Serum Creatine Kinase Increases after Acute Strength Training in College Athletes with Menstrual Irregularities

Abstract

Chronic menstrual dysfunction and low female sex hormones adversely affect muscular performance in women but studies in college athletes are scarce. A cohort of 18 Japanese, female college athletes at the University of Tsukuba, Japan, were recruited and studied over 3 weeks under 2 conditions. One group had normal menstrual cycling (CYC, 9 athletes) while the other had irregular cycles (DYS, 9 athletes). Hormones and creatine kinase (CK) were measured from blood under both rest (RE) and exercise (EX) conditions. Biceps femoris tendon stiffness was measured by myometry. No differences in age, height, weight, menarche age, or one-repetition maximum weight existed between the groups. The DYS group had persistently low levels of estrogen and progesterone. In the CYC group, the CK level significantly increased at each point immediately post-exercise and 24 h post-exercise compared to pre-exercise in Weeks 1 and 2, and significantly increased at 24 h post-exercise compared to pre-exercise status in Week 3. The DYS group was significantly different only between pre-exercise and 24 h post-exercise over all 3 weeks. The DYS group also suffered from higher biceps femoris tendon stiffness at 24 h post-exercise. Chronic menstrual irregularities in Japanese college athletes increase muscle damage markers in the bloodstream and muscle stiffness after acute strength training.

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