To investigate muscle strength and muscle endurance in women during 3 well-determined phases of the menstrual cycle: early follicular phase, ovulation phase, and midluteal phase.
Prospective, within-woman analysis was performed of muscle strength and muscle endurance by repeated measures analysis of variance in 3 hormonally verified phases of 2 consecutive menstrual cycles.
Fifteen female subjects with moderate physical activity level and regular menstrual cycles volunteered to participate in the study. Analyses are based on 10 subjects who completed 2 consecutive menstrual cycles with hormonally verified phases.
Handgrip strength, 1-leg hop test, isokinetic muscle strength, and muscle endurance were measured in 2 consecutive menstrual cycles in the early follicular phase, in the ovulation phase, and in the midluteal phase. Isokinetic muscle strength and endurance were tested with knee extension exercise on a standard instrument. Menstrual cycle phases were determined by analysis of sex hormone levels in serum, and ovulation was detected by luteinizing hormone surge in urine.
No significant variation in muscle strength or muscle endurance could be detected during different well-determined phases of the menstrual cycle.
This study detected no significant variation in muscle strength and muscle endurance during the menstrual cycle. In contrast to other studies showing variations in strength and endurance during the menstrual cycle, the present study was hormonally validated and was repeated in 2 consecutive menstrual cycles. However, it is unknown whether these data in moderately active university students would be relevant to the highly trained woman athlete.
*Section of Sports Medicine, Division of Surgical Sciences, Karolinska Institutet, †Stockholm University College of Physical Education and Sports, and ‡Department of Obstetrics and Gynaecology, Karolinska Hospital, Stockholm, Sweden.
Received for publication September 2002; accepted January 2003.
Reprints: Cecilia Fridén, RPT, Division of Surgical Sciences, Section of Sports Medicine, Karolinska Hospital, SE-171 76 Stockholm, Sweden. E-mail: Cecilia.firstname.lastname@example.org
Supported by the Swedish National Center for Research in Sports and Swedish Medical Research Council (No. 13142), Karolinska Institutet.