Lack of variation in muscle strength with menstrual status in healthy women aged 45-54 years: data from a national survey.

Isometric handgrip, quadriceps muscle strength and leg extensor power were assessed as part of a large representative survey of adult men and women in England. The gender ratios for these muscle strength measurements did not differ across age groups, which ranged from 25 to 65 years. Data from a subsample of women who were aged between 45 and 54 years and free of major health problems or current gynaecological problems (n = 299) and were analysed to see if there were differences in the muscle measurements according to reported menstrual status. Analysis of variance was used to compare four subgroups of women as follows: those who were still menstruating regularly (n = 89), those who had stopped altogether (n = 92), those who were irregular (n = 33) and those on hormone replacement therapy (n = 15). No significant differences were found between these subgroups in any of the three muscle measurements, body mass, fat-free mass (derived from four skinfolds), body mass index, or customary activity levels. There was a significant age difference of 2 years between two subgroups. After having controlled for this, using analysis of covariance, the outcome was not changed. These women were also compared with men in the same age range; the women had about 60% of the strength of the men and a highly significant difference remained after controlling for fat-free mass in all subgroups. No evidence was found for an ergogenic effect of the high oestrogen status conferred by natural menstruation or hormone replacement therapy.