In this weeks post I’ll talk about why aerobic fitness procedures are conducted and how you can undertake specific aerobic testing to better help you to determine your overall fitness and performance.
The assessment of VO2 max, known as ‘maximal oxygen consumption’ or ‘peak oxygen uptake’ is most commonly used as an indicator of physical performance, lactate response and functioning of an individual’s aerobic endurance capacity. VO2 is used to measure the volume of oxygen consumed by the body in milliliters per minute, relative to body mass (ml/kg/min).
VO2 max testing is a widely administered procedure, essential to examine subjects’ maximal oxygen uptake for an athlete or general based population. Population based testing can be performed simply by conducting a 20 meter shuttle run or timed walk. The result of either test can be correlated via an equation to determine the VO2 value. Using these methods of predicting of VO2 max can provide an inexpensive, accurate approach to identifying aerobic capacity in large general population.
In contrast, a clinical ‘gold standard’ test is performed in a laboratory on either a treadmill or bike ergometer with relatively small groups of test subjects. Each participant is required to wear a mouthpiece that is attached to a metabolic system which measures their respiratory gases. The system is able to measure VO2 max in absolute units (L/min) and is calculated into relative units (ml/kg/min). This type of testing can provide an extremely accurate result but only should be conduced in supervision by qualified exercise personnel with access to essential equipment.
Prior to ‘gold standard’ VO2 testing, all test subjects should be instructed to remove any shoes and unnecessary clothing before any measurements are taken to avoid skewed results. Laboratory conditions including temperature and barometric pressure are recorded prior to testing, in addition to measurements of the subject’s body mass and height.
Each participant is required to wear a heart rate monitor, as heart rate (HR) measurements will assist in determining the level of physical stress that an individual is experiencing. Resting blood lactate levels are taken using a spring loaded blood lancet to pierce the skin of the subject’s ear lobe or fingertip and assessed with a blood lactate analyzer. The level of lactate is proportional to the quantity of hydrogen ions present in the blood. Hydrogen ions can create an increase in blood acidity which can have an adverse effect on muscle contraction, thus decreasing performance.
There are several types of VO2 max testing procedures which all have their own advantages or disadvantages. It is suggested that if you are a runner or your sport includes a significant amount of running then a shuttle run or treadmill based VO2 test is more appropriate. On the other hand, if cycling is your preferred method of exercise, then the bike ergometer performed via the YMCA sub-maximal cycle test will be the optimal choice.
All VO2 max treadmill and cycle protocols conduct incremental testing which allows the subject to increase their exercise intensity over a set duration. The testing only will end when either the subject decides to end the test, or when the subject reaches volitional exhaustion and cannot physically continue.
A maximal test to measure VO2 max is often impracticable for general or older populations with detrimental cardiovascular health issues, therefore a sub-maximal test is considered a sufficient method of accurately predicting a relative VO2 max value. Although, studies have found that it is possible to obtain values for VO2 up to 10% to 15% less on a cycle ergometer compared to a treadmill VO2 protocol and therefore is at risk of underestimating the true VO2 value.
Having the knowledge to conduct VO2 maximal testing is not only a tool that all Personal Trainers should understand, but the general public should also have an idea of how to test themselves safely and accurately. The ability to perform, record and correlate fitness test results to a population average will help with overall goal setting and motivation to keep people physically active and healthy.
Marc Dressen, MSc
Personal Trainer London
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Akalan, C., Robergs, R. A., & Kravitz, L. (2008). Prediction of VO2max from an individualized submaximal cycle ergometer protocol. Journal of Exercise Physiology, 11(2), 1-17.
Hawley, J., & Noakes, T. (1992). Peak power output predicts maximal oxygen uptake and performance time in trained cyclists. European Journal of Applied Physiology and Occupational Physiology, 65(1), 79-83.
Leger, L.A., & Lambert, J. (1982). A maximal multistage 20m shuttle run test to predict VO2 max. European Journal of Applied Physiology, 49, 1-12.
Myles, W., & Toft, R. (1982). A cycle ergometer test of maximal aerobic power. European Journal of Applied Physiology and Occupational Physiology, 49(1), 121-129.
Storer, T. W., Davis, J. A.., & Caiozzo, V. J. (1990). Accurate prediction of VO2max in cycle ergometry. Medicine & Science in Sports & Exercise, 22(5), 704-712.