SPS2201 Exercise Physiology

Athlete 1

SPS2201 – Exercise Physiology Laboratory Report 5 Establishing aerobic capacity and anaerobic threshold of a sub-elite hockey player using an increasing exercise test on a treadmill

Greg Levin Student Number: 2011360

Edith Cowan University Athlete 2

Introduction

When exercising in a competitive environment it is a distinct advantage for athletes to be able to possess any information that will assist them in improving their performance. Certain key variables such as heart rate (Wilmore & Costill, 1999), VO2 max (McArdle, Katch, & Katch, 1994), and blood lactete (Billat, 1996) can all be used to measure levels of performance. Once these figures are known a training programme can be set up to improve each and thus improve overall performance.

Wilmore and Costill (1999) define heart rate as “the amount of work that the heart must do to meet the demands of the body.” Heart rates increase as the exercise intensity increases and can reach a predicted maximum of 220 beats per minute minus the athlete’s age (Pfitzinger & Freedson, 1998).

Maximal oxygen uptake, also more commonly known as VO2 max, is “the maximal capacity for oxygen consumption by the body during maximal exertion” (Wilmore & Costill, 1999, p. 697). The concept is also discussed by McArdle, Katch and Katch (1994) who explain that VO2 max occurs when despite increasing or continuing workloads the amount of oxygen inhaled does not increase. VO2 max can be measured either as an absolute figure or as a relative figure. There are two different ways of expressing VO2 max. They are the absolute VO2 max, expressed in litres per minute (L/min) and the relative VO2 max expressed in millilitres per kilogram per minute (ml/kg/min) (Wilmore & Costill, p. 141).

Lactate threshold is defined by Wilmore and Costill (2002, p. 136) as “the point at which blood lactate begins to accumulate above resting levels.” Lactic acid is present in the body even at rest (Billat, 1996) but increases during heavy exercise (Loat & Rhodes, 1993). When there is an overload of lactic acid in the blood the point of threshold is reached. Gupta, Goswami, Sadhukhan, and Mathur (1996) mention that the lactate overload is a contributory factor in muscle fatigue. Therefore the lactate threshold is the point at which an athlete can exercise at maximal levels for long durations (Loat & Rhodes, 1993) a point also referred to as the functional aerobic capacity. Athlete 3

The knowledge of when all these factors occur is important in training and competition to achieve maximal results.

To assess the aerobic capacity of the athlete by measuring their VO2 max, blood lactate and heart rate.

Methods

Participants

One participant completed the test. The participant was approached and offered the opportunity to undertake the test, in order to acquire knowledge about her level of fitness and to assess her aerobic performance. The participant was a sub-elite hockey player participating in training twice a week and playing 1 match per week. This added up to 3 hours of training per week. She was 18 years of age, 168cm tall, weighed 53 kilograms and had age predicted heart rate max of 202 (220 less age). Participation in the test was voluntary and the subject could request to end the test at any time.

Materials

The equipment that was required to carry out the test included a treadmill, a polar heart rate monitor and IBM interface, an Acccusport lactate analyser and lactate test strips, sterile disposable gloves, medi-swabs and dry swabs, tissues, plasters, a biological hazard bag, a RPE board, a medgraphics gas analyser and Breeze ex software, a two-way valve mouthpiece, nose clips, and a pneumotach.

Procedure

The subject was informed about the testing procedure. Her personal details were entered onto the computer and she was fitted with a heart rate monitor. A resting heart rate as well as a resting blood lactate concentration was recorded. The subject was then instructed to warm up for a period of two minutes. After this time the subject Athlete 4 got off the treadmill and stretched. Her heart rate and blood lactate were recorded. After approximately 30 seconds the testing procedure recommenced. The subject inserted the gas analyser into her mouth and the nose clips were placed over her nostrils. Gas recordings were taken by the gas analyser every 15 seconds. At the end of every two minutes heart rate, blood lactate and RPE were recorded. The subject requested that the test was stopped at the completion of her fourth workload, including warm-up. After the completion of the test a final warm down period took place. The subject continued running on the treadmill but at a reduced workload. Again following these 2 minutes heart rate and lactate were recorded.

Table 1 Subjects test protocol

Time Speed Incline 0 - 2 Minutes 3.5 1 2 - 4 Minutes 6 1.5 4 - 6 Minutes 7 2 6 - 8 Minutes 8 3 Cool Down 3 0

Results

As the workloads increased, there was a general tendency for measurable variables to increase too. Lactate, however, remained relatively stable until reaching threshold. Thereafter it increased substantially reaching a maximum of 12.5mmol/L at the end of warm down period (see figure 1). RPE increased consistently and contrary to expectations, as seen in figure 1, there was no correlation with lactate concentration. VO2 continued to increase throughout the test and there was no leveling off visible (see figure 2). This suggests that VO2 max was not reached but most likely it was very close and had the testing continued longer a maximum value would been attained. The heart rate climbed steadily throughout except for a slight drop in the last workload. The initial heart rate was 80bpm and a maximum rate of Athlete 5

181 beats per minute was recorded, again this value is not far off from the predicted

-1 heart rate max. The maximum VO2 recorded was 2597.5ml.min .

As expected heart rate decreased during recovery, but lactate continued to increase.

Lactate RPE )

L 15 20 / l o

15 R m

10 P E m (

10 e t

a 5 t 5 c a

L 0 0 0 1 2 3 4 5 6 Workload Stage

Figure 1. Lactate and RPE at increasing levels of exercise intensity

Heart Rate VO2

) 200 2750 V m 180 p 2500 O b 2 ( 160

( e 2250 m t 140 a l /

R 120 2000 m

t r 100 i n a 1750 ) e 80 H 60 1500 0 1 2 3 4 5 6 Workload Stage

Figure 2. VO2 and heart rate at increasing levels of exercise intensity Athlete 6

Discussion

Wilmore and Costill (1999, p. 693) define anaerobic threshold as “the point at which the metabolic demands of exercise can no longer be met by available aerobic sources and at which an increase in anaerobic metabolism occurs.” Anaerobic threshold is at most times thought to coincide with the onset of blood lactate accumulation (Schneider & Pollack, 1991) or lactate threshold.

In this test the lactate threshold was determined by the individual anaerobic threshold (IAT), this is a test that involves taking lactate measurements during both exercise and recovery phases (Loat and Rhodes, 1993). The IAT is a newer theory that opposes the older theory of a standard blood lactate concentration to signify threshold; a threshold value of 4mmol/L was defined as the standard lactate value (Loat & Rhodes, 1993).

There are many factors with can influence the lactate measurements such as carbohydrate and caffeine consumption, hydration status as well as environmental conditions (Pfitzinger & Freedson, 1998). These factors were not controlled during testing.

Gupta et al. (1996) reported that the highest lactate concentration occurred 3 minutes after the exercise. Therefore in this test values were consistent with previous studies. Fukaba, Walsh, Morton, Cameron, Kenny, and Banister (1999) mention that lactate concentration continues to increase after exercise because of the build up in previously active muscles. However Gupta et al. also reported that there was a decrease after 5 minutes (a further 2 minutes after maximal levels).

McArdle, Katch and Katch (1994, p. 64) explain how ATP is supplied to the cells, using oxygen that is taken in during aerobic metabolism. The ATP provides energy for the muscles to function. VO2 max is the maximum amount of oxygen taken in and therefore provides maximal oxygen for the utilisation of energy production. Athlete 7

VO2 max was not reached, but it was approaching as can be seen by the shape of the curve in figure 2. The fact that heart rate reached 90% of the predicted max also suggest that VO2 max was not too far off as these two in most cases occur together.

The reason that VO2 is measured in two different ways is because of the different information these measures provide. Hutchinson, Cureton, and Outz (1991) mention that if there is little variation between the relative VO2 max of athletes then these it can be assumed that these athletes are in similar physical condition. Relative

VO2 accounts for size difference in athletes by measuring their absolute VO2 and dividing it by their body weight. This relative figure is more accurate for measuring differences amongst athletes because it does account for these differences. Two other factors that case variance are described by McArdle, Katch, and Katch (1994, p. 131) as the difference in body composition and haemoglobin levels. Hutchinson et al.

(1991) describe the size of the heart as being a major contributor to VO2 max capabilities because of its role in cardiac output.

The heart rate is important because it gives the athlete an identifiable mark, and can be used to gauge when that athlete is approaching lactate threshold (Hoogeveen, Schep, & Hoogersteen, 1999). Similarly the RPE as determined by the Borg scale can also be used a means of self-evaluation. This is because RPE according to the Borg scale usually correspond well with lactate levels and therefore the athlete can know how much harder they can push themselves before fatiguing (Billat, 1996).

In reflecting upon the results there are certain considerations that have to be taken into account. One of these as described by Billat (1996) is that the amount of training will have a direct impact upon performance. That is the more training the greater the improvements in performance. To improve upon the results attained the athlete should consider doing more training and perhaps training three to four times per week. Schneider and Pollack (1991) suggest endurance training as a means to improving the aerobic performance of athletes mentioning that it assists in delaying lactate and ventilatory thresholds. Athlete 8

In conclusion the testing that was conducted was successful in identifying and measuring results that can be used in future to re-evaluate and assess the progress that the athlete is making. Athlete 9

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