Gabaree CV, Hoffman JR, Kavouras SA, Kenefick RW, Castellani JW, Ahlquist LE. Thermal and circulatory responses during exercise: effects of hypohydration, dehydration, and water intake. J Appl Physiol. 1997;82(6):2028-2035.

Ten trained triathletes, cycling maximum oxygen uptake greater than 60 ml/kg/min and have completed in one Ironman triathlon previous to the study in less than

10 hr: 30 min, competed in the 2004 Ironman Western Australia race, 3.8 km swim, 180 km cycle, and 42.2 km run in 19-26°C, 44-87 % relative humidity.29 The study found that the faster swimmers after the swim leg had higher core temperatures.29 The subjects lost

2.3kg (-3.0%) body mass during the Ironman race and core temperature increased by an average of 1C over the course of the race, average 38.1C.29 Core temperature did not increase significantly despite performing at high level of intensity, 86% of maximal heart

rate.29 Well trained triathletes are able to compete in warm conditions without thermoregulatory failure.

Eleven members of the Australian National Road cycling Squad were studied after 6 weeks of pre-season training. Cycling in 32C (HT) and 23C (NT), 60 % relative humidity, during two 30-min time trials, rectal temperature increased at the same rate.41 During self-paced exercise in the heat, this study demonstrated that core temperature can be utilized to select relative power output. Interesting observation, when subjects exercised in the heat while drinking various fluids, subjects still fatigued at the same core temperature.41 It is still unknown if an athlete will fatigue at a critical core temperature during different stats of hydration.

Fluid replacement in a study done with eight male cyclists exercising for 50min during which they consumed a large fluid replacement (1330 ± 60 ml) of a 6% carbohydrate (79 ± 4g) and a small fluid replacement (200 ± 10 ml) of a 40% maltoedextrin (79 ± 4 g) solution of water while in the warm environment (31.2 ± 0.1C,

54 ± 3% relative humidity).60 Found that rectal temperature and esophageal temperature was significantly (p<0.05) higher at the 40min to 50min of exercise and after performance in small fluid replacement than during large fluid replacement.60

Hydration, fluid replacement, power output, and environmental adaptions during exercise are important in preventing the body in reaching critical core temperature.

Hydration changes during Exercise and Heat Stress

Exercising in a hot environment causes the human body to adapt by changing heart rate, cardiac output, and thermoregulatory system activation. Changes in fluid volume in the cardiac and thermoregulatory system causes increased movement of fluid

when overloaded due to an increase in heat production in the human body. Heart rate increases to maintain blood pressure which falls during exercise due to the changes in osmotic pressure gradient. Increased heart rate reflects strain on the cardio vascular system. Blood flow is directed by dilation or constriction of blood vessels that lead to various vascular beds in the body.

Dehydration occurs more quickly in hot environments due to higher demands of body fluid to maintain core temperature due to increased sweat rates. For every 1% of body mass loss, heart rate increases by 5-8 beats per minute. The change is accompanied by decreased cardiac output and increased core body temperature by 0.2-0.30C. 61-67

Therefore, dehydration causes the heart to work harder to maintain the same effective cardiac output while exercising in the heat.

Differences in rates of dehydration in warmer climates, such as those found in the southern states versus warmer seasons in the north, have a large effect on the body’s ability to adapt. Heat adaptions occur as a result of heat stress to maintain equilibrium and performance. Dehydration of just 4% has been shown to decrease blood volume by

200 ml, which has an effect on stroke volume.68 Under hyperthermia-induced conditions, this decreased blood pressure and cardiac output, make the dehydrated athlete less able to cope with hyperthermia. 68-70

Hydration and Performance

The level of hydration during physical activity affects sport performance. Whether one hundred percent, fifty percent or no fluids are replaced, there are effects on sweat rate, cardiac output, plasma electrolytes and overall performance. A study with seven well-trained males examined fluid ingestion on performance during prolonged strenuous

exercise in 21.3 ± 0.3°C, relative humidity 43 ± 2 %, cycled for 2 h at 69 ± 1 % VO2 peak receiving during the exercise trail either no fluid or fluid of 100 % or 50 % of the exercise-induced weight loss.58 Right after the 2 h trial the workload was increased to one

58 estimated to elicit 90 % VO2 peak and subjects rode to exhaustion. One hundred percent fluid replacement can increase time to exhaustion by fifty percent compared to those who do not replace fluid losses during exercise.58

The study completed by Below et al.60 with eight men who completed an acclimation protocol consisting of four 1 h bouts over 10 days, cycling in 31.2 ± 0.1°C,

54 ± 3 % relative humidity, prior to testing.60 During testing each performed for fifty minutes at eighty percent VO2max completed on a cycle ergometer maintaining a lactate threshold above 5% in 31.2 ± 0.1°C, 54 ± 3 % relative humidity.60 Each subject consumed various fluids during the trails ingested immediately before exercise (40% of the total volume), at 15 min (20%), at 25 min (20%), and at 34 min (20%). During exercise subjects randomly received either fluid with 6% carbohydrate, fluid, carbohydrate or placebo. The volume of fluid consumed in the fluid/carbohydrate and fluid averaged 1330 ± 60 ml to replenish fluids lost during the exercise and maintain body weight. The athletes who had large fluid replacement compared with those who had a small fluid replacement were thirty seconds faster.60 The athletes were able to generate thirty watts more than those who had a small amount of fluid replacement.33 The athlete who is already dehydrated and suffering from exhaustion increases their deficit in performance output.33

Performance output studied in thirteen well trained healthy women, all participated previously in long distance races, menstrual cycle and urinary output was not

recorded. Each completed three, four-hour runs on an out-door track, trial one average

5.3°C, trial two 19.4°C and trial three 13.9°C.71 Food intake 24 hours prior to the first trail was recorded. During the test trail each consumed three different fluids, one drink with low sodium, one drink with high sodium and water. It was found that there was no change in sodium plasma concentrations. Higher plasma sodium drink consumption after the run and smaller decreases in plasma sodium during the trials had no effect on better performance over four hours of exercise.71

Furthermore, a study done by Sharwood et al. found that significantly dehydrated triathletes had no performance decrements during an ultra-endurance race.30 Subjects exercising in hot desert weather 17-23.9°C, 46-87 % relative humidity, during the 2000

South African Ironman Triathlon, swam 3.8 km, cycled 180 km, and ran 42.2 km, had blood samples taken pre-race and post-race.30 Contradictory to previous literature, body mass loss above seven percent did not prove to be a related to either higher body temperatures or impaired performance.30 There may not be a need to increase fluid intake in triathletes competing in a mild environment 20.50C (17-23.90C) to prevent heat illness.

During the 2000 African Triathlon, one medical case was found where an athlete had gained 3kg of body weight.32 An excess of fluid replacement can result in detrimental effects on performance.27,31,3 Comparable to another study done at the same race, athletes lost a significant amount of weight, a mean of 3.7kg (5.2 percent), and continued to show less mean weight then pre-race measurements at the prize ceremony the next day, a loss of 1.3kg (3 percent).30,31 Sweat rates that equaled ingestions rates did affect cycling performance during the race. Surprisingly enough, higher levels of dehydration did not affect run performance or finish times. Athletes with the highest levels of weight loss had

the fastest run times.31, 72, 73 Overall athletes still need to be conscious of fluid ingestion indicative to sweat rates to maintain proper performance. Athletes well hydrated competing in shorter anaerobic exercise type conditions in a warm environment perform better than those who are not well hydrated.

Athletes who are hydrated can prevent performance decrements and improve overall performance. A body mass loss of 5.2 % has been shown to decrease race time during ultra-endurance competition.31 Athletes need to be aware that individual hydration is important and may be more beneficial than the consequence of a large percentage of body mass loss.

Urine Excretion

Urine excretion common values for daily urine losses for men are 690 to 2690 mL/day and women 490 to 2260 mL/day.20,27 These values are a collection of reference values for the average person, a triathlete may excrete more or less.

One study using 181 male triathletes competing in an Ironman triathlon, Current research on urine electrolyte loss found that, during an Ironman triathlon, sodium concentrations were maintained with 5 percent body weight loss from registration to finishing the race.59 The research does not take into account that triathletes will eliminate or void their bladder many times before the start of the race, therefore the athlete looks like they have lost a large amount of weight. During this study plasma volume was inversely correlated with changes in serum sodium.59

Voidance of fluids can be modified due to changes in diet. Drinking water or an electrolyte free glucose solution increases urine output, opposed to drinking a high concentration sodium drink which results in a decrease in urine output.16, 17

Another study ddone by Costill et al. evaluated differences between a high potassium diet (80 meq K+ a day) and low potassium diet (25 meq K+ a day).22 Urine output was significantly rreduced in the high K+ diet as opposed to the loww potassium diet.

Sodium urine excretion dduring this study was also significantly less in booth modifications of a high and low potassiium diet .22 These observations can suggest that diet intake of K + can influence renal waterr and sodium excretion and conservation duringg repeated days of heavy exercise.77 (Figure 6.)

Figure 6. Urine output over ttime. Pre -exercise sample has not been shown. Points area median values. Source; Shirreffs SM, Maughhan RJ. Volume repletion after exercise -induced volumme depletion in humans: replacement of watter and sodium losses. Am J Physiol. 1998;274: F868-F8875.

Finally a study ddone with ten trained endurance subjects conduucted a maximal exercise test to determinee VO 2max, and then cycled during one pretrial forr 1 h and two test trails for 3 h, all tests at 55 % VO2max in 34°C, 65 % relative humidity whiling drinking either water or a sodium containing drink. Found urinating less or at a loower rate of urine

production is correlated with a greater rate of plasma sodium change.27 Therefore, when ingesting sodium, raising the concentration within the blood will result in a lower urine production.

Similar to the previous study by Costill et al., a high potassium diet will result in a low urine output. Overall increased intake in electrolyte content will change the rate of urine production.

Summary and Purpose of Study

An abundance of literature on the importance of hydration and sodium replacement to maintain equilibrium during activity can be referenced. Both hydration/carbohydrate protocols suggested by the National Athletic Trainers Association

(NATA) and ACSM have a major importance in overall performance to be able to maintain intensity and decrease finish time. The physiological stress and the decrease in whole-body imbalances in a hot environment can negatively affect an athlete by increasing chance of injury and dehydration decrements.

Overall the research demonstrates, through preventative actions, consuming the proper volume of fluids and replacing the right amount of sweat electrolyte loss, renal

Na+ and K+ conservation decreases the chance of electrolyte deficiencies and dehydration.22

To further evaluate the importance of hydration and re-fuel, evaluations of athletes in a heated environment are needed in order to control variables to determine proper body loss and consumption. An interesting factor was to find differences between female and male athlete sodium and fluid balance. This could adjust current trends in hydration protocols, helping to create a very specific protocol, adapted to individuals.

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54. Bates GP, Miller VS. Sweat rate and sodium loss during work in the heat. J Occup Med Toxicol. 2008;3(4):1-6. 55. Armstrong LE, Maresh CM, Gabaree CV, Hoffman JR, Kavouras SA, Kenefick RW, Castellani JW, Ahlquist LE. Thermal and circulatory responses during exercise: effects of hypohydration, dehydration, and water intake. J Appl Physiol. 1997;82(6):2028-2035.

56. Montain SJ, Latzka WA, Sawka MN. Control of thermoregulatory sweating is altered by hydration level and exercise intensity. J Appl Physiol. 1995;79(5):1434-1439.

57. Maresh CM, Gabaree-Boulant CL, Armstrong LE, Judelson DA, Hoffman JR, Castellani JW, Kenefick RW, Bergeron MF, Casa DJ. Effect of hydration status on thirst, drinking, and related hormonal responses during low-intensity exercise in the heat. J Appl Physiol. 2004;97:39-44.

58. McConell GK, Burge CM, Skinner SL, Hargreaves M. Influence of ingested fluid volume on physiological responses during prolong exercise. Acta Physiol Scand. 1997;160:149-156.

59. Hew-Butler T, Collins M, Bosch A, Sharwood K, Wilson G, Armstrong M, Jennings C, Swart J, Noakes T. Maintenance of plasma volume and serum sodium concentration despite body weight loss in ironman triathletes. Clin J Sport Med. 2007;17:116-122.

60. Below PR, Mora-Rodriguez R, Gonzalez-Alonso J, Coyle EF. Fluid and carbohydrate ingestion independently improve performance during 1 h of intense exercise. Med Sci Sports Exerc. 1995;27(2):200-210.

61. Adolph EF, Brown AH, Goddard DR, Gosselin RE, Kelly JJ, Molnar JW, Rahn H, Rothstein A, Towbin EJ, Wills JH, Wolf AV. Physiology of man in the desert. NY Interscience. 1947; 16-342.

62. Sawka M, Coyle E. Influence of body water and blood volume on thermoregulation and exercise performance in the heat. Exerc Sport Sci. 1999;27:167-218.

63. Coyle EF, Montain SJ. Benefits of fluid replacement with carbohydrate during exercise. Med Sci Sport Exerc. 1992a;24:S324-S330.

64. Colye EF, Montain SJ. Carbohydrate and fluid ingestion during exercise: are there trade-offs?. Med Sci Sport Exerc. 1992b;24:671-678.

65. Cheuvront SSM. Physical exercise and exhaustion from heat strain. J Korean Soc Living Environ Sys. 2001;8:134-145.

66. Cheuvont S, Haymes E. Thermoregulation and marathon running: biological and environmental influences. Sports Med. 2001;2:202-208.

67. Sawka MN, Montain SJ, Latzka WA. Hydration effects on thermoregulation and performance in the heat. Comp Biochem Physiol Mol Integr Physiol. 2001;128:679-690.

68. Gonzalez-Alonso J, Morda-Rodriguez R, Below PR, Coyle EF. Dehydration markedly impairs cardiovascular function in hyperthermic endurance athletes during exercise. J Appl Physiol. 1997;82(4):1229-1236.

69. Nadel ER, Fortney SM, Wenger CB. Effect of hydration state on circulatory and thermal regulations. J Appl Physiol Respir Environ Exerc Physiol. 1980;49(4):715-721.

70. Mountain SJ, Coyle EF. Fluid ingestion during exercise increases skin blood flow independent of increases in blood volume. J Appl Physiol. 1992;73(3):903-910.

71. Twerenbold R, Knechtle B, Kakebeeke TH, Eser P, Muller G, von Arx P, Knecht H. Effects of different sodium concentrations in replacement fluids during prolonged exercise in women. Br J Sports Med. 2003;37:300-303.

72. McConell GK, Stephens TJ, Canny BJ. Fluid ingestion does not influence intense 1-hour exercise performance in a mild environment. Med Sci Sports Exerc. 1999;31:386-392.

73. Noakes TD, Sharwood K, Collins M, Perkins DR. The dipsomania of great distance: water intoxication in an ironman triathlete. Br J Sports Med. 2004;38(16)1-5.

Chapter 2

Introduction

Recommendations for consumption of sodium replacement during and after long endurance exercise and competition have recently been questioned. Duration, intensity and the environment of triathlons can influence sweat and sodium loss with outstanding detrimental effects.

An Ironman is a grueling event that involves a 3.8km swim, 180km bike and

42km run.1 As a result; most athletes will complete the race between 10-13 hours. The fastest race time ever recorded was by male Andreas Raelert for all Iron-distance races at

7:41:33 and female Chrissie Wellington at 8:18:13.2 Another event is the half Ironman which involves a 2km swim, 90km bike and 21km run.1 Most will complete the race between 5-6 hours. Both triathlon events consist of very hot humid temperatures like the extremes seen in Hawaii, which can reach higher than 100 F on the pavement.1

Environmental variability of hot or cool and dry or humid temperatures can be seen during long endurance racing.

Exercising in warmer conditions greatly increases the demands of thermoregulation.3-5 As a result, increases in the depletion of the most common components; sodium, potassium and chloride are lost in sweat. Electrolytes lost in the sweat need to be replenished after very intense work outs. Essentially the capillaries that reabsorb the electrolytes cannot do so when the flow of sweat increases, when sweat rate increases, so do electrolyte loss. During long exercise, when electrolytes are lost through sweat it is important for the athlete to maintain equilibrium. Maintenance of equilibrium

occurs with certain physiological changes such as distribution of water and electrolytes within the body, osmotic pressure gradient changes and thermoregulation.6

To maintain an electrolyte and fluid balance within the body, we must intake the same amount of electrolyte and fluid that is being lost in sweat during exercise, respiratory and urine and fecal matter.7 In order to do this, we need to maintain a healthy diet and consistently ingest food with high nutrient value. Nutrition is only one component of success in competing and training as an endurance athlete.

Dietary intake has been recorded for Na+, K+, and Cl- to evaluate the speed, amount, influences and timing of turnover.7-11 The concentration of sodium that athletes ingest pre, during and post exercise are influential in the movement of sodium throughout the body. Intake of fluids containing an electrolyte has been found to decrease the amount of electrolyte lost in sweat and urine.12 Interestingly, sodium chloride concentrated drinks when consumed after exercise results in the least net negative fluid balance.12-15 The amount found to be optimal in replenishing sodium lost in sweat is 50mmol/L. As a result sodium content within fluid replacement will prevent excess fluid loss and help to retain a fluid balance within the human body.13-15

Sodium turnover is an important component to evaluate in determining ones needs when training and competing as an endurance athlete. The aim of this study was to investigate the effects of sodium turnover between male and females through sweat loss, 24 hour urine loss and 24 hour diet record of endurance exercise in a warm environment.

Chapter 3

Scientific Research Methods

Subject Characteristics

The 20 males and 15 females whom participated in the study were elite Timex sponsored triathletes. Thirty-two subjects had completed half Ironman triathlons (men 18

± 15, women 9 ± 8) and 31 subjects completed Ironman triathlons (men 12 ± 18, women

7 ± 8). The subject characteristics are as follows (mean ± SD): age (36 ± 10 y), weight

(68.9 ± 10.2 kg), and height (177 ± 8 cm) (see Table 4.1).

Exclusionary criteria were as follows: 1) no chronic health problems, 2) no history of exertional heat stroke within the past 3 years that deemed exercise unsafe according to an expert in the field, 3) no history of cardiovascular, metabolic or respiratory disease, 4) no history of suspected obstructive disease of the gastrointestinal tract (including but not limited to diverticulitis and inflammatory bowel disease), and 5) no current musculoskeletal injury that limits physical activity.

Subjects were recruited from a meeting held at the Timex Performance Center, in

East Rutherford, NJ in February 2012. The researchers conducted the recruitment sessions as an informative session that described the study. The meeting attendees had no obligation to participate in this study and participated on their own free-will. Each subject was advised on the adherent risks and experimental procedures verbally and in writing.

All subjects gave their informed, written consent and the experiment was approved by the

University of Connecticut Institutional Review Board.

Table 4.1.Subject demographics from observational period Male (n = 20) Female (n = 16) Characteristics Mean SD Mean SD Age (yr) 38 12 33 6 Height (cm) 181 6 171 6 Weight (kg) 76.1 7.0 60.1 5.4 Body Fat (%) 11.1 4.1* 17.2 4.4 Fastest Half Ironman (min) 258 24 282 19 (hour:min) 4.30 0.40 5.09 0.32 Fastest Ironman (min) 590 61 615 41 (hour:min) 10.23 1.02 10.25 41.1 Total Half Ironman Races 18 15 9 8 Total Ironman Races 12 18 7 8 * Significantly different from females, p<0.05.

Preliminary Procedures

Subjects completed a medical history questionnaire, exercise training survey, and nutritional questionnaire prior to completing the exercise testing session. The day before or morning of testing, each subject ingested a thermistor (HQ Inc, Palmetto, FL) to measure gastrointestinal temperature (Tgi). This took place 6-12 hours prior to testing to

16 adequately place the thermistor in the small intestine. If the Tgi pill was passed prior to the exercise bout the subjects were given the choice of using a second pill as a suppository or inserting a rectal thermistor, YSI Temperature Sensor (4600 Precision

Thermometer and 401 General purpose probe, Advanced Industrial Systems Inc., Yellow

Springs, OH) 10cm beyond the anal sphincter.

Prior to testing, each subject provided a urine sample to assess urine color using

The Urine Color ChartTM (Human Hydration, LLC, Hampton, VA) and urine specific gravity with a handheld refractometer (Refractometer A300 Clinical, Atago, Tokyo,

Japan). Nude body weight was assessed using a scale (BWB-800S, Tanita, Arlington

Heights, IL) after subjects voided their bladder.17 Percent body fat was measured by a

trained physiologist via hand held Lange skinfold calipers (Beta Technology, Santa Cruz,

CA). Skinfolds were assessed at the chest, abdomen and thigh for men, and triceps, suprailiac and thigh for women, three times to obtain an average calculation. Percent body fat was calculated using the 3-site skinfold equation for men and women, respectively;

Body Density = 1.10938 - (0.0008267 x sum of chest, abdomen and thigh skinfolds in mm ) + (0.0000016 x square of the sum of chest, abdomen and thigh) - (0.0002574 x age).18

Body Density = 1.0994921 - (0.0009929 x sum of triceps, thigh and suprailiac skinfolds)

+ (0.0000023 x square of the sum of triceps, thigh and suprailiac skinfolds) - (0.0001392 x age in years).19

Once body density was found, the Siri Equation was used to find percent body fat;

% Body Fat = (495 / Body Density) – 450.20

Resting heart rate was obtained while the subjects lied supine on the floor for 5 minutes. The lowest resting heart rate was used for analysis. Each subject was fitted with a heart rate telemetry strap (Timex® Flex TechTM Heart Rate Monitor Strap, Timex Heart

Rate Monitor digital collection) and a Timex Ironman Triathlon watch (Timex Ironman

Race TrainerTM Digital Heart Rate System 5K216, Timex Group USA, Inc., Middlebury,

CT). Subjects voided their bladders in a urine collection jug for 24 hours which, began prior to the experimental procedures.

Experimental Procedures

Subjects exercised either on a treadmill (Woodway USA Inc., Waukesha, WI) or a friction resisted cycle ergometer (Cycleops 400 Pro Indoor Cycle, Cycleops, Madison,

WI) using a cycling computer with PowerTap Technology (Joule 3.0, Saris Cycling

Group, Madison, WI). Subjects were asked to exercise at race pace for a half Ironman in a heated environment ((28.0ºC ± 0.5, 27.2 % ± 4.9 relative humidity (RH)) for 45 minutes

(see Table 4.2). Three fans were used to provide comfort to the subjects. Subjects consumed water ad libitum throughout the exercise session. Subjects were provided a towel and encouraged to blot excess sweat away from the body during the run or cycle.

Heart rate and core body temperature was measured every five minutes during exercise for athlete safety. Subjects’ perceived exertion was assessed via the Rate of Perceived

Exertion chart.21

Objective stopping criteria was established: 1) core temperature greater than 40ºC,

2) heart rate ten beats within predicted maximum heart rate (220-age), 3) subject request,

4) unsteady gait, or 5) completion of the 45 minute exercise bout.

Table 4.2.Exercise data during 45min of exercise Measures Mean SD Ambient Temperature (°C) 28.1 0.5 Ambient Relative Humidity (%) 27.7 4.6 Sweat loss (L) 1.19 0.37 Sweat rate (L/hr) 1.64 0.46 Percent Dehydrated (%) 1.18 0.62 Fluid consumed (L) 0.37 0.33 Exercise time (min) 43.4 3.8 End exercise Tgi (°C) 38.96 0.52 End exercise heart rate (bpm) 167 12

Post Exercise Procedures

Nude body weight was measured after subjects wiped off all excess sweat into a towel which was used to analyze sweat electrolyte levels. A urine sample was taken and measured for urine specific gravity and urine color. The subjects redressed in their workout clothes to prepare for the whole body wash down.

The towels used to collect sweat during the exercise bout and dry off before the body weight measurement, hair accessories and heart rate monitor straps were placed in a

19-inch round wash down tub. The tub was fitted with a large plastic sheet to collect wash down rinse water. The participant was washed using 2 gallons of de-ionized water, and scrubbed their entire body to wash off as many electrolytes as possible.22-23 Water was poured over the subjects’ garments and asked to scrub under their clothing. Once finished, the participant removed their clothing, which may have contained remaining electrolytes, and was placed back into the wash tub to be rinsed with the wash down water to equilibrate the electrolyte concentrations of the water and clothing.

Prior to testing, subjects’ exercise clothing was washed through one full automated wash cycle, using plain water without soap or detergent to ensure no electrolytes were present before the exercise session. Subjects rinsed their entire body

(including hair) the morning of testing without soap, and did not wear makeup, perfumes, or deodorant. Hair was dried before testing to ensure accuracy of sweat rate concentrations.

Sodium Turnover Analysis

Urine was collected from all subjects for 24 hours to assess sodium turnover. Two samples of urine and wash down rinse water were analyzed for sodium, potassium, and chloride with an electrolyte analyzer (Easy Electrolytes, 6601-D, Medica, Bedford, MA).

Averages of the samples were used for analysis. The electrolyte analyzer performed an internal calibration prior to measures taken (Reagent Module, Easy Electrolytes, Medica,

Bedford, MA).

Twenty four hour diet was imputed into a nutritional evaluation program (The

Food Processor and Fitness software, ESHA Research, Inc., Salem, OR) to calculate the nutritional compositions of foods and fluids consumed. Each subject met with our nutritionists on the last day of the study to thoroughly evaluate each diet recorded for clarification. The USDA food database (National Nutrient Database for Standard

Reference, Nutrient Data Laboratory, Agricultural Research Service, Beltsville, MD) was used to fill missing content in certain foods.

Intensity Analysis

Subjects’ exercise intensity for the run test were split by ‘Fast Men’(n = 7), ‘Slow

Men’(n = 7), ‘Fast Women’(n = 7) and ‘Slow Women’(n = 6) to determine differences in sweat content. Intensity was calculated as min/mile. To create equal groups ‘Fast Men’ were determined to have a pace time > 7:00 min/mile and ‘Slow Men’ were determined to have a pace time < 7:00 min/mile. ‘Fast Women’ were determined to have a pace time

> 8:00 min/mile and ‘Slow Women’ were determined to have a pace time < 8:00 min/mile.

Statistical Analysis

All results are represented as means (SD). Data was analysed using the SPSS software (SPSS, IBM Corporation, Armonk, NY). Significance was set at p<0.05, 95% level of confidence. Comparisons were made by running an independent sample t-test, comparing experimental data between males and females and top finishers versus bottom finishers (n = 35). One-way multivariate analysis of variance for unrelated measures between (Gender) within (run exercise intensity, electrolyte loss) factors mixed model

MANOVA.

Chapter 4

Results

The subject’s stated fastest half Ironman time as 257.8 to 281.6 min and fastest

Ironman time as 590.3 to 614.7 min for male and female respectively. Ambient conditions during the event were 28.1 ± 0.5 C and 27.7 ± 4.6 % RH. Exercise data means were as follows; sweat loss 1.190 ± 0.37 L, sweat rate 1.642 ± 0.46 L·hr2, dehydration 1.18 ± 0.62 %, fluid consumed 0.367 ± 0.33 L, exercise time 43.4 ± 3.8 min, end exercise core temperature 38.96 ± 0.52 C, and end exercise heart rate 167 ± 12 bpm.

Differences were found with finish time with speed p=0.017, body fat % p=0.001, total half-Ironman p=0.037. Sample size for the different groups were top finishers 10 males with no females and bottom finishers 5 male and 5 female. Top finishers sample size was concentrated by males only. (See Table 5.1)

Table 5.1. Finish time versus speed, body fat (%), and exercise speed Top 10 Bottom 10 Variables Mean SD Mean SD Speed (min/mile) 8.45 0.91* 6.98 0.42 Body Fat (%) 9.19 2.85* 17.33 2.92 Total Half Ironman Races 24 19* 8 5 *Speed, body fat (%) and total half-Iroman was significantly different from females.

No differences were found comparing variables to different exercise types and no differences were found when comparing top and bottom finishers with respect to electrolyte loss (see Table 5.2).

Table 5.2. Comparison oof ten fastest versus ten slowest half -ironmann finishers Top 10 Bottom 100 Measures Mean SD Mean SDS Sweat loss (L) 1.24 0.44 1.14 0.340 Sweat (L·hr1) 1.72 0.54 1.60 0.400 Dehydration (%) 1.16 0.69 1.02 0.670 Drink consumed (L) 0.36 0.26 0.47 0.480 Drink consumed (L·hr1) 0.53 0.42 0.64 0.610 Data are mean (SD).

Sweat Measures

After investigatingg electrolyte losses and fluid shifts during exerccise , in Table 5.3, electrolyte variability betwween male and female was found in sweat loss (See( Figure 6.1).

Figure 6.11. Sweat and fluid consumption during exerciise *Significantltly different from females, p=0.001.

Table 5.3. Sweat rate/loss, dehydration and consumption of fluids during 45min testing Male Female Measures Mean SD Mean SD Sweat loss (L) 1.39 0.31* 0.95 0.27 Sweat Rate (L·hr1) 1.88 0.38* 1.34 0.36 Relative Sweat Rate (ml·kg· hr1) 25.97 9.29 21.20 6.53 Percent Dehydration (%) 1.29 0.70 1.05 0.48 Drink consumed (L) 0.40 0.41 0.32 0.17 Drink consumed (L·hr1) 0.56 0.56 0.44 0.21 *Significantly different from females, p=0.001.

Men had greater (p=0.004) sweat sodium loss (60.3 ± 19.9 mEq) and a greater

(p=0.01) rate of sweat sodium loss (82.4 ± 26.6 mEq·hr) than women (39.4 ± 19.9 mEq;

56.5 ± 30.1 mEq·hr), respectively. Sweat potassium mass loss was less in women than men (5.6 ± 0.9 mEq vs 7.5 ± 1.7 mEq, respectively, p=0.001) and rate of sweat potassium loss was higher in men than women (10.2 ± 2.1 mEq·hr vs 8.0 ± 1.5 mEq·hr, respectively, p=0.001). Sweat sodium and potassium concentrations had no significant difference between sexes. Laboratory electrolyte variables can be seen in Table 5.4.

Table 5.4. Sweat electrolytes during laboratory testing Male Female Combination Measures Mean SD Mean SD Mean SD Sweat [Na+] (mEq/L) 44.8 14.8 44.1 23.2 44.5 18.7 Sweat Na+ (mEq) 60.3 19.9 * 39.4 19.9 51.0 22.2 Sweat Na+ (mEq/hr) 82.4 26.6 * 56.5 30.1 74.4 6.1 Sweat [K+] (mEq/L) 5.5 1.0 6.4 2.2 5.9 1.7 Sweat K+ (mEq) 7.5 1.7* 5.6 0.9 6.7 1.7 Sweat K+ (mEq/hr) 10.2 2.1 * 8.0 1.5 9.4 0.4 * Significantly different from female.

80 70 Men 60 Women 50 40 30 *

Measure (mEq/L) Measure 20 10 0 Sodium Sodium Potassium mEq/L·kg

Figure 6.2. Sweat electrolytes during laboratory testing *Significantly different from female, p=0.001.

90 * 80 70 * Men 60 Women 50 40 30 20 * * 10 0 Sodium mEq Sodium Potassium Potassium mEq/hr mEq mEq/hr

Figure 6.3. Sweat electrolytes during laboratory testing *Significantly different from female, p<0.05.

Sweat potassium mass were less in women than men in a half Ironman triathlon, respectively p=0.008. Men lost more sweat potassium in the Ironman compared to women, respectively p=0.044. (See Table 5.5)

Table 5.5. Average loss of sweat electrolytes estimated for during a half-Ironman and full-Ironman distances Race Male Female Variables Type Mean SD Mean SD Sweat Loss (L) Half 7.3 2.0 6.8 2.1 Full 16.5 4.6 14.5 4.0 Sweat Na+ (mEq) Half 334.1 110.7 251.9 140.8 Full 759.2 273.6 573.3 342.7 Sweat K+ (mEq) Half 42.7 10.6* 34.6 5.6 Full 95.7 22.5* 75.2 13.6 *Significantly different from females.

Electrolyte Content Relative to Body Mass

Body mass for each subject during the trial were equated to determine relative sweat electrolyte loss. The only finding, sweat sodium concentrations were higher in men compared to women, respectively p = 0.001. (Table 5.6)

Table 5.6. Relative sweat electrolyte loss during 45min testing Male Female Measures Mean SD Mean SD Sweat [Na+] (mEq/L·kg) 13.84 4.83* 15.46 6.74 Sweat Na+ (mEq·kg) 18.37 6.15 15.20 7.68 Sweat Na+ (mEq/hr·kg) 24.49 8.20 20.26 10.24 Sweat [K] (mEq/L·kg) 2.83 0.73 3.90 0.93 Sweat K (mEq·kg) 3.95 0.84 3.67 0.57 Sweat K (mEq/hr·kg) 5.27 1.13 4.89 0.76 *Significantly different from females.

Urine Measures

Electrolyte variability between male and female were found in 24 hr urine loss.

Men had higher urine sodium mass than women (196.2 ± 80.1 mEq vs 117.5 ± 49.5 mEq, respectively, p=0.002). No difference was found between sexes in urine mass potassium

(103.8 ± 40.3 mEq vs 104.0 ± 39.7 mEq, respectively, p=0.992). (Table 5.7) There was no difference in urine specific gravity (p=0.759, p=0.586) or urine color (p=0.824, p=1.000), urine volume (24hr·L), urine sodium and potassium concentrations.

Comparison of losses can be seen in Figure 6.2. One subject was a significant outlier and was not included in the sweat and urine data. Chloride content from sweat and urine were contaminated during the sweat analysis process and discarded. For all values in mEq/L, mEq/hr, and mEq, body size is the only difference.

Table 5.7. Twenty four hour urine electrolytes during laboratory testing Male Female Combination Measures Mean SD Mean SD Mean SD Urine [Na+] (mEq/L) 71.6 36.4 50.3 23.9 62.1 32.9 Urine Na+ (mEq) 196.2 80.1 * 117.5 49.5 161.2 78.2 Urine [K+] (mEq/L) 37.4 13.8 44.4 21.3 40.5 17.6 Urine K+ (mEq) 103.8 40.3 104.0 39.7 103.9 39.4 *Significantly different from females.

300 * Men 250 Women 200

150

100 Measure mEq Measure 50

0 Sodium Potassium

Figure 6.4. Twenty-four hour urine electrolytes during laboratory testing *Significantly different from females, p=0.002.

Figure 6.5. Differences iin male and female fluid turnover during testting *Significantly different from ffemales, p=0.001.

Electrolyte Turnoover and Nutrient Content

Net balance differrences were not found between male and femalle intake and loss of fluid and electrolytes ((see Table 5.8).

Table 5.8. Fluid and elecctrolyte net balances during 24 hours of recorrding Male Female Measures Mean SD Mean SD Water Net Balance -0.014 2.049 -0.465 1.377 Na+ Net Balance -1047.5 2228.7 -161.1 1435.33 K+ Net Balance 1732.4 2403.2 759.4 1722.77

During the 24 hoour dietary consumption, women consumed lesss kcal than men

(2888.57 ± 552.27 kcal vs 4434.92 ± 1800.82 kcal, respectively, p=0.0011), water (3.026 ±

1.216 L vs 4.594 ± 2.824 L, respectively, p=0.036) and sodium content (3588.7 ± 1004.7 mg vs 5081.2 ± 2277.2 mg, respectively, p=0.017). Sodium and water net balance was at an average loss compared to potassium at an average gain.(Table 5.9)(Figure 6.3) Women had a higher dietary carbohydrate than men (59.95 ± 8.48% vs 59.63 ± 9.42%, respectively, p=0.022), and women had a lower dietary fat percentage than men (16.23 ±

3.71% vs (17.52 ± 6.18%, respectively, p=0.001). Interestingly, men had a lower protein dietary percentage than women (22.85 ± 4.51% vs 23.45 ± 5.53%, respectively, p=0.033).

(Table 5.10 & Figure 6.4)

Table 5.9. Net balances for nutrients and fluids consumed over 24 h Male Female Measures Mean SD Mean SD Sweat Loss (L/24h) 1.39 0.31* 0.95 0.27 Urine Water Loss (L/24h) 3.36 0.08 2.64 0.03 Respiratory Water Loss (L/24h0.013 0.00† 0.013 0.00† Fecal Water Loss (L/24h) 0.123 0.00† 0.123 0.00† Water Intake (L/24h) 4.12 1.90* 3.03 1.22 Water Net Balance -0.014 2.049 -0.465 1.377

Sweat Na+ Loss (mg/24h) 1386.3 457.2 * 905.4 456.6 Urine Na+ Loss (mg/24h) 4511.5 1842.6 * 2700.2 1136.9 Fecal Na+ Loss (mg/24h) 18.4 0.00† 18.4 0.00† Na+ Intake (mg/24h) 5081.2 2277.2* 3588.7 1004.7 Na+ Net Balance -1047.5 2228.7 -161.1 1435.3

Sweat K+ Loss (mg/24h) 294.1 65.1* 219.6 35.4 Urine K+ Loss (mg/24h) 4060.1 1574.8 4065.4 1551.9 Fecal K+ Loss (mg/24h) 336.3 0.00† 336.3 0.00† K+ Intake (mg/24h) 6740.0 3204.2 5382.9 1376.4 K+ Net Balance 1732.4 2403.2 759.4 1722.7 *All values are based on 24 h *Significantly different from females, p<0.05. †Fecal and respiratory values are references values.

* * * Measure (L)

* *

Measure (g) Measure

Figure 6.6. Net BBalances of sodium, potassium and water durring the 24 hour observational perriod *Significantly differeent from females , p<0.05.

Table 5.10. Nutritional vvalues during 24 observational hours Male Female Coombination Measures Mean SD Mean SD Meaan SD Kcal 4434.92 1800.82* 2888.57 552.27 38225.75 1621.30 Water (L) 4.594 2.824* 3.026 1.216 3.955 2.41 Na+ (mg) 5081.2 2277.2* 3588.7 1004.7 4448.00 1971.80 K+ (mg) 6740.0 3204.2 5382.9 1376.4 61881.18 2667.83 % Carbohydrate 59.63 9.42* 59.95 8.48 59.776 8.91 % Fat 17.52 6.18* 16.23 3.71 17.001 5.32 % Protein 22.85 4.51* 23.45 5.53 23.110 4.88 *Significantly different for femmales, p<0.05.

Figure 6.7. Carbohydrate, fat, protein dietary intake during 24 h nutrient record

Acclimatization

Subjects’ geographic location a month prior to the study determined 6 who were living in average temperatures of >20 C. There were no differences between heat acclimatized and non-heat acclimatized subjects. Due to the small sample size we did not run the statistics on heat versus non-heat acclimatization. (See Table 5.11)

Table 5.11.Sweat electrolyte loss in heat acclimatized triathletes Heat Acclimatized Non-Heat Acclimatized Variables (n = 6) (n = 29) Mean SD Mean SD [Na+ ] (mEq/L) 29.2 17.9 47.5 17.6 Na+ (mEq) 35.1 20.4 54.2 21.5 Na+ (mEq/hr) 46.7 27.2 72.3 28.7 [K+] (mEq/L) 5.3 0.005 6.0 1.8 K+ (mEq) 6.5 2.2 6.7 1.6 K+ (mEq/hr) 8.6 2.9 9.0 2.1 Heat acclimatized defined as geographical temperature >20 C a month prior to testing

Exercise Intensity versus Electrolyte Loss

Subjects’ exercise intensity for the run test were split by ‘Fast Men’ (n=7), ‘Slow

Men’ (n=7), ‘Fast Women’ (n=7) and ‘Slow Women’ (n=6) to determine differences in sweat content. ‘Fast Men’ mean pace 6:29 min/mile, ‘Slow Men’ mean pace 8:32, ‘Fast

Women’ mean pace 7:11 min/mile and ‘Slow Women’ mean pace 8:45 min/mile. ‘Fast

Men’ lost more total wash-down potassium than ‘Fast Women’ (p=0.039) and ‘Fast Men’ lost more total wash-down potassium than ‘Slow Women’ (p=0.018). ‘Fast Men’ had a greater potassium loss rate than ‘Fast Women’ (p=0.039) and ‘Fast Men’ had a greater potassium loss rate than ‘Slow Women’ (p=0.018). (Table 5.12) When comparing sweat electrolyte content relative to body weight, the concentration of sweat sodium were higher in ‘Fast Women’ compared to ‘Slow Men’ (4.1 ± 0.4 mEq/L vs 2.6 ± 0.4 mEq/L, p=0.029) and ‘Slow Women’ compared to ‘Slow Men’ (4.5 ± 0.5 mEq/L vs. 2.6 ± 0.4 mEq/L, p=0.008).

Table 5.12. Sweat electrolyte loss relative to exercise intensity during 45 min of testing Exercise Male Female Variables Intensity Mean SD Mean SD Sweat [Na+] (mEq/L) Fast 43.7 7.9 40.6 28.4 Slow 41.5 16.5 49.2 14.5 Sweat Na+ (mEq) Fast 61.4 18.6 36.3 17.0 Slow 56.8 22.7 49.0 25.6 Sweat Na+ (mEq/hr) Fast 81.8 24.8 48.4 22.6 Slow 75.8 30.3 65.4 34.2 Sweat [K+] (mEq/L) Fast 5.9 1.1 6.2 1.4 Slow 5.4 0.7 5.6 1.4 Sweat K+ (mEq) Fast 8.2 2.0* 5.8 1.0 Slow 7.6 1.8 5.3 1.0 Sweat K+ (mEq/hr) Fast 10.9 2.6* 7.8 1.3 Slow 10.2 2.3 7.0 1.2 *Significantly different from ‘Fast Women’ and ‘Slow Women’, p<0.05.

Chapter 5

Discussion

The main finding of this study is that when triathletes exercise un-accustomed to a warm environment in ambient conditions 28.1 ± 0.5 C and 27.7 ± 4.6 % RH for 43 ± 4 minutes, physiological differences between men and women occurred.

Sweat Rate and Sweat Loss

Consistent findings in sweat rate and sweat loss for gender differences were the most profound. Men had higher sweat rates and sweat loss than women. There is contradictory literature whether or not sweat rate and loss differ between gender.9, 24

Similarly, evaluation during a sweat analysis trial 3-7 days prior to the Kailua-Kona

Hawaii Ironman race, men had a statistically significant higher absolute sweat rate than women (1.53 ± 0.36 vs 1.11 ± 0.38 L·h-1, respectively, p=0.001).9 This is similar to the current study which found absolute sweat rate differences between men and women (1.88

± 0.38 L·h-1 vs 1.34 ± 0.36 L·h-1, p=0.001, respectively).

Weight compared to sweat rate for men and females during the current study differences were not found.(See Table 5.3) Men may be physically larger and have a greater average body mass (76.1 ± 7.0 kg; 60.1 ± 5.4 kg) and overall surface area is greater than women, therefore an increased sweat area would be assumed. This could attribute to the men having larger sweat rates than women shown in the absolute sweat rates.

Water consumption in men was significantly more than women (4.594 ± 2.824 L,

3.026 ± 1.216 L, respectively, p=0.036) over the 24 hour diet intake, but not during exercise. (See Table 5.10) Men did consume more fluids compared to females in the 24

hour nutrient record; this behaviour may contribute to men resulting in higher sweat rates, due to consumption of fluids during exercise. Percent dehydration was not significantly different between genders (♂1.29 ± 0.70%, ♀1.05 ± 0.48%) after exercise, although sweat loss contributed to differences between genders. (See Table 5.3) Prior to the exercise testing subjects were not evaluated for pre-exercise percent dehydration. An increase in hydration or euhydration status can elicit greater sweat sensitivity or response during exercise.25 Men ingested more fluids during the 24 hour evaluation and sweat more than women, assuming men were in a greater hydration state than women; this would elicit a greater sweat response and overall sweat loss and rate.

Men and women still need to be aware of the increase in sweat production during exercise in order to prevent increase dehydration percentage. Pre exercise hydration status should be monitored for elite triathletes who need to perform in a warm environment.

Sweat Electrolyte Loss

Sweat loss resulted in men having a greater sweat sodium mass loss and a greater rate of sweat sodium loss than women. Men resulting in higher sweat sodium mass loss could be due to a higher amount of sweat loss, therefore increasing the amount of sodium content.

Sweat sodium and potassium mass and rate of loss were significantly different between men and women. When comparing sweat electrolyte losses, it is believed that this is the first study conducted that compared genders and found significant difference in rate and mass of sweat sodium and potassium. The previous observations could be due to consumption of nutrient variability, men consumed more sodium than women, and

therefore an increase in the amount of sweat sodium during exercise in a warm environment is an important finding. Men are losing more sodium during competition and training relative to sweat rate.

Men sweat loss and dietary intakes of water and sodium were significantly different from females (1.39 ± 0.31L/hr1 versus 0.95 ± 0.27 L/hr1; 4.594 ± 2.824 L versus

3.026 ± 1.216L). (See Table 5.3 and Table 5.10) Although, on average men and women could only sweat for 2 hr at the current sweat rate relative to their dietary intake to maintain a balance. Overall men and women water loss is relative to their dietary intake.

Modifications to the intake of fluids and electrolytes are warranted relative to the sweat loss.

Contradictory to the present study, research done by Pahnke et al., found there were no significant differences between men and women for sweat sodium concentration loss.9 Gender differences may not be found with absolute concentration of electrolyte loss but when comparing relative sweat sodium concentration loss gender differences were found. (See Table 5.6) Women’s average body mass is smaller than men (60.1 ± 5.4 kg versus 76.1 ± 7.0 kg), the current findings suggesting that men and women need to address fueling procedures differently. Although, only relative sodium loss differences were found between genders, the overall amount of electrolytes being lost is important to know for replenishment before, during and post exercise.

Urine sodium mass loss was significantly different between men and women

(4511.5 ± 1842.6mg, 2700.2 ± 1136.9mg). (See Table 5.7) As a result, intake of sodium of different concentrations has been shown to change the rate of reabsorption of the kidneys or interstitial fluid space and secretion through urine and sweat.26 During 30

minutes of exercise in the heat the reabsorption rate of sodium decreased significantly compared to an increase in secretion rate of sodium.27 The reabsorption rate of sodium at

86 percent during the lowest rate of sweat rate changed to 65 percent at the highest rate of sweat rate.27 The current study men consumed significantly more sodium and a had greater sweat rate compared to women, as a result caused the renal and kidneys to decrease the reabsorption rate of sodium, at which an increase in urinary sodium presented.

Half versus Full Ironman

When comparing half and full Ironman triathlon race times, gender differences were found with calculated predicted electrolyte loss. Race time was incorporated into the calculated estimates. Predicted potassium variability was seen in the half and full

Ironman between genders, resulting in a significant increase in predicted sweat potassium loss compared to women in the half-Ironman and full- Ironman (669.6 ± 415.2 mg,

1352.3 ± 218.1 mg; 3741.0 ± 880.2mg, 2938.5 ± 529.9mg). (See Table 5.5) Estimated sweat loss during a half and full ironman race were not different between gender. This indicates men and women can use their current fueling procedure and apply to training and racing resulting in a balance between sodium and water.

Potassium loss seen during the half- and full-Ironman could be a result of finish times for males and females, on average males complete the half- and full-Ironman faster than females (258 ± 24 minutes, 282 ± 19 minutes; 590 ± 61 minutes, 615 ± 41 minutes).

Relative to the time, each gender on average took to complete the race, would increase the predicted concentration of sweat potassium, or the result of sweat potassium loss was significantly different between genders from the exercise testing. The variability of

potassium sweat loss may have carried over to the calculated predict finish time for half- and full-Ironman.

Costill found no difference in sweat K+ loss during a high K+ diet 80 meq/day versus a low K+ diet 25 meq/day.28 The same study found the amount of potassium intake during a subject’s diet is independent to sweat K+ loss and during repeated days of heavy intense exercise potassium net balance is dependent on potassium consumption.28

Consumption of potassium during the race would not be a predictor of potassium differences between males and females.

Electrolyte Turnover and Nutrient Content

Elite triathletes were maintaining an overall slightly negative net balance for water and electrolytes during training. Men’s average intake of sodium decreased the fluid net balance compared to females.12, 14-15 It is hypothesised that when increasing sodium intake, this will result in conservation of fluids, to maintain homeostasis. Men in the current study replaced losses via sodium ingestion to offset their sodium losses and as result helped maintain fluid balance.

During the evaluation of nutrients through diet records; females ate less food and consumed overall less nutrients then men. Contradictory to the current study, nutrients consumed during the Hawaii Ironman triathlon done by Pahnke et al, found no significant differences between sexes. Although, the food was self-reported at the 56-mile mark of the bike segment, after the bike and post-race.9 It can be hypothesized that during a race versus training, consumption of food may vary. The evaluation recorded nutrients per kg of weight.

Consumption of sodium during exercise or training can change the rate of reabsorption of the kidneys or interstitial fluid space and secretion through urine and sweat.26 During 30 minutes of exercise in the heat, the reabsorption rate of sodium decreased significantly compared to an increase in secretion rate of sodium.27 This due to the process of enhanced glandular/renal reabsorption to conserve sodium within the body.

28, 29 Men had a significantly increased intake of sodium; although, this resulted in increased sodium sweat loss and urine sodium loss compared to women. Independent of sodium intake, the men’s body did not reabsorb sodium compared to women. Another hypothesis could be a result of men consuming additional sodium; therefore, the body would excrete the excess sodium.

Most astonishing are the net balance values for sodium net balance between male and females (-1047.5 ± 2228.7mg, -161.1 ± 1435.3mg), (Table 5.8) although there were no significant differences between genders, males produced an increase of 84% negative net balance compared to females. Similarly seen between male and female (1732.4 ±

2403.2mg, 759.4 ± 1722.7mg) for potassium net balance, males produced an increase of

56% positive net balance compared to females, no significant differences were found.

Costill found changes in dietary intake of K+ will increase the conservation of water and K+ net balance during long endurance exercise.28 This finding is similar to the current study, where men consumed a large amount potassium and maintained in a positive net balance. Men nor women do not need to be concerned about increasing potassium intake, there may be a concern on the amount of sodium consumed related to potassium lost. Consequently, consuming high sodium content replacement drink after exercise results in an increase in potassium loss in urine.30 Men consumed a significant

amount of sodium, which may have resulted in a large amount of potassium lost in urine.

Although, men and women did lose relatively the same amount of potassium in urine, women did not consume a significant amount of sodium. Further research needs to address gender differences between intake, loss and net balance of fluids and electrolyte content.

During the recovery phase after exercise, intake of sodium in different concentrations will affect the net water balance post exercise. Higher consumption of fluids containing sodium sustains a greater net fluid balance compared to the other drinks.30 The influence of sodium replacement occurring post exercise will have a positive effect on the conservation of water within the human body.

In summary, men consumed more sodium than women; conservation of fluids should have been seen by decreasing the negative net balance in males. Overall men did not have a significantly large negative net balance therefore as a result of consuming more sodium decreased fluid net loss.

Top Finishers versus Bottom Finishers

When comparing top and bottom finishers, top finishers had less body fat percentage, higher speed and more completed races than bottom finishers. Page et al. observed no correlation between weight change and running time during an ultra- endurance mountain run.31 Although, the fastest male runner (winner of the race) lost

2.4% of his body weight and the fastest female lost 3.9% of her body weight, average race finish time 7 hour 58 minutes. Female body weight loss higher than 3% did not affect finish time.31

Relevant to the current research, the top finisher male completed the Ironman in 8 hours 36 minutes, and lost 1.7% body weight during the testing. The top female finisher completed the Ironman 9 hours 6 minutes and lost 2.07% body weight during the testing.

The female finishers lost more body weight percentage then the fastest male. No other study compared Ironman finish times, body fat percentage and speed at which the subjects exercised during the testing comparing top or bottom finishers.

Comparable to another study done at an ultra-endurance race, athletes lost a significant amount of weight, a mean of 3.7kg (5.2 percent). 32, 33 Sweat rates that equaled ingestion rates did affect cycling performance during the race. Surprisingly enough higher levels of dehydration did not affect run performance or finish times. Athletes with the highest levels of weight loss had the fastest run times.33-35

Statistical analysis found no significant differences comparing top and bottom finishers for electrolyte content in urine or sweat. (See Table 5.2) One hypothesis could be that the subjects are consuming enough nutrients and fluids in preparation for race length.

Exercise Intensity versus Electrolyte Loss

Men do race at a relatively higher pace (mean difference pace > 1 min/mile), therefore intensity of subjects exercising do need to be controlled in order to determine whether a difference exists between males and females. ‘Fast Men’ had larger potassium loss than ‘Fast Women’ and ‘Slow Women’ (8.2 ± 2.0 mEq versus 5.8 ± 1.0 mEq and 5.3

± 1.0 mEq) and potassium loss rate (10.9 ± 2.6 mEq/h versus 7.8 ± 1.3mEq/h and 7.0 ±

1.2 mEq/hr). Only differences in potassium loss were analytical of intensity chosen by the subject. More research needs to be addressed on intensity differences amongst athletes.

Practical Implications

The implications of the study are to assist athletes to utilize the findings in reference to properly hydrate and replace electrolytes during training and competition.

Endurance athletes can adjust to their own fluid and sodium loss to accurately replenish.

Maintaining proper fluids during activity can positively or negatively influence homeostatic variability. Nutrient content before, during exercise and the recovery phase are important to maintain homeostatic variability. Pre, during and post exercise fluid and fuel will affect the output of sweat electrolytes. The consensus of gender differences will help in producing new variables of proper hydration and replacement of electrolytes recovery and intake appropriate for male and females separately.

Limitations and Future Directions

Future directions are to evaluated sodium turnover in elite triathletes comparing values in different environments. The values will help to determine a validated equation to help triathletes determine their own sodium turnover values without having to go through the physical testing processes. Testing other athletes in different sport categories to develop further understanding in sodium turnover can help to develop a chart similar to the ACSM fluid/sweat chart.36 The observation of physiological differences between male and females as to the reason for significant differences in sweat rate and sweat sodium loss in men, warrant future research. Weight relative to sweat loss should have been compared to determine if differences were found in kg/L. Research by Phanke et al. found no significant differences between males and females when considering weight.9

Further research analysis on sweat potassium loss in half versus full Ironman between genders and the physiological disruptions needs to be evaluated. More research in the

area of performance and the effects of diet intake in triathletes or gender differences to determine increased performance effects need to be evaluated further.

Limitations and errors can occur during a field study although valuable information can be found compared to that of a laboratory setting. The research was conducted as a field study which doesn’t allow for reliability and consistency. During a field study each researcher may have many roles or an assessment tool may have many researchers conducting the technique to gather values, resulting in inconsistencies. In the present study, the self-reporting of nutrients could have caused error. The diet recording was not controlled for consistency and thoroughness. Each subject’s perception of measuring foods consumed is not consistent between subjects. The subjects were free to consume their own or NY Giants Timex Performance Center nutrients during the testing procedures. Food, electrolytes were not provided by the research staff. As a result, many subjects were free to consume foods high in sodium, therefore gender differences could be due to males consuming high sodium foods compared to females. If subjects ate the same foods gender differences would result in an increased validity. The NY Giants

Timex Performance Center could not provide use with the exact measures for the ingredients in all foods. Assumptions on measurements were made to accurately determine nutrient values. Some subjects took supplements which had patents and the companies of the products would not release the information on the supplement contents.

This would affect nutrient content. Two subjects needed to redo their test due to urine excretion during the testing time. This would affect the 24 hour urine collection and overall electrolyte concentration. Majority of subjects did not properly record or hand in the 24hr urine record form. Implications caused a disruption to overlap of the 24 hour

urine, 24 hour diet. Consumption of food before testing would affect the electrolyte content; therefore, if a subject tested on the first day and recorded the diet post-exercise, nutrients post would not accurately depict intake. The overlap of the 24 hour urine, 24 hour diet was not consistent, resulting in inconsistent intake and loss to determine net balance. There is some expected error when collecting wash down test samples, and collecting all sweat loss during exercise. Subjects would sweat and the researchers would do their best to collect all sweat loss, although some sweat was lost to the floor or from removal and dressing of clothing to weigh before the wash.

Conclusion

In conclusion, this study demonstrated that men have a greater sweat sodium mass loss than women as a result of having a greater sweat rate. Women had a decreased sweat K+ mass loss compared to men, equally both genders had a positive K+ net balance.

Men had greater urine and sodium mass loss than women and men consumed more dietary sodium but resulted in a negative net balance. In summary, men need to consume more sodium due to an increased sweat rate and overall sweat loss, while women need to focus on individualizing their replacement and recovery of fluids and electrolytes lost.

References

1. Ironman & Ironman 70.3. http://ironman.com/events/#axzz28EbQ1QIj. Updated 2012. Accessed October 3, 2012.

2. Challenge Roth. http://www.challenge-roth.com/en/index.html. Updated 2012. Accessed October 3, 2012.

3. Bates GP, Miller VS. Sweat rate and sodium loss during work in the heat. J Occup Med Toxicol. 2008;3(4):1-6.

4. Nadel ER. Body fluid and electrolyte balance during exercise: competing demands with temperature regulation. In: Thermal Physiology. edited by Hales JRS. New York : Raven. 1984;365-376.

5. Rowell LB. Cardiovascular adjustments to thermal stress. In: Handbook of Physiology. The Cardiovascular System. Peripheral Circulation and Organ Blood Flow. Bethesda, MD: Am Physiol Soc. 1983;2(3)(2)(27):967-1023.

6. Bedford JJ, Bagnasco SM, Kador PF, Harris WF, Burg MB. Characterization and purification of a mammalian osmoregulatory protein, aldose reductase, induced in renal medullary cells by high extracellular NaCl. J Biol Chem. 1987;262:14255- 14259.

7. Glace BW, Murphy CA, McHugh MP. Food intake and electrolyte status of ultramarathoners competing in extreme heat. J Amer Col Nutri. 2002;21(6):553- 559.

8. Stofan JR, Zachwieja JJ, Horswill CA, Murray R, Anderson SA, Eichner ER. Sweat and sodium losses in NCAA football players: a precursor to heat cramps?. Inter J Sport Nutri Exerc Meta. 2005;15:641-652.

9. Pahnke MD, Trinity JD, Zachwieja JJ, Stofan JR, Hiller WD, Coyle EF. Serum sodium concentration changes are related to fluid balance and sweat sodium loss. Med Sci Sports Exerc. 2010; 42(9):1669-1674.

10. Twerenbold R, Knechtle B, Kakebeeke TH, Eser P, Müller G, von Arx P, Knecht H. Effects of different sodium concentrations in replacement fluids during prolonged exercise in women. Br J Sports Med. 2003;37:300-303.

11. Kirby CR, Convertino VA. Plasma aldosterone and sweat sodium concentrations after exercise and heat acclimation. J Appl Physiol. 1986;61(3):967-970.

12. Maughan RJ, Owen JH, Shirreffs Sm, Leiper JB. Post-exercise rehydration in man: effects of electrolyte addition to ingested fluids. Eur J Appl Physiol. 1994;69:209-215.

13. Nose H, Mack GW, Shi X, Nadel ER. Shift in body fluid Compartments after dehydration in humans. J Appl Physiol. 1988;65(1):318-324.

14. Shirreffs SM, Maughan RJ. Volume repletion after exercise-induced volume depletion in humans: replacement of water and sodium losses. Am J Physiol. 1998;274:F868-F875.

15. Maughan RJ, Leiper JB. Sodium intake and post-exercise rehydration in man. Eur J Appl Physiol. 1995;71:311-319.

16. Wilkinson DM, Carter JM, Richmond VL, Blacker SD, Rayson MP. The effect of cool water ingestion on gastrointestinal pill temperature. Med Sci Sports Exerc. 2008;40:523.

17. Armstrong LE, Maresh CM, Castellani JW, et al. Urinary indices of hydration status. Int J Sport Nutr. 1994;4:265–279.

18. Jackson A.S, Pollock M.L. Generalized equations for predicting body density of men. British J Nutr. 1978;40:497-504.

19. Jackson A.S, Pollock M.L, Ward A. Generalized equations for predicting body density of women. Med Sci Sport Exercise. 1980;12:175-182.

20. Siri W.E. Body composition from fluid space and density. In J. Brozek & A. Hanschel (eds.), Techniques for measuring body composition (pp. 223-244). Washington, DC: National Academy of Science.

21. Borg GAV. Psychophysical bases of perceived exertion. Medicine and Science in Sports and Exercise. 1982;14(5):377-381.

22. Armstrong LE and Casa DJ. Methods to evaluate electrolyte and water turnover of athletes. Athletic Training and Sports Health Care. 2009;1(4):169-179.

23. Armstrong LE and Casa DJ. Methods to evaluate electrolyte and water turnover of athletes. Athletic Training and Sports Health Care. 2009;1(4):169-179.

24. Buono MJ, Claros R, DeBoer T, Wong J. Na+ secretion rate increases proportionally more than the Na+ reabsorption rate with increases in sweat rate. J Appl Physiol. 2008;105:1044-1048.

25. Armstrong LE, Maresh CM, Gabaree CV, Hoffman JR, Kavouras SA, Kenefick RW, Castellani JW, Ahlquist LE. Thermal and circulatory responses during exercise: effects of hypohydration, dehydration, and water intake. J Appl Physiol. 1997;82(6):2028-2035

26. Maughan RJ, Leiper JB. Sodium intake and post-exercise rehydration in man. Eur J Appl Physiol. 1995;71:311-319.

27. Buono MJ, Claros R, DeBoer T, Wong J. Na+ secretion rate increases proportionally more than Na+ reabsorption rate with increases in sweat rate. J Appl Physiol. 2008;105:1044-1048.

28. Costill DL. Sweating: Its composition and effects on body fluids. Ann N Y Acad Sci. 1977;301:160-174.

29. Kirby CR, Convertino VA. Plasma aldosterone and sweat sodium concentrations after exercise and heat acclimation. J Appl Physiol. 1986;61(3):967-970.

30. Shirreffs SM, Maughan RJ. Volume repletion after exercise-induced volume depletion in humans: replacement of water and sodium losses. Am J Physiol. 1998;274:F868-F875.

31. Page AJ, Reid SA, Speedy DB, Mulligan GP, Thompson J. Exercise-associated hyponatremia, renal function, and nonsteroidal anti-inflammatory drug use in an ultraendurance mountain run. Clin J Sport Med. 2007;17:43-48.

32. Sharwood KA, Collins M, Goedecke JH, Wilson G, Noakes TD. Weight changes, medical complications, and performance during an ironman triathlon. Br J Sports Med. 2004;38:718-724.

33. Sharwood KA, Collins M, Goedecke JH, Wilson G, Noakes TD. Weight changes, sodium levels, and performance in the south african ironman triathlon. Clin J Sport Med. 2002;12:391-399.

34. McConell GK, Stephens TJ, Canny BJ. Fluid ingestion does not influence intense 1-hour exercise performance in a mild environment. Med Sci Sports Exerc. 1999;31:386-392.

35. Noakes TD, Sharwood K, Collins M, Perkins DR. The dipsomania of great distance: water intoxication in an ironman triathlete. Br J Sports Med. 2004;38(16)1-5.

36. American College of Sports Medicine. Position stand: exercise and fluid replacement. Med Sci Sports Exerc. 1996;28(1):ii-iv.

Appendix A

HUMAN PERFORMANCE LABORATORY MEDICAL HISTORY QUESTIONNAIRE

Study Timex Training Camp '12

Name Sex Age DOB

Street

City State Zip Phone

Email PLEASE ANSWER ALL OF THE FOLLOWING QUESTIONS AND PROVIDE DETAILS FOR ALL "YES" ANSWERS IN THE SPACES AT THE BOTTOM OF THE FORM.

YES NO Has your doctor ever said that you have a heart condition and that you should only do physical activity recommended by 1. a doctor?

2. Has your doctor ever denied or restricted your participation in sports or exercise for any reason? 3. Do you ever feel discomfort, pressure, or pain in your chest when you do physical activity?

4. In the past month, have you had chest pain when you were not doing physical activity?

5. Do you lose your balance because of dizziness or do you ever lose consciousness?

6. Does your heart race or skip beats during exercise?

7. Has a doctor ever ordered a test for you heart? (i.e. EKG, echocardiogram)

8. Has anyone in your family died for no apparent reason or died from heart problems or sudden death before the age of 50?

9. Have you ever had to spend the night in a hospital?

10. Have you ever had surgery?

11. Please check the box for any of the following illnesses with which you have been diagnosed or for which you have been treated.

High blood pressure Elevated cholesterol Diabetes

Asthma Epilepsy (seizures) Kidney problems

Bladder Problems Anemia Heart problems

Coronary artery disease Lung problems Chronic headaches

YES NO 12. Have you ever gotten sick because of exercising in the heat? (i.e. cramps, heat exhaustion, heat stroke)

13. Have you had any other significant illnesses not listed above?

14. Do you currently have any illness?

15. Do you know of any other reason why you should not do physical activity?

Please list all medications you are currently taking. Make sure to include over-the-counter medications and birth control 16. pills.

Drugs/Supplements/Vitamins Dose Frequency (i.e. daily, 2x/day, etc.)

DETAILS:

17. Please list all allergies you have.

Substance Reaction

Age 18. Have you smoked? If yes, #/day If you've quit, what age? YES NO Started Cigarettes

Cigars

Pipes

19. Do you drink alcoholic beverages? If yes, how much? How often?

20. Do you have a family history of any of the following problems? If yes, note who in the space provided.

High blood pressure Heart disease

High cholesterol Kidney disease

Diabetes Thyroid disease

21. Please check the box next to any of the following body parts you have injured in the past and provide details.

Hip Calf/shin Head Shoulder Neck Thigh Upper back Knee Upper arm

Lower Ankle Elbow back

Chest Foot Hand/fingers

YES NO

22. Have you ever had a stress fracture?

23. Have you ever had a disc injury in your back?

24. Has a doctor ever restricted your exercise because of an injury?

25. Do you currently have any injuries that are bothering you?

26. Do you consider your occupation as? Sedentary (no exercise)

Inactive-occasional light activity (walking)

Active-regular light activity and/or occasional vigorous activity (heavy lifting, running, etc.)

Heavy Work-regular vigorous activity

27. List your regular physical activities

When did you Activity How often do you do it? How long do you do it? start?

ADDITIONAL DETAILS:

Appendix B Timex Training Camp - Washing Instructions

As you may know, the UConn Research Team that was in Kona will be providing whole body sweat wash-downs to determine electrolytes lost in sweat during exercise. They will be conducting the sessions on Friday and Saturday. If you plan on participating in the testing, please bring a pair of workout clothes, (i.e. a sports bra, t-shirt and shorts or your normal workout attire) with you to the first meeting on Thursday. They will collect and wash the clothes to ensure they are free of any detergents which can affect their measurements. If you have any questions of concerns about the processes please contact:

Rob Huggins: [email protected] 203.804-2316

Amy Mausser: [email protected] 860.465.2394 Timex Training Camp - Washing Instructions

We ask that all athletes participating in the whole body wash-down exercise to shower the morning of their scheduled session. Instructions and guidelines on the washing procedure are listed below:

1) Please wash WITHOUT soap for a good 15-20mins to make sure that all substrates are

rinsed off

2) Thoroughly rinse your hair and your skin

3) When you are done washing, please towel dry completely

4) Please make sure that your hair is completely dry before coming to your scheduled

session

(Hair dryers will be provided in case hair is not completely dry)

5) Please NO make-up, perfumes, deodorant, or any other application of products

before the testing procedures

Appendix C

Timex Training Camp – Tc Pill Instructions

1. Make sure you are ingesting the Tc Pill 8- 12 hours to allow for optimal time for the pill to be located in the small intestine 2. Please remove the pill from envelope, and remove the label and magnet from the pill. This will activate the pill. Only ingest the white pill, DO NOT ingest the label, magnet or the entire envelope 3. If you know your GI tract moves faster, if your scheduled session is in the afternoon, you may take the pill the morning of the exercise bout 4. You do not need to return the pill; it will be discarded within your contents 5. If you cannot swallow the pill, due to the size or gag reflex, another option will be to insert the pill into the rectum before you proceed 6. If you took the pill the night before and it was in your stool the next morning please let us know so we can make other arrangements 7. Make sure to not place this pill near any metal surfaces or cell phones. This deactivates the pill

Appendix D

Timex Training Camp - Survey

1. What geographic location did you perform your training in the last month? (circle one)

New England: Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, Connecticut

Mid-Atlantic: New York, Pennsylvania, New Jersey

East North Central: Wisconsin, Michigan, Illinois, Indiana, Ohio

West North Central: Missouri, North Dakota, South Dakota, Nebraska, Kansas, Minnesota, Iowa

South Atlantic: Delaware, Maryland, District of Columbia, Virginia, West Virginia, North Carolina, South Carolina, Georgia, Florida East South Central: Kentucky, Tennessee, Mississippi, Alabama

West South Central: Oklahoma, Texas, Arkansas, Louisiana

Mountain: Idaho, Montana, Wyoming, Nevada, Utah, Colorado, Arizona, New Mexico

Pacific: Alaska, Washington, Oregon, California, Hawaii Other: ______

2. What time of day did you typically train in the last month? (circle most frequent)

Early Morning (4-7am) Early Afternoon (1-3pm) Mid Morning (7-9am) Mid Afternoon (3-5pm) Late Morning (9-11) Evening (5-8pm) Noon (11-1pm) Night (>8pm)

3. Currently, at what elevation do you train? (Please write city and state, if

uncertain) ______

4. Where do you typically train for the swim? (circle most frequent) Pool Pond Lake Ocean Other: ______

5. Have you recently trained in a hot environment, if so, did you do anything to prepare for training? Yes / No (circle one) (For Example: wear certain clothing, drink more water, change your diet)

Explain:______

______6. Have you attended a training camp in the last month? Yes / No If so, please provide details (i.e. length, location):______7. What were your average yardages per week in the last month? Swim ______Bike ______Run ______8. What was your longest/shortest distance of each discipline in the last month? Swim______/ ______Bike ______/______Run ______/ ______9. How many times a week did you train each discipline in the last month? Swim ______Bike ______Run ______10. What was your average type/distance of training for the last month? (Circle Type, Provide Distance) Run: Tempo ______Cycle: Tempo ______Swim: Technique ___ Speed ______Speed ______Speed ______Base______Base ______Base ______11. How often do you take a recovery day? ______If so, what does it contain: ______12. Do you resistance train? Yes / No On average, how many hours a week? ______13. On average, how many minutes during the day do you stretch: ______14. Do you attend HOT Yoga? Yes / No On average, how many hours a week? _____ 15. What is your fastest time: Half Ironman ______Ironman ______Overall Placing: ______Overall Placing: ______Age Group: ______Age Group: ______16. How many of the following race distances have you completed? Half Ironman ______Ironman ______

17. For an Ironman, what is your fastest time for each discipline? Swim ______Bike ______Run ______

18. What Ironman(s) or races do you plan to complete this 2012 year? (list below) ______19. How would you rate your nutrition health: Above Average / Average / Below Average Please Circle Yes / No 20. Do you add salt to your meals? Yes / No If so, how much ______

21. Have you ever suffered from heat stroke? Yes / No If so, when______

22. Have you every suffered from hyponatremia? Yes / No If so, when ______

23. Have you ever suffered from heat syncope? Yes / No If so, when ______

24. Do you plan on competing at Lake Placid for the 2012 Ironman? Yes / No Would we be able to contact you for further research studies? Yes / No

Appendix E

[ ] Subject showered w/o soap or shampoo, no deodorant Initials

[ ] Subject ingested core temperature pill last night Initials

Informed Consent and Related Forms

Informed Consent Signed by Subject and Researcher Initials

Medical History Completed and No Exclusionary Criteria Initials

Exercise History Form Completed Initials

Heart Rate Form Completed Initials Demographics

Sex: Male / Female Age _____ Height _____ cm

Personal Records: ½ Ironman _____ : _____ Ironman _____ : _____ Pre-Exercise Data

Chest/Triceps Abdomen/Suprailiac Thigh 1. _____ mm 1. _____ mm 1. _____ mm Initials 2. _____ mm 2. _____ mm 2. _____ mm (3.) _____ mm (3.) _____ mm (3.) _____ mm

Pre-exercise Spot USG ______Pre-exercise Spot Urine Color ____

If 24 hr urine collected: Empty Jug Weight ______g

Weight ______g Color______USG______

Nude Body Weight ______kg Initials

Watch # ______5 minute supine HR ______bpm

Drink # Full Bottle Pre-Weight

1 g

2 g

3 g

Bike / Treadmill Exercise Start Time _____:_____ Initials

Relati Speed Card Over Ther Ambient Ti Core Predicte Actual Leg ve or io all mal Tempera me Temp d HR HR RPE Humid Watts RPE RPE Scale ture ity

0 ______b ______min °C pm bpm ______°C _%

5 ______b ______min °C __ pm bpm ______

10 ______b ______min °C __ pm bpm ______

15 ______b ______min °C __ pm bpm _____°C _%

20 ______b ______min °C __ pm bpm ______

25 ______b ______min °C __ pm bpm

30 ______b ______min °C __ pm bpm ______°C %

35 ______b ______min °C __ pm bpm

40 ______b ______min °C __ pm bpm ______

45 ______b ______min °C __ pm bpm _____°C %

50 ______b ______min °C __ pm bpm ______

55 ______b ______min °C __ pm bpm

Exercise End Time ____:____ Initials Total Minutes ______min Distance Covered ______mi

Drink # Bottle Post-Weight Water Consumed (Pre – Post = ) 1 ______g ______g

2 ______g ______g

3 ______g ______g

Post-Exercise Data

Nude Body Weight ______kg Initials Body Mass Loss _____kg (Pre weight – Post weight)

If subject urinates during exercise: (USG)______(Urine Color) ____

(Urine Jug) Pre ______g - Post ______g = Urine Loss ______g

Total Rinse Water

Jug A Jug B Total

______+ ______= ______

Rinse Water Initials

Sample 1: Na+ ______mmol/L K+ ______mmol/L Cl- ______mmol/L

Sample 2: Na+ ______mmol/L K+ ______mmol/L Cl- ______mmol/L

24 Hour Urine Initials

Sample 1: Na+ ______mmol/L K+ ______mmol/L Cl- ______mmol/L

Sample 2: Na+ ______mmol/L K+ ______mmol/L Cl- ______mmol/L

Appendix F 24-Hour Urine Collection

Subject: ______

Start Date: ______Time of 24-hr Initiation: ______AM / PM

End Date: ______Time of last void: ______AM / PM

Instructions:

1. Please void your bladder into the toilet.

2. The 24-hr clock officially starts at this time. Please record the time in the space above.

3. All following urinations for the next 24-hours must be collected into the jug, including those in the middle of the night. Please do not carry these jugs around while at the Timex Performance Center, instead, please leave your jug in a restroom to be used when you urinate throughout the training camp. Take them with you when you leave at the end of the day to the hotel.

4. At the end of the 24-hr period, please “force-urinate” anything that you can into the jug and record the time in the space above.

5. The collection is now complete. Please keep your jug capped and return it at the time of your testing, unless instructed otherwise.

If you need another urine jug because yours is getting full, please contact Riana at (716) 348-9306 or Rob at (203) 804-2316.

Thank you!

Questions? Please call us: Riana at (716) 348-9306 or Rob at (203) 804-2316.

Appendix G

Subject: ______

Nutrition & Hydration Questionnaire

*This questionnaire asks questions that pertain to your habitual nutrition and hydration habits, as well as workout and race-day practices. Please answer as completely as possible.

1) What is your current weight? ______and height? ______

2) What is your ideal weight? ______

Please place a check before the sentence that most accurately applies to you.

______I am comfortable at my current weight.

______I am trying to gain weight.

______I am trying to lose weight.

3) The following questions refer to your daily meal and snack intake.

On a typical day, how many meals do you consume? ______

How many snacks do you consume (excluding pre/post workout snacks)? ______

4) The following questions refer to your meal and snack intake before training workouts and races.

What is your typical pre-race meal? Please include quantities and the amount of time it is consumed before the race. (Include foods and beverages)

______

What is your typical pre-race snack? Please include quantities and the amount of time it is consumed before the race. (Include foods and beverages)

______

If different than race day, what is your typical pre-workout snack? Please include quantities and the amount of time it is consumed before the workout. (Include foods and beverages)

______

5) The following questions refer to your intake after training workouts and races.

What is your typical post-race snack? Please include quantities and the amount of time it is consumed before the race. (Include foods and beverages)

______

What is your typical post-race meal? Please include quantities and the amount of time it is consumed before the race. (Include foods and beverages)

______

If different than race day, what is your typical post-workout snack? Please include quantities and the amount of time it is consumed before the workout. (Include foods and beverages)

______

6) The following questions refer to your food and beverage intake during workouts.

What do you eat and/or drink during training workouts? Please explain your food and beverage practices during all training workouts (run, swim, bike, etc) and provide details when possible.

______

What do you eat and/or drink during races? Please explain your food and beverage practices during each arm of the race (run, swim, bike, etc) and provide details when possible.

______

7) Are you taking any kind of supplement or over the counter (OTC) medication?

Yes No

If you answered yes to question 7, please list and describe any supplement or OTC medication you are currently taking:

Type Brand Dose/Amount Frequency

Vitamin/Mineral

Anti-Inflammatory

Medications

Diet Pills

Antioxidants

Other

8) Do you consume supplements to enhance recovery? Yes No

If yes, please provide the details of the timing, type and amount, including brands if known.

Type Brand Amount Timing Frequency

9) Do you consume caffeine? Yes No

If yes, how much, how often, and what in forms (coffee, tea, gels, etc)?

______

10) Are you allergic to any food(s) or beverage(s)? Yes No

If yes, please specify.

______

11) Are you lactose intolerant? Yes No

If you are lactose intolerant, do you still consume milk products? Yes No

12) Do you avoid any specific food or beverage due to personal or religious preferences? Yes No

If yes, please specify (include dislikes).

______

13) Do you avoid gluten? Yes No

Are you gluten intolerant? Yes No

Have you been diagnosed with Celiac? Yes No

14) Do you consume fish? Yes No

If yes, how much and how often? ______

15) Do you eat red meat?

If yes, how much and how often? ______

16) Please include any further details you would like to provide about your diet (past or present).

______

Appendix H

______

*Please circle the number next to each statement that corresponds to how it applies to you* Strongly Strongly Disagree Neutral Agree Disagree Agree

I worry about becoming dehydrated 1) 1 2 3 4 5 during a race 2) I drink only when I am thirsty 1 2 3 4 5 3) Knowing my sweat rate is important 1 2 3 4 5 I believe drinking fluids will protect me 4) 1 2 3 4 5 from heat illness 5) I have an established hydration plan 1 2 3 4 5 6) I drink when the race makes it possible 1 2 3 4 5 I would perform better if I drank a 7) 1 2 3 4 5 higher volume 8) I drink as much as I can 1 2 3 4 5 I drink when I sense that I am 9) 1 2 3 4 5 dehydrated I believe drinking fluids will enhance 10) 1 2 3 4 5 performance 11) I purposefully overhydrate prior to races 1 2 3 4 5 I worry about drinking too much during 12) 1 2 3 4 5 a race I pay more attention to hydration than 13) 1 2 3 4 5 food consumption My effort level during a race dictates 14) 1 2 3 4 5 when I can drink I believe consuming sports drinks 15) improves my performance more than 1 2 3 4 5 consuming water I pour water over my body because I 16) 1 2 3 4 5 believe it will improve my performance

If you agree or strongly agree to the question above, please describe in the space below where and how frequently you pour the water over your body.

Please describe what drives you to drink.

______

Please describe what is your hydration plan.

______

Please include any further details you would like to provide about your hydration practices (past or present).

______

Appendix I

DIETARY FOOD RECORD INSTRUCTIONS

• Please record your dietary intake for 24 hours.

All foods and beverages consumed should be recorded.

Be very specific. Make sure you include: the type of food/beverage the amount of each food/beverage the preparation method (i.e., fried, baked) the brand name of the food (if applicable) the time it was eaten the restaurant you ate it at (i.e., Subway, Applebees, Red Robin)

Record food/beverage consumption after each meal/snack instead of waiting until the end of the day.

Use nutrient descriptors (e.g., low-fat, low-carb, fat-free, light, reduced calorie, etc.).

Include miscellaneous items such as condiments (ketchup, salad dressing, mayonnaise, jams, creams, sugar), and chewing gum.

Remember to include cooking oils.

List combination dishes as separate ingredients (i.e., subway sandwich: 6 inch wheat roll, ¼ cup shredded lettuce, 3 oz grilled chicken breast, 2 Tbsp hot peppers, 2 Tbsp black olives, 1 Tbsp sweet onion sauce)

Date: Example

Calories from Detailed food/beverage description: brand Time name, restaurant, method of preparation, Amount package (if flavor, condiments, etc. known) ! " #$%#&#'( +, )" " * - ./ 0 ,&/1! " ) * . 2 2 3 ' , 41 $( . % ! / / 5 / ) * 6 " ./ 7 / " ,/ 4 &/ 89 .: " $ 1 ( ( ; &"" # <, (" / / 4, 1 = = " $ : < 4 9 / 2 0 > 7 # + = 8- ./ . / ) * <,? ;5 " , $ / ) 8@ / # " # */ )* A ./9 & " $ #B . % ; C,? C1 %77 / # 1 8 D< C1 Comments:

Name: ______Date:

Calories from Detailed food/beverage description: brand Time name, restaurant, method of preparation, Amount package (if flavor, condiments, etc. known)

Comments: