The aging process raises several changes in skeletal muscle leading to a loss of muscle function and a reduction in muscle mass (sarcopenia). This impairs quality of life and increases morbidity of elderly people. Strength training has been shown to counteract the age-dependent muscle degeneration. We examined whether the intensity of strength training differently influences cellular adaptation of skeletal muscle in older persons.

24 healthy older men (age 74 +/- 3 yrs, BMI 26 +/- 1 kg/m²) were randomly assigned to a moderate strength training group (MsG, training 2x week, 60-65% of 1 repetition maximum (RM)) and an intense training strength group (ISG, training 2x a week, 80-85% 1RM ) each. The training was carried out over a period of 12 weeks. Cardiovascular function was measured by bicycle spiroergometry (WHO-scheme, start at 25W, increase every 3 min. by 25 W until subjective or symptom limited exhaustion). Skeletal muscle function was measured by hand grip strength, leg and chest press. In addition, the adaptation of skeletal muscle was examined by muscle biopsies from the M. vastus lateralis using immunohistochemical methods.

The age-adjusted bicycle ergometer performance was in the normal range for the two groups and did not change after the training intervention. In both groups, strength training induced a significant increase in the relative maximal oxygen uptake. Both strength training groups showed significant improvements in the strength of the muscles of the upper and lower extremities. There were no significant group differences. None of the training groups showed a significant change in grip strength or gait speed. Evaluating exemplary muscle biopsies showed that the resistance training induced no shift of the muscle fiber type. Only in the group of moderate force, there was a significant increase in muscle fiber diameter of both type 1 and type 2 muscle fibers.

Conclusions: Strength training improves muscle function and oxygen uptake in elderly healthy men. This seems to be independent from the training intensity and hypertrophy of skeletal muscle.