Handgrip Fatigue and Forearm Girth in Intermediate Sport Rock Climbers

UNLV Theses, Dissertations, Professional Papers, and Capstones

August 2018

Grace Antoinette Macdonald

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Repository Citation Macdonald, Grace Antoinette, "Handgrip Fatigue and Forearm Girth in Intermediate Sport Rock Climbers" (2018). UNLV Theses, Dissertations, Professional Papers, and Capstones. 3366. http://dx.doi.org/10.34917/14139886

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This Thesis has been accepted for inclusion in UNLV Theses, Dissertations, Professional Papers, and Capstones by an authorized administrator of Digital Scholarship@UNLV. For more information, please contact [email protected]. HANDGRIP FATIGUE AND FOREARM GIRTH IN INTERMEDIATE

SPORT ROCK CLIMBERS

Grace A. MacDonald

Bachelor of Science – Exercise Science East Stroudsburg University of Pennsylvania 2016

A thesis submitted in partial fulfillment of the requirements for the

Master of Science – Exercise Physiology

Department of Kinesiology and Nutrition Sciences School of Allied Health Sciences Division of Health Sciences The Graduate College

University of Nevada, Las Vegas May 2018 Thesis Approval

The Graduate College The University of Nevada, Las Vegas

April 12, 2018

This thesis prepared by

Grace A. MacDonald entitled

Handgrip Fatigue and Forearm Girth in Intermediate Sport Rock Climbers is approved in partial fulfillment of the requirements for the degree of

Master of Science – Exercise Physiology Department of Kinesiology and Nutrition Sciences

James Navalta, Ph.D. Kathryn Hausbeck Korgan, Ph.D. Examination Committee Chair Graduate College Interim Dean

Jack Young, Ph.D. Examination Committee Member

Brian Schilling, Ph.D. Examination Committee Member

Szu-Ping Lee, Ph.D. Graduate College Faculty Representative

Abstract

Handgrip fatigue and forearm girth in intermediate sport rock climbers Background: Rock climbing has been increasing in popularity both recreationally and competitively. Indoor sport rock climbing is a type of climbing where the climber ascends a wall using artificial rocks (hand and foot holds) and is attached to a safety rope. Despite this increase in popularity of the sport, the physiological responses to sport climbing as an exercise to specific muscle groups are not well defined in literature. Purpose: The purpose of this study was to quantify the change in handgrip strength over a 30-minute bout of continuous climbing, specifically in intermediate sport climbers. An additional aim of this study was to quantify any change in forearm girth over a bout of climbing and compare it to the change in strength and to identify if there is a relationship between the two. Methods: Ten intermediate rock climbers

[Age: 26.7±6.7 years; Height: 174.5±6.12 cm; Mass: 68.14±8.21 kg; Body Fat %: 15.75± .63 %;

Years Climbing: 7.3±4.69 years;] consented to participate and completed baseline handgrip strength (via handgrip dynamometer) and forearm girth (via tape measure) measurements. A climbing questionnaire indicated their rock climbing ability and defined them as intermediate climbers. Each participant ascended one of two 5.9 routes as many times as possible in 30 minutes. After each ascent, heart rate was taken via 15 second radial palpation and handgrip strength and forearm girth was measured. Data were analyzed using repeated measures ANOVA and correlation at the p < .05 level. Results: Dominant handgrip strength decreased by 22% and non-dominant handgrip strength decreased by 23%. Dominant and non-dominant forearm girth increased by 4.4%. The average heart rate reached while climbing was 71±4.2 % of age- predicted HRmax. Conclusion: Our results show that over a 30 minute bout of climbing, intermediate sport climbers’ handgrip strength decreases and forearm girth increases.

iii

Acknowledgments I would like to thank Southern Utah University (SUU) for collaborating with us and granting us permission to utilize their indoor rock climbing wall on campus. Additionally, I would like to thank Jacob Manning, M.S. of the Outdoor Recreations Department at SUU for designing and setting the two climbing routes used in this study. I would like to thank Dr. James Navalta, my advisory committee chair and academic advisor for his continual guidance and help throughout my graduate career and thesis project. I also would like to thank my advisory committee members, Dr. Brian Schilling, Dr. Jack Young, Dr. Szu-Ping Lee, PT, as well as my fellow graduate students in the Exercise Physiology Department. This project could not have been completed without everybody’s continual support and help.

Table of Contents Abstract ...... iii Acknowledgments ...... iv List of Figures ...... vi Chapter 1: Introduction ...... 1 Statement of Purpose ...... 3 Statement of Hypotheses ...... 3 Chapter 2: Literature Review ...... 4 Handgrip strength in sport climbing ...... 4 Oxygen consumption in sport climbing ...... 6 Chapter 3: Methods ...... 9 Participants ...... 9 Procedures ...... 9 Rock Climbing Protocol ...... 10 Data Analysis ...... 12 Chapter 4: Results...... 13 Participants ...... 13 Handgrip strength ...... 13 Forearm girth ...... 15 Forearm girth and handgrip strength correlation ...... 17 Heart Rate ...... 19 Rest Period ...... 19 Chapter 5: Discussion ...... 21 Appendix A ...... 27 IRB Permissions ...... 27 Appendix B ...... 28 SPSS Data ...... 28 References ...... 36 Curriculum Vitae ...... 38

List of Figures Figure 1: Retraced figure-8 safety knot…………………………………………………….…10 Figure 2: PETZL GriGri Belay Device………………………………………………………..10 Figure 3: Top-rope route 1: 5.9 (YDS)………………………………………………………..11 Figure 4: Top-rope route 2: 5.9 (YDS)…….………………………………………………….11 Figure 5: The change in handgrip strength for the dominant hand…………………………....14 Figure 6: The change in handgrip strength for the non-dominant hand………………………15 Figure 7: Change in dominant forearm girth………………………………………………….16 Figure 8: Change in non-dominant forearm girth……………………………………………..17 Figure 9: Correlation between dominant handgrip strength and forearm girth……………….18 Figure 10: Correlation between dominant handgrip strength and forearm girth……………...19 Figure 11: Average rest times in seconds over 30 minutes of climbing………………………20

Chapter 1: Introduction Rock climbing has increased in popularity recreationally and competitively since the Rock

Climbing World Cup in 19891. Competitively, there are sanctioned competitions all over the

United States for all types of rock climbing sponsored by USA Climbing, as well as overseas.

These types of climbing include sport climbing, speed climbing, and bouldering. Speed climbing is attempted on auto-belay, with the competitor clipped in to an automatic belaying device which automatically takes in rope slack as the climber ascends the wall. Competitors are ranked based on how long it takes them to climb a specific route, which is usually standardized. Bouldering is attempted without a climbing rope and with landing mats for protection. A number of individual, short routes or “problems,” are attempted and judged upon completion (USA Climbing). Indoor sport climbing is generally what is looked at in research. Sport (or lead) climbing is when climbers ascend a climbing wall and clip a safety rope through a succession of bolt anchors along the route. These routes are established by professional route-setters2,3. These competitions take place year-round, and now will make way for climbers to qualify for the 2020 Olympic Games, where rock climbing is going to be introduced for the first time as an Olympic Sport.

Aside from competitive rock climbing, it is increasing in popularity as a means for recreational physical fitness and exercise. It is estimated that every day 3,000 people try rock climbing for the first time4. According to the Climbing Business Journal, from 1986 to 2017, 682 new climbing gyms opened in the United States. More recently, from 2012 to 2017, an additional 312 indoor rock climbing facilities opened.

As one progresses in their career, just like in any sport, there are different levels of climbers.

According to the International Rock Climbing Research Association (IRCRA) lower grade climbers climb from 5.1-5.9 (YDS), intermediate females climb from 5.10a-5.11a, intermediate males climb from 5.10a-5.11c. In the United States, the Yosemite Decimal System (YDS) is used

to grade sport climbing routes. This system is from 5.1-5.15c. Beginning at 5.10, there are a, b, c, and d subcategories before the next numerical grade.

Previous studies in rock climbing have explored the physiological response of handgrip strength in elite climbers (5.12d-5.14a for males and 5.12d-5.14d), recreational (5.1-5.9), and non- climbers. As in any other sport, with practice and repetition one can surpass the recreational/beginner phase quite quickly. On the other end of that, one must train vigorously and for many years in order to reach the elite level. With that being said, most athletes in the climbing community can be identified as intermediate climbers.

Although rock climbing has increased in popularity in recent years, the physiological responses to climbing are not vastly studied relative to other sports2. It is important to understand physiological responses to any sport to succeed as an athlete or as a coach to properly train athletes for improvement and success. Rock climbing is a unique sport which requires great upper limb strength, more specifically in the fingers and forearms. Forearm strength is an important factor while climbing because the sport almost entirely involves sustained and intermittent isometric forearm muscle contractions5. Previous research has looked in to the importance of upper limb strength while climbing, specifically the fingers and forearms. In climbing, the force contact with most holds is generated by the effect of body mass along the gravitational line, as the external force pulls the hand onto the hold with muscular force maintaining the specific hand position against the external force6. However, the importance of this strength as it pertains to intermediate sport rock climbers has not been assessed. Previous research by Watts et al. has indicated that after climbing until fatigued, elite climbers’ handgrip strength decreases by 22%7.

Statement of Purpose

The purpose of this study was to quantify the change in handgrip strength over a 30-minute bout

of continuous climbing, specifically in intermediate sport climbers. An additional aim of this

study was to quantify any change in forearm girth over a bout of climbing and compare it to the

change in strength and to identify if there is a relationship between the two.

Statement of Hypotheses

It was hypothesized that handgrip strength would decrease over the duration of the 30-minute

bout of continuous climbing. H0= µpre = µpost; H1= µpre > µpost. It was also hypothesized that forearm girth would increase over the duration of the 30-minute bout of continuous climbing.

H0= µpre = µpost; H1= µpre < µpost. An additional hypothesis was that the two would have a strong negative correlation with one another.

3 Chapter 2: Literature Review Handgrip strength in sport climbing

Most research focuses heavily on the population of elite climbers and their handgrip response to climbing, as well as anthropometric measures. When assessing handgrip strength, it is important to know that the handgrip dynamometer does not perfectly replicate the grips used in climbing.

There are four main grips used while rock climbing- crimp, half-crimp, open handed and pinch1.

Of these four grips commonly used, the pinch is the most similar to the grip used when holding a handgrip dynamometer. Grant et al. investigated handgrip strength in 30 males (n=10 elite rock climbers, n=10 recreational rock climbers, n=10 non-climbers). The dynamometer was adjusted for each participant so that the second joint in the middle finger was at a 90° angle. Each participant was instructed to hold the dynamometer and grasp firmly for two seconds with their arm extended downwards away from the body8. Left hand grip strength scores were significantly higher in the elite group than the other two groups which suggests that grip strength is important for elite rock climbers8. Previous research by Watts et al. suggested that grip strength was not an important measurement in elite climbers because when compared to norms, male elite climbers scored in the 50th percentiles for their age range9. However, it is important to remember that this study collected baseline data at rest, not while climbing. While the dynamometer is commonly used to assess climbers’ grip strength, it has been compared with other climbing specific tests.

The results from one study analyzed the difference between these two types of tests and concluded that measuring grip strength via dynamometer is not specific in determining climbing ability in elite climbers, but can be used for lower level athletes. The specific test used in this study included ledge hangs and pull up holds for a duration of time, which assessed more advanced grips and activated more muscle groups used during climbing than just the simple

handgrip dynamometer test. The results from these climbing specific tests showed a greater correlation to climbing ability when compared to the results from the hand grip dynamometer10.

Watts et al. looked at acute changes in handgrip strength, endurance, and blood lactate in sustained sport rock climbing. The purpose of this study was to look at hand-to-rock contact strength as it is an important factor for success while climbing7. Expert climbers (n=11) climbed continuously on a 5.12 route which was near the limit of each subject’s on-sight lead climbing ability. On-sight refers to a route that one can ascend without a preview or fall11. Handgrip strength was measured on each hand and averaged pre-climb, post-climb, and at 5, 10, and 20 minutes during recovery. Additionally, handgrip endurance (the time that the dominant hand handgrip force could be sustained at 70% of handgrip strength) was taken pre-climb, post-climb, and at 20 minutes during recovery. The participants climbed the route continuously until they fell. From pre-climb to post-climb, handgrip strength decreased by 22% and handgrip endurance decreased by 57%. Both measures remained depressed after 20 minutes of recovery. The results of this study showed that the measurement of handgrip endurance was impacted more than handgrip strength when continuously climbing a difficult route7. This is an interesting finding because climbers tend to attribute climbing failure to the decrease in grip strength they experience, however these results show that climbers actually experience a loss in grip endurance. This study also was found that a decrease in handgrip strength significantly correlated with an increase in blood lactate levels, indicating that while intensity and exertion was increasing, handgrip strength was decreasing. This study succeeded in defining acute changes in handgrip strength and endurance after sustained climbing, however the mechanisms of fatigue were not explored7. As mentioned before, it has been argued that measuring handgrip strength is not necessarily the best measure for rock climbers because of its lack in specificity. However,

5 handgrip strength continues to be looked at because climbers attribute failure to “grip fatigue”3.

Watts et al. looked further into specific handgrip strength by recording forearm electromyogram

(EMG) responses for six handgrips during climbing and compared these responses to a maximum handgrip test6. Five experienced climbers (mean climbing difficulty 5.11b) performed

4 moves up and down with a crimp, pinch, three 2-finger combinations, and an open-hand grip6.

They concluded that all climbing EMGs exceeded handgrip EMGs which shows that handgrip dynamometry lacks specificity in actual rock climbing at the experienced level6. Watts et al. concluded that although maximum handgrip strength is often correlated with climbing ability, elite climbers’ values are not usually high when compared with age/sex norms. Therefore, it is unclear whether a decrease in handgrip strength is a direct cause of falls in climbing, despite climbers reporting falling due to “grip fatigue”6. Watts et al. successfully examined physiological variables relating to elite sport climbing, however there are still more questions to be answered.

This study is one of the only ones to explore the physiological responses that result after climbing. Overall, handgrip dynamometry lacks specificity in elite climbers, however this has not been determined for lower level climbers.

Oxygen consumption in sport climbing

A common strategy in exercise science used to determine fitness capacity is measuring maximal oxygen consumption. Most often, maximal oxygen consumption tests take place on the treadmill, however other modes such as cycle ergometer and upper body ergometer can also be used.

Merimer et al. explored the relationship between heart rate (HR) and oxygen consumption (VO2) over three progressively difficult climbing routes. HR increased progressively, however VO2 remained the same over the three trials. This differs from the typical linear HR-VO2 relationship during other exercise modes such as the treadmill and cycle12. The results from this study suggest

that VO2 has a small role in determining climbing performance13. Another study by Booth et al. instructed elite climbers to perform an incremental climbing test to volitional fatigue on a vertical climbing ergometer to reach a VO2climb-peak11. This was then compared to the oxygen uptake during an outdoor climbing bout. The percentage of VO2climb-peak required during an outdoor route is substantial which is evidence that the aerobic system is being used during climbing, despite previous data which suggests a non-linear HR and VO2 relationship11. In addition to the relationship between HR and VO2, HR and rate of perceived of exertion (RPE) have been compared between beginner and recreational indoor climbers14. In this study, beginner and recreational sport climbers climbed two routes that varied in difficulty from 5.6 to 5.8. HR was recorded pre-climb, during climbing and during recovery. There was a 20-minute rest period between each climb, and RPE was recorded after each climb14. The main conclusions of this study were that changes in HR and RPE differ between beginner and recreational climbers. It was noted that these findings may be beneficial to climbing instructors because it shows how climbers with varied skill levels respond during climbing14. Billat et al. investigated aerobic capacity in four elite climbers by having them perform a VO2 max test on the treadmill, and a pulling test, and then a climbing test and compared the three.5

It was concluded that the VO2 demands of climbing are low5. These studies assess the energy systems used while climbing, however do not define the major muscle groups used. It has been defined that climbing is predominately a series of isometric muscle contractions, however literature shows most studies exploring HR and VO2 relationship, handgrip strength and endurance in elite climbers, or simply defining anthropometrics. Additionally, many of these studies do not asses the discussed parameters after a bout of climbing. Studies assessing anthropometrics have concluded that it is important to consider body mass when measuring

7 muscular strength in climbers1. Giles et al. found that when absolute strength was measured, there was little difference between climbers and non-climbers. However, when strength was measured relative to body mass, climbers’ strength was significantly higher1.

Another group of expert climbers (having the ability to lead 5.12b) was assessed to evaluate the effects of an active vs. a passive recovery on post-climbing blood lactate and handgrip strength3.

The handgrip strength of these expert climbers was measured pre-climb, and at 1, 10, 20, and 30 minutes post-climb. Handgrip strength was significantly decreased at one minute post-climb for the active recovery group (cycling at 25 watts) and was not significantly changed for the passive recovery group. Both group’s handgrip strength returned to pre-climb level by 20 minutes post- climb. Their climbing protocol was to ascend a 5.12b route which was relatively sustained in difficulty throughout its 20 meters in length3.

To our knowledge, there have not been any studies assessing the change in forearm girth in sport rock climbers as it relates to grip strength.

Chapter 3: Methods Participants

A total of 10 subjects (7 males, 3 females) were recruited via announcements made in outdoor recreation classes to individuals who are affiliated with Southern Utah University (SUU). At the start of the visit, all participants completed a health risk questionnaire and a climbing history questionnaire which assessed climbing history and current climbing ability. Participants were informed of the purpose, protocol and risks and associated with the study before providing written, informed consent. Those classified as “moderate risk” or had an implantable device

(such as a Pacemaker), or had orthopedic, cardiovascular, respiratory, or metabolic conditions; less than one year of climbing experience, less than a 5.9 (YDS) top rope on sight climbing ability, any upper limb injuries were excluded from the study. This study was approved by the

University of Nevada, Las Vegas Biomedical Research Integrity for Human Subjects Board-

[1164228-4] Handgrip fatigue and forearm girth in intermediate sport rock climbers.

Procedures

Participants were to report to the indoor climbing wall for testing on one occasion. At the beginning of their visit, participants were presented the informed consent document which they were instructed to read over and ask any questions before signing. Once this was signed, the participants completed anthropometric measures of height (self-reported), weight and estimation of body fat % via Tanita TBF-521 Bioelectrical Impedance. Participants were then assessed for baseline handgrip strength via Takei 5001 Hand Dynamometer, and baseline forearm girth via tape measure around the widest part of the participants’ forearm. Baseline handgrip strength was measured with three trials on each hand, by the participant squeezing the dynamometer at maximal effort for ~3 seconds. The highest value out of the three trials was recorded as baseline.

Subjects then filled out a short questionnaire addressing climbing history, experience, and current climbing ability/training status.

Rock Climbing Protocol

After anthropometric measurements were completed, the climbers were instructed to put on their climbing gear (rock climbing shoes and harness) and tie in to the top rope with a retraced figure-

8 knot, while the belay device. The participants were then reminded of the protocol: to ascend one of the two 5.9 route on top rope as many times as possible over 30 minutes, with heart rate, handgrip strength, and forearm girth being measured at the completion of each ascent. Two identical 5.9 routes were set on the same face of the climbing wall using the same hold types in order to assure the routes were alike. Climbers were instructed to stay on route (using only one color for both hands and feet) and climb continuously from start to finish, with breaks only at the bottom (after being lowered) as needed. These rest times were recorded by members on the research team. Climbers were able to use features on the wall, as well as the arête along with the designated climbing holds.

Figure 1: retraced figure-8 safety knot Figure 2: PETZL GriGri Belay Device 10

Figure 3: Top-rope route 1: 5.9 (YDS) Figure 4: Top-rope route 2: 5.9 (YDS)

Heart rate was taken by palpating the radial artery for 15 seconds then multiplying by 4 to determine beats per minute (bpm). Handgrip strength was assessed as the participant squeezed the dynamometer once (each hand) using maximal effort. Forearm girth was measured at the widest part of the participants’ forearm and recorded in centimeters. Participants also were reminded that the test can be terminated at any time if needed. The data was coded in terms of subject numbers that were assigned to participants. Participants were able to view their data after their test if they wanted.

Data Analysis

Data are presented as mean±SE. IBM SPSS Statistics 23 Software (Armonk, New York) and

Microsoft Excel 2016 were used to analyze results. A repeated measures ANOVA was used to compare the means of the changes in handgrip strength and forearm circumference over the 30- minute bout of climbing for dominant and non-dominant hands. A correlation for change in handgrip strength and forearm circumference for the first 50% of the climb was also determined for dominant and non-dominant hands. Additionally, t-tests were used to compare the change in handgrip strength between dominant and non-dominant hands. P <. 05 was used to indicate significance.

Chapter 4: Results Participants

The 10 recruited participants completed the study [Age: 26.7±6.7 years; Height: 174.5±6.12 cm;

Mass: 68.14±8.21 kg; Bodyfat %: 15.75±7.63 %; Years climbing: 7.3±4.69 years; Typical range of grades climbed: 5.7-5.12 (YDS)]. It was determined that the participants climbed intermediate difficulty (5.9-5.10d) most often. All participants were able to climb a minimum of four complete ascents, with a mean of 15.8±5.8 ascents of either route over the 30 minutes. Intensity of the two routes was matched by heartrate. An independent t-test was used to determine if the intensities of the route were significantly different (t8 = -1.863, p = .100), and there was not a significant difference between the two routes: (yellow route: 73% age-predicted HRmax; white route: 69% age-predicted HRmax).

Handgrip strength

The change in handgrip strength and forearm girth were assessed for all participants in the study.

Due to the fact that all participants completed a different number of ascents, change in handgrip strength and forearm girth was assessed in quadrants of individual participants’ climbs: the first

25% of the 30 minute bout, 50%, 75%, and 100%. All data presented are normal (see appendix).

Dominant: A repeated measures ANOVA was used to compare means for the quartiles.

Mauchly’s test of sphericity was significant, and Huynh-Feldt and post-hoc tests were used to (F

= 15.958, p < .001 ). Dominant handgrip strength decreased by 22.1% over the duration of the climbing bout. During the first quarter of the climbing bout, handgrip strength decreased by

11.8%. Halfway through the climbing bout, handgrip strength decreased by 17.5%, and 75% through the climbing bout handgrip strength decreased by 19.7%. There was a significant decrease in handgrip strength from the pre-climb to all quartiles (p = .009; p < .001; p = .004; p =

.009) respectively. A dependent t-test was conducted to determine if there was a significant difference between pre- and post- dominant handgrip strength (t=8.463, p < .001).

a a

Figure 5: The change in handgrip strength for the dominant hand a: significant from pre-climb

Non-dominant: A repeated measures ANOVA was used to compare means for the quartiles.

Mauchly’s test of sphericity was significant, and Huynh-Feldt and post-hoc tests were used to (F

= 16.580, p < .001 ). Non-dominant handgrip strength decreased by 23% over the duration of the climbing bout. During the first quarter of the climbing bout, handgrip strength decreased by

10.5%. Halfway through the climbing bout handgrip strength decreased by 14.3% and 75% through the climbing bout handgrip strength decreased 18.5%. There was a significant decrease in handgrip strength from pre-climb to each quartile (p = .034; p = 002; p < .001; p = .002) respectively.

a a a

Figure 6: The change in handgrip strength for the non-dominant hand a: significant from pre-climb

A dependent t-test was conducted to determine if there was a significant difference between pre- and post- non-dominant handgrip strength (t=10.708, p < .001).

Forearm girth

Dominant: A repeated measures ANOVA was used to compare means for the quartiles.

Sphericity was assumed (F = 22.235, p < .001). Dominant forearm girth increased from pre to post by 4.5% (p < .001), and all increases were significant from pre (p = .002; p < .001; p = .001) for 25%, 50%, 75%.

a a a a

Figure 7: Change in dominant forearm girth. a: significant from pre-climb

Non-dominant: Non-dominant forearm girth increased from pre to post by 4.4% (p = .001), and from pre to each quartile thereafter (p < .01; p < .01; p < .01). Additionally, from 25% of the climb to 50% of the climb, forearm girth increased by 1.7% (p = .034), and from 25% of the climb to 75% of the climb forearm girth increased by 1.9% (p = .038).

ab ab a

Figure 8: Change in non-dominant forearm girth

a: significant from pre-climb; ab: significant from 25%

Forearm girth and handgrip strength correlation

Dominant: Additionally, participants’ forearm girth was correlated with handgrip strength.

These correlations represent the first 50% of the climbing bout. When the entire data set was looked at there was a weak correlation (r = -.311, p < .01); 25%: (r = -.265, p = .098); 75: (r = -

.246, p = .007). However, in both handgrip and girth, there were no significant increases or decreases after 50% of the climb. Therefore, only the first 50% of the data points for each participant were included in the correlation. There was a significant negative correlation (r = -

.392, p < .001).

Figure 9: Correlation between dominant handgrip strength and forearm girth

Non-dominant: When the entire data set was looked at there was a weak correlation (r = -.491, p

< .01); 25%: (r = -.335, p = .034); 75%: (r = -.416, p < .01). There was a significant negative correlation for non-dominant handgrip strength and non-dominant forearm girth for the first 50% of the climbing bout (r = -.400, p < .001).

Figure 10: Correlation between dominant handgrip strength and forearm girth

Heart Rate

Participants’ average heart rate (HR) while climbing was 71±4.2 % of age-predicted HRmax.

This demonstrates that although participants climbed various amounts of the same route, their intensity was about the same according to mean percentage of HRmax while climbing.

Rest Period

Rest periods in between each climb were measured for all participants. The rest times are measured in seconds. The mean rest time in between climbing intervals was 1:18±3.3 sec. The longest amount of rest time occurred 75% through the climb, where the mean is 1:22±33. This is towards the end of the 30 minutes, where subjects’ handgrip strength decreased as well (19.7% for the dominant hand and 18.5% for the non-dominant hand). However, it appears that participants took less rest time at the very end of their bout, perhaps to get more ascents in. This

is evidence that although participants’ handgrip strength decreased, they were still able to climb with less rest time. The last quarter of the climb rest time was 1:15±30 (p < .05).

Figure 11: Average rest times in seconds over 30 minutes of climbing

Chapter 5: Discussion The purpose of this study was to better understand the physiological demands of indoor sport rock climbing, specifically the occurrence of forearm muscle fatigue and change in forearm girth in intermediate climbers. Our hypothesis for the current study was that handgrip strength would decrease over the bout of climbing, and forearm girth would increase. We rejected the null hypothesis and accepted the alternate hypotheses: H1= µHGpre > µHGpost; H1= µGirthpre < µGirthpost.

The results of our study showed a significant decrease in dominant handgrip strength by 22.1%

(p < .05), and a significant decrease in non-dominant handgrip strength by 23% (p < .05), as well as a significant increase in dominant forearm girth by 4.5% (p < .05), and a significant increase in non-dominant forearm girth by 4.4% (p < .05). Additionally, there was a significant negative correlation for both dominant and non-dominant handgrip strength and forearm girth (p < .001).

Rock climbing almost entirely involves sustained and intermittent isometric forearm muscle contractions5. Muscle fatigue is a common complaint in physical activity (including rock climbing) and it can be defined as exercise-induced decrease in the ability to produce force15.

The results of our study show a 22.1% decrease in handgrip strength in the dominant hand, and a

23% decrease in handgrip strength in the non-dominant hand. Our results are similar to the results where elite climbers’ handgrip strength decreased by 22% when climbing to failure7. The participants in the previously mentioned study were instructed to climb continuously on an indoor sport climbing route (5.12a) until a fall occurred. This route involved a 7.4m vertical section, an 18.5m overhanging arch, and a 7.4m vertical down-climb where participants had to climb up, under the arch, and down without touching the floor and then reverse back up.

Participants were lead climbing, which is a more difficult type of climbing than top-rope where climbers clip their rope in to anchors along the route as one ascends. Handgrip strength was

measured 20 minutes before climbing, one minute after climbing, and five, 10, and 20 minutes post-climb. These participants were considered elite climbers. There has not been previous research on handgrip strength over a bout of climbing in intermediate climbers. The results from our study showed that handgrip fatigue progressively decreases in both the dominant and non- dominant hand while climbing. We found that in the dominant hand, handgrip decreased by

11.7%, 17.5%, 19.7%, and 22.1% during 25% of the climb, 50%, 75%, and 100% of the climb respectively. We found that in the non-dominant hand, handgrip decreased by 10.4%, 14.3%,

18.5%, and 23% during 25% of the climb, 50%, 75%, and 100% of the climb respectively.

It is common for climbers to attribute failure and/or the need for longer rest times to forearm/grip fatigue also known as the “pump”. This “pump” is an occurrence when the sensation of forearm tightness occurs and can cause one’s climbing ability to decrease. Although this occurrence is talked about a lot in climbing, it has yet to be studied. To our knowledge, no study has looked at change in forearm girth over a bout of climbing. However, there has been observations that fatigue in climbing occurs with an increase in forearm girth and pain16. Although forearm girth has not been measured, lactate has been used as a measure of fatigue in the peripheral muscles, mainly the forearms and upper body11. There was a previous study which looked at the effects of passive versus active recovery on lactate, and it was found that due to the increase in heart rate during active recovery, blood flow increases to the working muscles and is believed to enhance the removal of lactic acid17. The mechanism behind forearm girth increasing during rock climbing can be attributed to the repeated isometric contractions of the forearm which results in a stop in blood flow and increased swelling of the forearm. As one contracts the same muscles and repetitively keeps them contracted, strength output decreases as swelling and pain increases. The

participants in our study did not have much of a recovery period in between climbs, and the period that was spent recovering was passive. This passive recovery period could contribute to the decrease in blood flow to the working muscles of the upper body and forearms. In addition to active recovery enhancing blood flow in the peripheral muscles in climbers, cold water immersion has been found to be an effective recovery mode. Cold water immersion is a technique that is believed to induce localized vasoconstriction which reduces acute inflammation in the forearms18. Previously, vascular characteristics of rock climbers have been compared to untrained individuals, where brachial artery diameter and blood flow were measured19. It was hypothesized that rock climbers would show enlarged artery diameter and enhanced capillary filtration and capillary density20. In climbers, resting arterial diameter was 11.8% greater than in non-climbers, and capillary filtration capacity was 27.4% greater in climbers than non-climbers.

These results demonstrate that rock climbers have increased vasculature which provides information that repeated isometric ischemic conditions enhance vascular adaptations19. The results of our study show a 4.5% increase in forearm girth in the dominant hand and a 4.4% increase in forearm girth in the non-dominant hand. Additionally, the results of our study show a significant negative correlation between handgrip strength and forearm girth (dominant and non- dominant), which tells us that as handgrip strength decreases, forearm girth decreases. To our surprise, the correlation between handgrip strength and forearm girth was not strong in all 10 participants. However, perhaps this can be attributed to the fact that trained climbers have enhanced vascular adaptations, so their change in forearm girth over the bout of climbing was not substantial. It would be interesting to perform a similar protocol on un-trained climbers and assess their change in forearm girth.

Along with forearm muscle fatigue, rock climbing causes cardiovascular stress while climbing.

Heart rate during climbing was assessed to quantify the intensity of this physiological stress. The mean heart rate achieved over the 30-minute bout was 71±4.2% of age-predicted HRmax.

Previous research measuring heart rate for beginner and recreational climbers ranged from 76-

90% and 71-79% respectively14. According to this data, it is clear that beginners’ heart rate is higher while climbing than more experienced climbers’. Previous research also shows that experienced climbers have lower energy expenditure while climbing than beginners12. This suggests that skill and technique play an important role in energy expenditure while climbing, and this could influence heart rate14. The HR data recorded in our study is similar to that of previous studies14,1,13,12.

Rest time in between climbing bouts is not extensively researched. A study assessed the effects of active versus passive recovery on post-climbing blood lactate and handgrip strength3.

Although there are no recovery mode guidelines, passive recovery during and after climbing is assumed to be more common than active recovery. The results of the study by Watts et al. regarding active versus passive recovery and its effects on handgrip could not be compared because the passive recovery group did not experience a significant decrease in handgrip strength from the climbing bout3. The authors concluded that active recovery produced blood lactate levels equal to baseline level within 20-minutes post-climb. However, these rest times were not assessed in between multiple ascents as they were in our study. A systematic review looking at optimal rest time during resistance training show that 2-5 minute interest rest intervals may produce the greatest power-strength benefits, however rest interval length may vary based on athlete’s training age, fiber type, and genetics21. The results from our study show a mean rest

time in between climbing intervals to be 1:18±3.3 sec. This rest time barely falls in to the recommended rest time of 2-5 minutes. It is possible that with longer rest times, handgrip strength would not decrease as substantially.

This study assessed the change in handgrip strength and forearm girth in intermediate climbers over a 30-minute bout of climbing. A limitation in this study is that we could have assured all participants climbed for 30-minutes, instead of including both climb time and rest time during the 30-minute bout. Ensuring that participants climbed for 30-minutes total could possibly provide more substantial changes in forearm girth and how it correlates to handgrip strength.

Also, pre-climb nutrition was not controlled for. Additionally, we measured forearm girth at the widest part of each individual’s forearm, however measuring girth more centrally could better explain the forearm “pump” that occurs while climbing. The tightness sensation occurs in the medial/distal area of the forearm, rather than the widest part, which is more towards the elbow.

Future studies should regulate climbing time, measure forearm girth distally, or look at blood flow via ultrasound and/or water displacement to better explain the “pump” sensation that occurs while climbing.

In summary, the results of our study showed that in intermediate sport rock climbers, both dominant and non-dominant handgrip strength significantly decreased by 22.1% and 23% respectively over a 30-minute bout of climbing. Additionally, forearm girth increased significantly by 4.5% and 4.4% in the dominant and non-dominant hand respectively. The heart rate response showed that intermediate climbers ascending a 5.9 route multiple times resulted in

71 ± 4.22 % of age-predicted HRmax. The rest times in between ascents showed a mean of 1:22 ±

33 sec, which is less than the recommended rest time for resistance training of 2-5 minutes. It is possible that with longer rest times, handgrip strength would not decreases as substantially.

Our results can contribute to the existing literature and help us to better understand the physiological demands of indoor sport rock climbing, specifically the change in handgrip strength and forearm girth while climbing. As a result of better understanding this common muscle fatigue, indoor rock climbing facilities and/or rock climbing instructors can better prescribe recommendations for time of climbing bouts and rest time which will maximize time spent on the wall. These results present valuable information than will have a big impact on the climbing community, specifically the population which makes up most of it.

Appendix A IRB Permissions

Appendix B SPSS Data

Dominant handgrip ANOVA

Non-dominant handgrip ANOVA

Dominant girth ANOVA

Non-dominant girth ANOVA

Dominant HG and Girth Correlation- entire data set

Non-Dominant HG and Girth Correlation- entire data set

Dominant HG and Girth Correlation- first 25%

Non- Dominant HG and Girth Correlation- first 25%

Dominant HG and Girth Correlation- first 50%

Non-Dominant HG and Girth Correlation- first 50%

Dominant HG and Girth Correlation- first 75%

Non-Dominant HG and Girth Correlation- first 75%

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Curriculum Vitae Grace A. MacDonald [email protected] EDUCATION M.S. Exercise Physiology In progress University of Nevada Las Vegas, Las Vegas, NV Mentors: James Navalta, Ph. D; Jessica R. Knurick, Ph. D, RD

B.S Exercise Science 2016 East Stroudsburg University of Pennsylvania, East Stroudsburg, PA Concentration: Sport and Exercise Conditioning TEACHING EXPERIENCE Teaching Assistant, Kinesiology and Nutrition Sciences, University of Nevada Las Vegas 2017-2018 Exercise Physiology Lab (KIN 491) Instructed students through basic exercise physiology lab testing, data collection, and analysis RESEARCH EXPERIENCE Undergraduate Student Mentor 2017-2018 Role: To conduct and assist nutrition undergraduates in the exercise physiology lab

Utilization of Waist Circumference to Determine Type 2 Diabetes Risk among Normal and Overweight Individuals Purpose: To identify if waist circumference can be a better predictor than BMI when determining if one is a prediabetic or diabetic individual

Effects of Intermittent Fasting on Fat Oxidation during Submaximal Exercise Purpose: To identify whether dietary patterns with intermittent fasting reliably alter RER at varying submaximal exercise intensities

Graduate Research Assistant 2016-2017 Role: To conduct and assist with nutrition science research under the Supervision of Dr. Jessica Knurick

Effects of Postmeal Walking on 24-hour Glucose Control Purpose: to evaluate the effects of walking on postmeal glucose control in an acute time period (2 hours) and assess the prolonged impact of a single bout of postmeal walking on 24-hour glucose control in prediabetic individuals.

ABSTRACT PRESENTATIONS Poster Presentations

Esdaile, H., Schilling, B.K., MacDonald, G.A., Knurick, J. Utilization of Waist Circumference to Determine Type 2 Diabetes Risk Among Normal and Overweight Individuals. Nevada INBRE Student Award, University of Nevada Las Vegas, Fall 2017.

Calvano, A.R., MacDonald, G.A., Schilling, B.K., Knurick, J., Esdaile, H. Effects of Intermittent Fasting on Fat Oxidation During Submaximal Exercise. Nevada INBRE Student Award, University of Nevada Las Vegas, Fall 2017.

MacDonald, G.A., Montes, J., Tanner, E.A., Bodell, N.G., Manning, J.W., Navalta, J.W. A Mile Trail Run can Predict Performance for a 5K Trail Race. Annual Meeting of the Southwest American College of Sports Medicine, Costa Mesa, CA, 2016; Annual National Meeting of the American College of Sports Medicine, Denver, CO, 2017.

Aguilar, C.D., Woita, A.C., Montes, J., Bodell, N.G., Tanner, E.A., MacDonald, G.A., Thomas, C., Manning, J.W., Taylor, J., Navalta, J.W. Prediction of Mechanical Efficiency from Body Fat Percentage and Years of Experience in Male and Female Rock Climbers. Annual Meeting of the Southwest American College of Sports Medicine, Costa Mesa, CA, 2016.

Bodell, N.G., Tanner, E., Montes, J., MacDonald, G.A., Thomas, C., Manning, J.W., Taylor, J.E., Navalta, J.W. Excess Post-exercise Oxygen Consumption Following Bouts of Moderate and Vigorous Climbing. Annual Meeting of the Southwest American College of Sports Medicine, Costa Mesa, CA, 2016.

Tallent, R.C., Woita, A.C., Aguilar, C.D., Young, J., Navalta, J.W., Bodell, N.G., Montes, J., Tanner, E.A., MacDonald, G.A., Thomas, C., Manning, J.W., Taylor, J. Comparison of Mechanical Efficiencies from Steady State and Rapid Speed Rock Climbs. Annual Meeting of the Southwest American College of Sports Medicine, Costa Mesa, CA, 2016.

Woita, A.C., Young, J., Navalta, J.W., Bodell, N.G., Montes, J., Tanner, E.A., MacDonald, G.A., Thomas, C., Manning, J.W., Taylor, J. Mechanical Efficiency during Repeated Attempts of Indoor Rock Climbing. Annual Meeting of the Southwest American College of Sports Medicine, Costa Mesa, CA, 2016. GRANTS AND PROPOSALS Funding Source: University of Nevada Las Vegas, Exercise Physiology Title: Travel Grant to Deliver Poster Presentation to Southwest American College of Sports Medicine Conference, Orange County, October, 2016. Amount: $100.00 Funded

Funding Source: American College of Sports Medicine Title: The 2017 Steven M. Horvath Travel Award which provides funds travel expenses for underrepresented minority graduate students traveling to the ACSM Annual Meeting to present their scholarly work. Amount: $500

Funding Source: American College of Sports Medicine Title: The 2017 Michael L. Pollock Memorial Fund; established to help pay travel expenses for graduate students traveling to the ACSM Annual Meeting to present their scholarly work. Amount: $200

Funding Source: Graduate and Professional Student Association Title: Travel Grant to Deliver Poster Presentation to the National American College of Sports Medicine Conference, Denver, Colorado, June 2017 Amount: $500 Funded SERVICE Community Service

Volunteer at Cathedral Kitchen, Camden, NJ Role: prepared and served meals on Thanksgiving morning to the less fortunate 2010-2015

University Service

Student Representative: Professionals in Nutrition for Exercise and Spots (PINES) 2016-2017 AWARDS & HONORS

Student Representative, Professionals in Nutrition for Exercise and Sports 2016-2017 Pennsylvania State Athletic Conference Scholar-Athlete Award 2012-13, 2013-14, 2015-16 Excellence in Exercise Science Award, Top 10 in Class 2016 Member of The National Society of Leadership and Success 2016 PROFESSIONAL CERIFICATIONS

CITI: Biomedical Research Investigator 2016-present CPR & First Aid 2014-present