1. The maximum voluntary isometric contraction (MVC) of the dominant quadriceps muscle was measured in 136 healthy White and 172 healthy Hindu Asian subjects resident in London, using a specially designed chair equipped with a force measuring load cell.
2. Males were stronger than females, and for both sexes MVC declined with age. From age 20 to 60 the annual decline in MVC ranged from 0.56% in White males to 1.5% in female Asians.
3. White subjects were stronger than Asian subjects even after correcting for the effect of age, height, weight and sex in a multi-factorial analysis.
4. Only in males did MVC correlate with height and weight. Asian women were more obese than any other group, and showed an increase in body mass index with age.
5. Twenty-two per cent of Asian subjects had marked vitamin D deficiency (plasma 25-hydroxycholecalciferol < 10 nmol/l). There was no correlation between MVC, and plasma 25-hydroxycholecalciferol.