Relationships among strength, endurance, weight and body fat during three phases of the menstrual cycle.

The purpose of this study was to investigate the relationships among body weight, body fat, and dynamic strength and muscular endurance during different phases of the menstrual cycle. Twenty-one female subjects, ages 18-36, with normal menstrual cycles and no dysfunction were tested for strength and endurance of the knee flexors and extensors on a Cybex II isokinetic dynamometer. Body weight and percent body fat were also assessed. Each subject was tested at three speeds (60 degrees, 180 degrees, and 240 degrees/sec) during three phases of the menstrual cycle: mensus (within 24 hours of onset); ovulation (13-14 days from onset); and luteal (10 days from ovulation). The data were analyzed descriptively and by Pearson Product-Moment Correlations with each phase of the cycle and between cycle phases. Results indicated high correlations among most strength measures at the three test speeds for each phase during the cycle and between the cycle phases. Overall, the different phases of the menstrual cycle had little or no effect upon the relationships among body weight, percent body fat, knee extension and flexion strength or endurance.