Is the gender difference in peak {Mathematical expression} greater for arm than leg exercise?

Based on observations that the difference between men and women in estimates of arm musculature is greater than the difference in leg musculature, it was hypothesized that the gender difference in peak oxygen uptake ( {Mathematical expression}; l · min^-1) would be greater for arm exercise than leg exercise. To test this hypothesis, 19 (10 men, 9 women) highly trained swimmers (HT) and 20 (10 men, 10 women) untrained students (UT) were tested for peak Vo2 on cycle and arm-crank ergometers. Arm and leg fat-free volumes (FFV) were measured to provide an estimate of muscle distribution. No gender difference was observed in either the arm-to-leg peak {Mathematical expression} ratio (0.699 for the men vs 0.696 for the women) or in the arm-to-leg FFV ratio (0.410 for the men vs 0.402 for the women). Although the proportion of musculature in the arms as assessed by the FFV appeared to be the same in men and women, the similarity in muscle distribution was probably not responsible for the identical average arm-to-leg peak {Mathematical expression} ratios. The variance in the muscle distribution accounted for only 2-4% of the variance in the arm-to-leg peak {Mathematical expression} differences within individuals. We conclude that factors other than arm and leg muscle dimensions account for the variability in the arm-to-leg peak {Mathematical expression} ratio and that the gender difference in peak {Mathematical expression} is the same for arm and leg exercise.