The size and strength of the quadriceps muscles of old

Abstract

The mean isometric strength of the stronger quadriceps muscles of 12 healthy men in their 70s was 39% < that of 12 healthy men in their 20s (P < 0.001). The cross-sectional area of the quadriceps was measured at mid-thigh, by ultrasound scanning; the older men''s stronger quadriceps were 25% smaller (P < 0.001). The ratio of the stronger quadriceps'' strength to its cross-sectional area was very similar in the old men to values obtained previously for both old and young women, but averaged 19% less than in the young men (P < 0.02). Quadriceps size and strength were correlated in the old men (r = 0.77, P = 0.03) but not in the young men (r = 0.15). The principal axis of the relationship between quadriceps size and strength in the old men was very similar to those previously reported for both old and young women. The quadriceps strength of some young men was greater than would be expected from the size of the muscle.