Sport and Exercise Physiology

Question: Critically discuss methods used to determine VO2max and its application to endurance sport. Answer: Introduction: From the phrase volume of oxygen, the term VO2 is derived. The V denotes volume and O2 denotes oxygen. VO2 max value is the maximum volume of oxygen that can be utilised by a person during physical exercise. VO2 max is measured in millilitres per kilogramme of weight per minute (ml/kg/min) (Joseph 2015). During exercise as the intensity is gradually increased, the body increases the amount of oxygen intake for the production of energy. However, there is a limit to the oxygen intake at which any further increase in the intensity of exercise will not increase the oxygen intake. This final threshold of oxygen intake is the known as the VO2 max. VO2max is a crucial physical determinant of the performance of an athlete. Hence increasing the level of VO2 max is critical for athletes training regimes. VO2 max of an individual or an athlete depends on factors such as- efficiency of the physical activity, the adaptation of muscle and the metabolism rate of a person (Joseph 2015). Discussion: Endurance sports are a subgroup of sports in which the aim is to attain athletic output over a prolonged period or distance. The most vital factors that benefit the endurance sports are its intensity (Joseph 2015). Training with a suitable intensity optimises the response of the body to attain the highest endurance. Testing the amount of intensity is the best way to learn about the most efficient training regime of an individual according to his or her physiologic conditions. The intensity of physical activities of a person can be determined by measuring the amount of oxygen intake that by measuring the VO2 max. The VO2 max value can shed light on the performance of an individual. Hence, the VO2 max values are imperative for determining the performance level of an athlete. It is crucial for an athlete to monitor their VO2 max value to keep a log on their performance (Joseph 2015). The VO2 max values can be measured using the following methods: Astrand treadmill test This test is conducted to measure the value of VO2max. Requirements of this test are a treadmill, a stopwatch and an assistant. In this test, at first for ten minutes the athlete warms up. Then the athlete runs on a treadmill which is at the speed of 8.05km/hr and an inclination of 0%. The time is recorded using a stopwatch and the inclination is changed by 2.5% every 3 minutes by the assistant till the athlete can run (strand and Ryhming 1954). The VO2 max is calculated using the following formula: VO2 max= (time* 1.444) + 14.99 Astrand 6 minute cycle test The requirements of the Astrand 6 minute cycle tests are cycle ergometer, stopwatch, heart rate monitor, weighing scales and an assistant. The athletes weight is measured first, and then the athlete is needed to warm up for ten minutes (strand and Ryhming 1954). Next, the cycle work rate is set by the assistant in kilogram-force metre per minute (kg-m/min) according to the following criteria: Male over 55 85 Male 35-55 115 Male under 35 125 Female over 55 60 Female 35-55 85 Female under 35 115 The setting of the cycle will increase the heart rate of the athlete to 130-160bpm after 2 minutes of cycling at a speed of 60 rpm. Then the assistant starts the stopwatch and commands the athlete to start. Keeping the heart rate between 130- 160 bpm the athlete pedals for 6 minutes at 60 rpm. The heart rate of the athlete is recorded every minute. The assistant changes the work rate wattage of the cycle if the heart rate of the athlete changes from the given range. The test is stopped after 6 minutes and the final work rate wattage is recorded. The VO2 max is calculated from all these factors (strand and Ryhming 1954). 2.4 km run test Requirements of this test are a 400-meter track, an assistant and a stopwatch to record the time. The athlete runs 2.4 km after warming up for 10 minutes. The time taken to complete the 2.4 km run and each lap is recorded by the assistant (Burger et al. 1990). The VO2 max is calculated using the following formula given by Burger et al. (1990): VO2max = 85.95 - (3.079 x Run Time [minutes]) {2.24-2.91 ml/kg/min}. Balke VO2 max test Prerequisites of this test are a 400m track, whistle, stopwatch and an assistant. In fifteen minutes the athlete needs to run as far as he or she can go. The assistant records the distance the athlete covered in 15 minutes (Horwill et al. 1992). The VO2max is calculated from using this distance which was given by Horwill (1992) as following: VO2max = [{(Total distance covered 15) 133} 0.172] + 33.3 Balke incremental treadmill protocol test In this test, the athlete runs on the treadmill for as long as he or she can. The inclination of the treadmill is incremented at appropriate intervals of time. The slope of the treadmill is set 0% initially and then incremented by 1%ebery minute for men and 2.5% for women every 3 minutes. The speed of the treadmill is set at 3.3 mph for men and 3 mph for women (Pollock et al. 1976). When the athlete stops running, the time is recorded. Using the following formulas given by Pollock et al. (1976) the VO2 max is calculated. VO2 max = 1.444 T +14.99 (for men) VO2 max = 1.38 T + 5.22 (for women) Cooper VO2 max test The resources required for this test are 400-metre track, whistle and stopwatch, and an assistant. The athlete needs to run for 12 minutes as far as it is possible (Cooper et al. 1968). Before starting to test, warm up for ten minutes is done. The assistant signals the athlete to stops by blowing the whistle after 12 minutes. Then the assistant records the distance covered by the athlete in 12 minutes (Cooper et al. 1968). The VO2 max value is calculated by using the following formula given by Cooper et al. (1968): (Distance covered in metres - 504.9) 44.73 VO2 max step test The prerequisites of this test are an assistant, a 16 inch high step or bench, stopwatch, and a heart rate monitor. The athlete is required to step up and down on the bench for 3 minutes with one foot at a time. This is done in a 4 beat cycles, men 24 steps/minute and women 22 steps/minute (McArdle 2000). After 3 minutes, the heart beat for 15 seconds is recorded. The heart beat is multiplied with 4 to determine step test pulse rate. The value obtained is used to calculate the VO2 max. Using the following formula given by McArdle (2000) the VO2 max is calculated. Male = 111.33 - (0.42 x pulse rate beats/min) Female = 65.81 - (0.1847 x pulse rate beats/min) VO2 max from race result VO2 max can be calculated from race results by recording the time and distance of the race. An athlete is needed to race for more than once. All the race results are used to determine the VO2 max value. VO2 max from one-mile jog In this test, firstly the weight of the athlete is recorded and then the athlete warms up for10 minutes. Next, the athlete starts to jog for one mile at a steady pace ensuring that they jog for more than 8 minutes (men) and 9 minutes (women) (George et al. 1993). An assistant records the time after completion of one mile and immediately checks heart rate of the athlete and records it. The VO2 max is calculated by using algorithms given by George et al. (1993). VO2max = 108.844 - 0.1636W - 1.438T - 0.1928H (Male Athletes) VO2max = 100.5 - 0.1636W - 1.438T - 0.1928H (Female Athletes) (W= Weight, H= Heart rate and T=Time) Treadmill VO2 max test In this test, the athlete needs to run on a treadmill whose slope and speed can be adjusted for as long as possible by the athlete. At every one minute the slope of the treadmill is increased exponentially at 0 minutes 0 degree, 1 minute 2 degree, 2 minutes 4 degree and so on (Joseph 2015).. The athlete stops running when it is no more possible to run. The final time is recorded. The VO2 max value is calculated from the following expression: VO2max = 42 + (Time 2) Multistage Fitness Test or beep test The prerequisites for multistep fitness test are a 30-metre tape measure, flat no-slip surface, the multistage fitness test CD, marking cones, CD player, a person to assist in recording the results. A track is made with marking cones at 20-meter intervals. Firstly, for ten minutes the athlete warms up. Then the athlete is required to run 20 metres at a time accordingly with the beep signals from the audio tape or CD (kilding et al. 2006). The athlete starts running when the assistant initiates the audio. The number of the shuttles which is completed by the athlete is recorded by the assistant. If the athlete reaches a marking cone before the beep, then he must wait for the signal before running the next 20 metre. If the athlete reaches the marking cone after the beep, he is allowed 2 -3 shuttles to regain the required pace. The VO2max is calculated by using the following formula given by (kilding et al. 2006): VO2max (mL/kg/min) = 0.38 x total number of shuttles completed + 25.98 Rockport fitness walking test In this test, the athlete walks 1609 metres (one mile) as fast as possible. Before starting the walk, the weight of the athlete is measured, and the athlete warms up for 10 minutes. The time required by the athlete to complete the one-mile walk and the heart rate of the athlete immediately after the completion one-mile walk is recorded by the assistant (Joseph 2015). The following formula is used to determine the VO2 max of the athlete: 132.853 - (0.0769 Weight) - (0.3877 Age) + (6.315 Gender) - (3.2649 Time) - (0.1565 Heart rate) Application of VO2 max Endurance athletes use their VO2 max values to determine their functional capability. The ability to use VO2 max value to determine their performance level acts as a gauge of their future performance and progress (Joseph 2015). An athlete can determine their performance level by using only VO2 max values or by the combination of VO2 max and absolute lactate threshold values. These parameters can give an idea about the caloric needs, optimal energy source usage and heart rate training zones. All these factors can be incorporated into training programs to attain peak endurance level. Factors like genetics recovery and rest also play a role in the peak performance of an athlete along with the above factors (Joseph 2015). When endurance sports are played by athletes, their body uses glucose to produce energy. The glucose production requires oxygen. However, when athletes increase the intensity of effort they put in a sport, their muscle cell produce glucose without oxygen. It leads to a byproduct that is lactate. When level increases in the blood, the athletes lactate starts to feel fatigue (Joseph 2015). The immediate spike of lactate concentration in the blood is the lactate threshold point. The lactate threshold value depends on the VO2 max value, as when oxygen intake stops increasing, the lactate production begins. Hence, both these factors influence the performance of endurance athlete. VO2 max values are practically crucial for training regimes of an athlete. By estimating their VO2 max values, athletes can improve their performance over time through training so that their VO2 max threshold increases. It determines an individuals maximum aerobic capacity (Joseph 2015). Conclusion: The size of the engine of an athlete is determined by the VO2 max value. When an endurance athlete acquires his or her VO2 max value, they can estimate their current capacity. This estimation helps the athletes to plan their training regimes so that they can improve their functional capability as an athlete. VO2 max values also can be used to determine the heart rate training zones of an athlete. This determination helps the athletes to minimize fatigue and maximise performance by understanding the abilities and limits of their bodies. The heart rate directly proportional to the VO2 max until the threshold point of the athlete is reached. An assessment of VO2 max values of athletes enables them to train smartly rather than just working hard. 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