Muscle morphology, enzyme activity and muscle strength in elderly men and women

Abstract

Summary.The quadriceps muscle were investigated with respect to isometric and isokinetic muscle strength, morphology and as regards some enzymes and metabolites of importance for the contractile processes. The material comprises 52 men (66–76 years) and 13 women (61–71 years) without clinical symptoms. Some participants used antihypertensive and/or heart‐regulating medicine but were symptom‐free. None of the subjects participated in any systematic training. All of them except for one physically inactive woman carried out moderate physical activities for at least 4 hweek. The body cell mass was higher in the men than in the women, and was highly correlated to muscle strength in both sexes. The fibre distribution was similar in both sexes with an average of 48 % Type I fibres in the men and 54 % Type I fibres in the women. The women had fewer Type II B fibres (4%) than the men (18 %). The average Type I fibre area did not differ between the sexes. The average Type II fibre area and the mean fibre area were smaller in women than in men, so that the ratio between the mean Type II and Type I fibre area was smaller in the women (0–76) than in the men (0–95). Signs of denervation/reinnervation, such as type grouping and an increase number of enclosed fibres, were observed very rarely and no great number of atrophic fibres indicating neuropathy was found. In both sexes, there was a reduction in the Type II fibre size, specially in relation to Type I fibre size, compared with young people. There was no difference between the enzymatic (Mg2+ATPase, MK and LDH) and the phosphagen (ATP and CP) content values between the sexes and no correlation between these variables and muscle strength. The capillarization was similar in the men and the women.