Effect of menstrual cycle on muscle strength

The purpose of this study was to compare the maximal voluntary contraction of lower limbs pre-, during, and post-menstruation periods. Twelve healthy females who have been involved in resistance training for more than 3 yrs were involved in this study. All the subjects presented regular menstrual cycles lasting between 26 and 30 days (mean: 28), and were not taking oral contraceptives. The subjects performed a maximal voluntary contraction test of the lower limbs in a Leg Press 45º during different periods of the menstruation cycle in a randomized order. For the purpose of this research, the timing of data collection was defined as: (a) pre-menstruation period (late luteal phase); (b) during the menstruation period (early follicular phase); and (c) post-menstruation (mid-follicular phase). The maximal voluntary contraction produced in the course of the early follicular phase (237.89 ± 50.15 kg) was significantly greater (P=0.01) than the contraction produced in the course of the late luteal phase (220.97 ± 46.63 kg). Moreover, the maximal strength produced post-menstruation in the mid-follicular phase (248.26 ± 48. 39 kg) was greater (P=0.01) than the force produced during menstruation and pre-menstruation periods. The data suggest that the menstruation cycle can alter the maximal muscle force capacity in women who are not using oral contraceptives. This study may have implications for women involved in resistance training who are undertaking sequential structured periodization training based on the manipulation of repetition maximal loads.