Accession Number : ADA335874

Title :   Effect of Menstrual Cycle Phase on Muscle Fatigue and Physical Performance During High Altitude Acclimatization.

Descriptive Note : Final rept.,

Corporate Author : ARMY RESEARCH INST OF ENVIRONMENTAL MEDICINE NATICK MA

Personal Author(s) : Rock, Paul B.

PDF Url : ADA335874

Report Date : SEP 1997

Pagination or Media Count : 69

Abstract : To characterize skeletal muscle function in women during altitude exposure, 19 women (22+1 yr; mean+SE) with normal menstrual cycles were studied at sea level (SL, days 1, 5, and 9 of the follicular and luteal phases) and after 1, 5 and 9 days of continued exposure to 4300 m (days 2, 6 and 9-10 of the follicular or luteal phase). Maximal voltintary contraction force was measured before ("strength") and every min during intermittent static contraction exercise (50% of strength, 5 sec contraction/5 sec rest) of the adductor pollicis muscle and every 2 min during dynamic contraction exercise (18 + 2% of strength at a contraction rate of 1 Hz) of the quadriceps femoris muscle, to exhaustion. Major findings were: (1) strength and time to exhaustion did not vary significantly (P> 0.05) between menstrual phases or among days within each phase at SL or altitude, and (2) endurance time to exhaustion for women --- in sharp contrast to male historical controls --- was similar at altitude as at SL. (Men have a much greater reduction in endurance time). The gender difference in muscle endurance was independent of menstrual phase and remained despite men and women having identical levels of strength and exercising to exhaustion at a similar work rate

Descriptors :   *PERFORMANCE(HUMAN), *MUSCLES, *FATIGUE(PHYSIOLOGY), *ALTITUDE ACCLIMATIZATION, STATISTICAL TESTS, COMPARISON, STRENGTH(PHYSIOLOGY), HISTORY, HIGH ALTITUDE, MALES, WOMEN, SEA LEVEL, TIME STUDIES, MENSTRUATION, ENDURANCE(PHYSIOLOGY).

Subject Categories : Biology
      Anatomy and Physiology
      Stress Physiology

Distribution Statement : APPROVED FOR PUBLIC RELEASE