| Abstract: | To determine upper body peak O2 uptake (VO2) in a group of young females and to obtain information on possible sex differences, 40 subjects, 20 females and 20 males, mean age 26 +/- 4 (SD) and 31 +/- 6 yr, respectively, were studied during maximal arm-cranking exercise. Peak values for power output, VO2, minute ventilation (VE), and heart rate (HR) were determined for each subject. In addition, arm-shoulder volume (A-SV) was measured before exercise. Significant differences between males and females (P less than 0.05) were found for peak power output (134 +/- 18 vs. 86 +/- 13 W), peak VO2 expressed in liters per minute (2.55 +/- 0.45 vs. 1.81 +/- 0.36) and milliliters per kilogram per minute (34.2 +/- 5.3 vs. 29.2 +/- 4.9), peak VE (95.4 +/- 14.5 vs. 70.1 +/- 19.2 1 X min-1), and A-SV (3,126 +/- 550 vs. 2,234 +/- 349 ml), whereas peak HR was not significantly different between the two groups (174 +/- 14 vs. 174 +/- 36 beats X min-1). However, when peak VO2 was corrected for arm and shoulder size there was no significant difference between the groups (0.82 +/- 0.13 vs. 0.78 +/- 0.13 ml X ml A-SV-1 X min-1). These results suggest that the observed differences between men and women for peak VO2 elicited during arm cranking when expressed in traditional terms (1 X min-1 and ml X kg-1 X min-1) are a function of the size of the contracting muscle mass and are not due to sex-related differences in either O2 delivery or the O2 utilization capacity of the muscle itself. |
