Effects of menstrual phase on performance and recovery in intense intermittent activity.

Game sport and training require repeated high intensity bursts. This study examined differences between high intensity, intermittent work in two phases of the menstrual cycle. Six physically active young women (age 19-29) performed 10 6-s sprints on a cycle ergometer in both the mid-follicular (FP) (days 6-10) and late-luteal phases (LP) (days 20-24) of the menstrual cycle. Work, power, oxygen intake (VO2) parameters, and capillarized blood lactate were measured. Data are analyzed using the Friedman and Wilcoxon matched pairs tests. There was no difference between menstrual phases in peak 6-s power (6.8(0.6) W kg(-1) in FP, 6.9(0.6) W kg(-1) in LP), the drop off in work (1.2(3.5) J kg(-1) in FP and 1.0(2.7) J kg(-1) in LP), or in the sprint VO2 (23.7(1.5) mL kg(-1) min(-1) in LP and 24.3(2.4) mL kg(-1) min(-1) in FP). Capillarized blood lactate was also similar in both phases of the menstrual cycle both at 1 min (9.2(2.7) mmol L(-1) in FP, 9.2(3.1) mmol L(-1)) and at 3 min (9.0(2.2) mmol L(-1) in FP, 9.2(2.2) mmol L(-1) in LP). However, the average 6-s work was greater in the LP (39.3(3.4) J kg(-1)) than during the FP (38.3(3.1) J kg(-1)) (P=0.023). The recovery VO2 was also greater in the LP than the FP (26.3(2.4) mL kg(-1) min(-1) in LP, 25.0(2.6) mL kg(-1) min(-1) in FP, P=0.023). Average work over a series of sprints and the VO2 consumed between sprints may be slightly greater during the LP than the FP of the menstrual cycle.