Testing someone’s VO2max allows you to measure how much oxygen they burn at any given heart rate during exercise, giving them the most precise estimation of caloric burn during their workout. By doing so they will not have to pay attention to those calories burnt readings on the treadmills again. Even if losing weight isn’t their thing, or they’re an endurance athlete wanting to measure their cardiovascular fitness level, this is the way to go. By testing it frequently they will be able to monitor the success of their current training program. Given a case study in EXSC 510 in regards to Jordan Smith and why the exercise physiology lab discovered his VO2max was 45ml/kg/min leaves one to believe he is an average middle aged guy (assumed) who is somewhat active. I will start out by explaining how he got to his current exercise tolerance. Then explain how the test could vary if the test was conducted at altitude and Jordan lives at sea-level.
There are many things that are taken into consideration when testing ones VO2max. First, gender is a huge variable. It’s been proven that a males VO2max is typically 40-60% higher than women (Howley & Powers, 2018). The difference being, the variance in bodyweight and lean body mass. Therefore research shows that the average untrained male has a VO2max of about 45ml/kg/min. Secondly, training in different temperatures changes the results. High temperatures lead to two complications, hypothermia and dehydration. Increased body temperature leads to reduced muscle strength, which means the muscle’s capability to contract continually over long periods of time (Howley ; Powers, 2018). High body temperature results a decrease in blood movement to the heart as blood gathers in the extremities. Oxygenated blood can’t get back to the muscles if the heart isn’t getting as much blood. Dehydration causes a reduction in VO2max. In layman’s terms means that the body can’t use oxygen as proficiently to provide energy.
When bringing Jordan back into the equation and seeing his VO2max results are 45ml/kg/min this would make me believe that either he is just an average guy who doesn’t workout much or that he lives at sea-level and his VO2max was tested at a higher elevation.
Stroke volume is a measurement of how much blood the heart pumps out of the ventricle with each beat (Howley & Powers, 2018). Therefore, cardiac output is the product of heart rate and stroke volume. If we base Jordan’s VO2max on the fact that it was tested at a much higher altitude we can assume that he is much more active than stated previously. VO2 max declines with altitude. This decrease is mainly due to a descending slide in maximal cardiac output. Since we just learnt that cardiac output is dependent upon stroke volume, this would make sense given the fact that stroke volume is decreased at high altitudes due to the immediate lowering of blood plasma volume. In fact, plasma volume can decrease by as much as 25% within the first few hours of exposure to altitude, and requires a few weeks to plateau. A decrease in one’s maximal heart rate is also detected at higher altitudes, such that the general effect is a smaller amount of oxygen being released from the blood into the muscles. A smaller number of available oxygen molecules per given amount of air means that increased breathing is required to consume the same amount of oxygen to which the body has become familiarized with at sea level.
With all of these altitude-related changes occurring while the body is at rest, it is easy to see how exhaustive exercises could really impact an athlete’s performance. While it seems that strength and the ability to perform short, intense activities are not particularly affected by altitude, long-term aerobic work is significantly hindered at higher altitudes. Thus, powerful functional training engaged in at higher altitudes must permit for these modifications. VO2max can definitely be applied as a training tool. It’s just one more outline in a list of cardio-respiratory functions that can help a competitor increase that highly desirable competitive lead!
Powers, S.K., Howley, T.K. (2018). Exercise Physiology: Theory and Application to Fitness and Performance. New York, New York: McGraw Hill Education.