Thompson, Dixie L. Ph.D., FACSM
Dixie L. Thompson, Ph.D., FACSM, is the director of the Center for Physical Activity and Health and an associate professor in the Department of Exercise, Sport, and Leisure Studies at the University of Tennessee, Knoxville.
This is the second of a three-part series examining maximal oxygen consumption, abbreviated as V̇O2max. In the last issue, I described what V̇O2max is and how to measure it. This column will explore links between V̇O2max, health, and performance. In the third column, a description of how to improve V̇O2max will be provided.
V̇O2max is defined as the highest rate at which O2 can be taken in and used during high-intensity dynamic exercise. Although V̇O2max is not the only important measure of overall fitness, it is generally considered the best measure of cardiovascular fitness. A healthy, strong cardiovascular system is essential for a high V̇O2max; therefore, it is not surprising that V̇O2max is linked to both good health and exercise performance.
Symbol V̇O2max and Health
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The Aerobics Center in Dallas, Texas has conducted a number of investigations demonstrating that V̇O2max is linked to health. The researchers determined V̇O2max in thousands of men and women and then tracked their health for a number of years. The least fit men were 3.4 times more likely to die early compared with the most fit men. The least fit women were 4.6 times more likely to die early compared with the most fit women. Low fitness has been linked with the development of hypertension, coronary artery disease, and cancer. The good news is that when low-fit people become more fit, their chances of developing these diseases drop dramatically.
In addition to avoiding disease, having a healthy V̇O2max is an indicator of the ability to maintain independence with aging. We all experience a decline in V̇O2max as we get past our 30s. If V̇O2max declines below a critical point, individuals can no longer perform the tasks necessary for independent living. Maintaining an active lifestyle into later life helps preserve V̇O2max and delays the need for assistance with activities of daily living.
Symbol V̇O2max and Performance
V̇O2max is reflective of a person's maximal ability to generate energy aerobically, in other words with oxygen. In all-out efforts lasting three minutes or longer, the majority of the energy needed for muscular activity comes from aerobic processes. Performance in moderate-length and longer events of many types (e.g., bicycling, running, or swimming) is impacted by a person's V̇O2max. For example, in events such as a 5K run, competitors will run at or near their V̇O2max for the entire race. Clearly, in these types of events a high V̇O2max would give a competitor an advantage.
In longer events such as a marathon, participants must maintain a pace that is below their V̇O2max so as to avoid a build-up of lactic acid, because this can lead to fatigue. A person's genetics and the quantity and quality of training will determine what percentage of V̇O2max he or she can maintain during an endurance event. In a situation where one runner has a V̇O2max of 60 ml/kg/min and another has a V̇O2max of 70ml/kg/min, assuming all other things are equal, if both run at 75% of V̇O2max, the one with the higher V̇O2max will finish the course faster.
However, rarely are all things equal. Runners differ in their economies of running, and factors such as motivation, environmental conditions, and nutritional status significantly impact performance. In the next Fitness Focus column, I will describe training programs commonly used to improve V̇O2max.