Comparing the composition of leg muscles in young, old, and very old men

Abstract

Cross‐sectional studies report varying degrees of muscle atrophy in different muscles but usually involve the comparison of one young with one old age group. Using serial sections obtained by MR imaging, the cross‐sectional areas (CSA) of contractile and non‐contractile tissues in the anterior (ANT), lateral (LAT), and posterior (POST) compartments of the leg were measured in 38 men with ages averaging in their 3rd, 7th or 9th decades (young, old, and very old, respectively). Tissue type and compartment borders were distinguished visually and traced manually. Contractile CSA for each compartment was similar between the young and old groups, but was significantly reduced between 15–28% for all compartments in the very old. There was a significant increase in the non‐contractile tissue in all compartments across the age groups which were 1–5% from young to old and a further 5–10% between the old and very old. The greatest change was observed in the POST compartment and the smallest change in the ANT compartment. With two groups of older adults, these data demonstrate that skeletal muscle CSA in the leg is moderately well preserved until about 65y of age when there is an increased rate of deterioration. Previous studies have not compared changes in these 3 compartments of the leg. It is clear that not all muscles show similar degrees of age‐related changes which likely has functional implications.