VO2 Max, The Key To Faster Running
Article Difficulty: Moderate
🕗 3 minute read
In this article we are looking at the strongest single predictor of running performance, VO2 max. We will be looking at what exactly VO2 max is, how running training affects the physiological systems of VO2 max, and how to go about improving VO2 max through running.
VO2 max is defined as the maximal rate at which the human body can extract and utilize oxygen, with VO2 meaning ‘volume of oxygen consumed’.
V = Volume
O2 = Oxygen
Max = Maximum amount consumed
You will also commonly see VO2 max referred to as aerobic capacity. When we run, our body uses oxygen to create ATP (adenosine triphosphate), ATP is our body's energy currency and is used to fuel muscular contractions which powers our running. The more total oxygen that our body can utilize (VO2), the more ATP we can generate and the more work we can complete.
Why is VO2 max important?
A high VO2 max is a strong predictor of performance as it represents the ability of our body's cardiac and respiratory systems to supply our tissues with oxygenated blood. VO2 max is a product of the central system's (heart and lungs) ability to supply oxygenated blood to the peripheral system (muscles) and the muscles' ability to utilize the oxygen provided to produce muscular contraction. If you have two runners, and one has a significantly higher VO2 max, they will normally outperform the other as they can distribute and utilise a greater volume of oxygen during exercise, which means they can produce more energy. Although both lactate threshold and running economy contribute to performance, VO2 max is the strongest single predictor of endurance performance (4).
How does endurance training improve VO2 max?
Training improves the following (1):
1) Pulmonary Diffusion Capacity, the ability of the lungs to uptake air and exchange oxygen and carbon dioxide through the alveoli through the capillaries and into the blood. Improvements to the pulmonary system are lesser than the improvements to the other systems, but still have been shown to occur in high level athletes who's cardiac ability can supply large volumes of oxygenated blood to the body.
2) Cardiac Output, the ability of the heart to pump large volumes of oxygenated blood to the skeletal muscle. Training increases cardiac output by improving stroke volume (the amount of blood the heart can eject each beat). Cardiac output is generally considered the major limitation of VO2 max and responds profoundly to training.
3) Oxygen carrying capacity of the blood, the amount of oxygen that can be carried by the blood to the muscle. This occurs via increased total mass of red blood cells and hemoglobin.
4) Muscle’s ability to uptake and utilize oxygen. This occurs via greater capillarisation, greater mitochondria size and number, increased myoglobin, and greater enzymatic activity.
Of the mechanisms shown above, cardiac output improvement is the most significant and is generally considered the primary limiting factor of VO2 max. Because cardiac output limits our ability to supply oxygen, it has to improve in order for our VO2 max to improve. Simply put, to have a high VO2 max, you must also have a high cardiac output. This is why we see such a difference between sedentary people's cardiac output (typically around 20l/min) and those of elite athletes (up to 40l/min).
How to improve VO2 max
Research has found the most effective protocol for improving VO2 max is interval training bouts of 3-5 minutes at or around VO2 max, with rests of 2-4 minutes (2). Intervals have been found to be significantly more effective at increasing VO2 max than lower intensity steady state training (3), however the greatest effects are found when employing both interval training and low intensity training. This is because HIIT has a significant effect on increasing our cardiac output via increased stroke volume, while low intensity exercise stimulates an increase in the oxidative capabilities of muscle fibers. This is an example of the complementary mechanisms of combining both low intensity training and high intensity training. In training, your goal pace (race pace) intervals are going to be ramping up your VO2 max. The reason why this type of training is the most effective is because they make you perform at or just below your VO2 max, which means while running at this intensity, you are stressing the physiological mechanisms that supply and utilise oxygen, and this stress is what leads to adaptation. Much in the same way as how you have to lift moderate-heavy loads in the weight room to increase strength, you train near VO2 max to drive up aerobic capacity.
About the Author:
Joe is a certified personal trainer, strength and conditioning coach, and nutrition coach. While studying sport and exercise science, Joe's main focus has been on human physiology and performance. Joe has helped numerous clients achieve their health and fitness goals by applying research into practice to support their physical and overall well-being.
References
1) Bassett, D. R., Jr, & Howley, E. T. (2000). Limiting factors for maximum oxygen uptake and determinants of endurance performance. Medicine and science in sports and exercise, 32(1), 70–84.
2) Bacon, A. P., Carter, R. E., Ogle, E. A., & Joyner, M. J. (2013). VO2max trainability and high intensity interval training in humans: a meta-analysis. PloS one, 8(9), e73182.
3) Helgerud, J., Høydal, K., Wang, E., Karlsen, T., Berg, P., Bjerkaas, M., Simonsen, T., Helgesen, C., Hjorth, N., Bach, R., & Hoff, J. (2007). Aerobic high-intensity intervals improve VO2max more than moderate training. Medicine and science in sports and exercise, 39(4), 665–671.
4) McLaughlin, J. E., Howley, E. T., Bassett, D. R., Jr, Thompson, D. L., & Fitzhugh, E. C. (2010). Test of the classic model for predicting endurance running performance. Medicine and science in sports and exercise, 42(5), 991–997.