Gender Differences in Aerobic and Work Capacity During Plantar Flexion Exercise

Abstract

Maximal oxygen consumption (VO2max) is lower in females compared to males during traditional whole body, systemic exercise. These differences in VO2max between men and women are still present even after correcting for differences in fat and muscle mass and are due, in part, to central limitations in oxygen delivery in females. Many of these limitations can be avoided by evaluating exercise in an isolated muscle groups. At rest and maximum in the forearm, both men and women have the same relative oxygen consumption and blood flow. There are some differences in the calf at rest; both males and females have the same relative oxygen consumption, however females receive a higher relative blood flow. To investigate if inherent skeletal muscle differences exist between men and women, we measured VO2 and power output during graded treadmill and calf plantar flexion exercise to maximum. It was hypothesized that the relative aerobic and work capacity of the calf would be lower in women compared to men. During treadmill exercise, men had greater absolute VO2 and power output at maximum and when expressed relative to fat free mass (FFM), there was no difference in power output between genders, but differences in VO2max persisted with men still being higher. During plantar flexion exercise, men again demonstrated greater absolute VO2 and power output at maximum and when expressed relative to calf FFM there was no difference in either VO2 or power output between genders. It is concluded that there are no inherent muscle differences in aerobic or work capacity between men and women suggesting that differences in absolute aerobic and work capacity are not due to gender, but rather differences in muscle mass