Is weakness in old age due to muscle wasting?

Grip strength and fat-free mass (FFM) were measured in 158 men and 112 women of 65 years and over living at home. There was a striking decline in grip strength with increasing age in both men and women. A marginal decline in FFM was not statistically significant. Multiple regression analysis suggested that age had an effect on grip strength which was independent of FFM. An explanation for this pattern might be that with ageing an increasing proportion of skeletal muscle is replaced by fibrous tissue, so that, although there is striking reduction in muscle power, there is only a marginal reduction in FFM.