Figure 1
Females exhibit lower muscle endurance than males, as demonstrated by in vivo and in vitro studies. (a) Forced-swimming times of male and female Sprague-Dawley rats (n=7–8/group). (b) Treadmill-running times of male and female Sprague-Dawley rats after adaptation trainings for 1 week (n=6/group). (c) Forced-swimming times of male and female Sprague-Dawley rats after 5-day sleep deprivation (n=5−6/group). (d) Electrically evoked contractions of soleus muscle isolated from male and female Sprague-Dawley rats. The ratio of tension at 1, 2 or 3 min to the initial tension (average of the first 5 contractions) is expressed as the fatigue index. (e) Representative records of the fatigue tests in (d). Male and female rats were matched for weight. Data are presented as the means±s.e.m. *P<0.05 and **P<0.01 by Student’s t-test.
