When you first begin doing aerobic exercise, you tire quickly and have to stop prematurely. But with repeated training, your exercise tolerance increases and you can work out at the same intensity without fatiguing so quickly. Not only are you fitter, but you’ve also improved your aerobic capacity. Why is this important? During exercise, your muscles need more oxygen. The maximum amount of oxygen your body can take in, transport and use during exercise is referred to as V02 max and it’s an indirect measure of your aerobic capacity.
V02 max can be measured in a laboratory using a graded exercise test while measuring oxygen consumption. When oxygen consumption plateaus despite an increase in workload, you’re at your V02 max. As you might expect, elite endurance athletes usually have higher a V02 max than the average person, although other factors also affect endurance performance. Unfortunately, we’re not all born with the V02 max of an elite athlete, but most people can certainly increase their aerobic capacity through training. How much CAN you increase your V02 max through exercise?
What Factors Affect Aerobic Capacity?
When you train regularly, a number of improvements take place that improve your V02 max. For one, your heart becomes capable of pumping more blood to your hard-working muscles. This is due mainly to an increase in stroke volume. You experience a slight increase in the size of your left lower heart chamber, or left ventricle, as well as an increase in plasma volume as a result of training. The increase in plasma volume stretches the left ventricle and increases the volume of blood your heart ejects with each beat. This sends more oxygenated blood to your muscles.
Other changes that increase V02 max occur peripherally, at the level of the muscle. With regular aerobic exercise, capillary density around muscle increases. This improves oxygen delivery to muscles. Plus, the number of mitochondria inside cells that use this oxygen to make ATP increase. As a result of training, more oxygen is delivered to muscles and they have a greater capacity to use it to make energy as a result of more mitochondria.
Some People Have a High V02 Max without Training
There are a small number of individuals who have high V02 max’s without training at all. How can you explain this? One theory is these individuals have the ability to direct a greater portion of their blood volume to working muscles during exercise. Most of us don’t have that ability and have to boost our aerobic capacity and V02 max through exercise training.
What happens when you stop training? Your V02 max decreases over time. When we put our exercise shoes aside and lie on the couch for a few weeks, plasma volume goes down. This decreases stroke volume and the amount of oxygenated blood the heart can deliver to hungry muscle cells. Plus, the number of mitochondria inside muscle cells that produce energy decrease in number and you start to experience a decline in exercise performance.
The degree to which you can improve your V02 max varies and is based on genetics and the intensity of your training. The average person can expect to improve their aerobic capacity by 15 to 20% – but there’s a great deal of variation in how much a person can improve. A study called the Heritage Family Study found there’s a probable genetic component to how much improvement in V02 max you can get through training.
People within the same family can expect to have somewhat similar improvements in aerobic capacity as a result of exercise training. In fact, genetics accounted for about 50% of a person’s response to training. Surprisingly, there are some people who improve minimally or not at all even when they train. These individuals were referred to as “low responders” to aerobic exercise training. In the Heritage Family Study, some individuals even had a DECREASE in V02 max after training. Fortunately, most people can expect some improvement in their aerobic capacity when they train regularly.
What’s the Best Way to Improve V02 Max?
Long periods of low to moderate intensity exercise aren’t the best way to improve aerobic capacity. To maximize the benefits, do high-intensity interval training – alternating challenging, intense intervals with short periods of recovery. A study showed that high-intensity aerobic exercise improved V02 max more than less intense prolonged exercise. Once you’ve maximized your V02 max through high-intensity training, you need as little as one high-intensity interval workout a week to maintain it.
Research also shows that Tabata training, like my Tabatacice DVD, increases V02 max and you can get the benefits by doing several 4-minute Tabata drills (20 seconds near-maximal work with 10 seconds recovery) one or two times a week. Tabata training has the added benefit of improving anaerobic capacity as well. Plus, they’re time expedient.
The Bottom Line?
Most people are able to improve their aerobic capacity and V02 max through training, on average about 15 to 20%. A small number of individuals appear to be low or non-responders to training, although they still get the other health benefits that exercise offers. Who responds and how much improvement they get is partially due to genetics. The best way to maximize your aerobic capacity is with high-intensity aerobic exercise. So put on your exercise shoes and do some interval training.
Med Sci Sports Exerc. 2007 Apr;39(4):665-71.
Exercise Physiology: Theory and Application to Fitness and Performance. Seventh Edition. Powers and Howley. (2009)