MUSCLE PERFORMANCE AND STRUCTURE IN THE ELDERLY AS STUDIED CROSS-SECTIONALLY AND LONGITUDINALLY

Longitudinal and cross-sectional studies of muscle performance and str ucture in the elderly are summarized in this article. Muscle strength and muscle mass decrease with age, mainly due to the loss of muscle fi bers. In most studies of the vastus lateralis, the mean fiber area dec reases only sightly with a larger reduction in the type II fiber area, with the type I fiber area being constant. However, other fiber area patterns have also been recorded, such as the preserved type II fiber area in the biceps brachii muscle, which is larger than the type I fib er area. An increase in fiber areas was recorded in 76- to 80-year-old men who maintained their physical activity level rather well. The mus cle enzyme levels of the muscles studied also vary, and show adaptatio n with training. in particular, oxidative enzymes seem to be well main tained in old age. General conclusions concerning aging effects should not be drawn from measurements in only one muscle, and the impact of the current physical activity level of the subjects should always be t aken into account.