Effect of sex on the acute skeletal muscle response to sprint interval exercise

A few studies have reported sex-based differences in response to several weeks of sprint interval training (SIT). These findings may relate to sex-specific responses to an acute session of SIT. We tested the hypothesis that the acute skeletal muscle response to SIT differs between sexes. Sedentary but healthy men (n = 10) and women (n = 9) were matched for age (22 +/- 3 versus 22 +/- 3 years old) and cardiorespiratory fitness [45 +/- 7 versus 43 +/- 10 ml O-2 (kg fat-free mass)(-1) min(-1)], with women tested in the mid-follicular phase of their menstrual cycles. Subjects performed three 20 s 'all-out' cycling efforts against a resistance of 5% of body mass, interspersed with 2 min of recovery. Relative mean power outputs [7.6 +/- 0.5 versus 7.5 +/- 0.9 W(kg fat-free mass)(-1)] were similar between men and women (P > 0.05). Furthermore, there were no differences in the exercise-induced changes in mRNA expression of PGC-1 alpha, PRC, PPARD, SIRT1, RIP140, HSL, HKII, PDK4, PDP1, FOXO3, MURF-1, Myf5, MyoD and VEGFA at 3 h of recovery versus rest (P<0.05, main effect of time). The only sex-specific responses to exercise were an increase in the mRNA expression of GLUT4 and LPL in women only and Atrogin-1 in men only (P<0.05). Women also had higher expression of HKII and lower expression of FOXO3 compared with men (P<0.05, main effect of sex). We conclude that the acute skeletal muscle response to SIT is largely similar in young men and women. The mechanistic basis for sex-based differences in response to several weeks of SIT that has been previously reported remains to be elucidated.