Gender differences in the circadian variations in muscle strength assessed with and without superimposed electrical twitches.

摘要: The circadian rhythm in muscle strength was analysed 12 males (28 +/- 4 years, 79.6 12.3 kg, 1.80 0.05 m) and eight females 60.3 5.5 1.61 0.08 m). After two familiarization sessions, participants were tested at six different times of the day (02:00, 06:00, 10:00, 14:00, 18:00 22:00 hours), order which randomly assigned over 3-4 days. Rectal temperature (T(rec)) measured 30 min before each test. Peak isokinetic torques (PT) knee extensors flexors then 1.05 rad s(-1) 3.14 through a 90 degrees range motion. Maximal isometric voluntary contraction (MVC) 60 flexion MVC also assessed with superimposed electrical twitches (50 Hz, 250 V, 200 mus pulse width) to control for motivational effects. Three trials performed condition, separated by 3 recovery, highest values retained subsequent analyses. A significant observed T(rec) both (acrophase, Phi, 17:29 16:40 hours; mesor, Me, 37.0 36.8 C; amplitude, A, 0.28 0.33 C females, respectively). mesor higher than (p < 0.05). Significant rhythms extensor PT (Phi, 17:06 178.2 N m; 4.7 15:35 128.7 3.7 In males, demonstrated rhythm, but only when 16:17 h; 302.1 13.6 Acrophases all indices not statistically between groups located afternoon (12:47 Phi 17:16 hours). amplitude (percentage mesor) (electrically stimulated) (6.4%) (4.2%; p consistently whatever gender. Our group female subjects tended show lower amplitudes males. maximal electrically stimulated muscles followed curve, without twitches. These results suggest that motivation could have masking effect on performance strengthen view peripheral factors are implicated this rhythm.