Muscle performance in an urban population sample of 40- to 79-year-old men and women.

An urban population sample of 40 to 79-year-old men and women was investigated to evaluate the influence of age and activity level on muscle strength and endurance and to establish a reference material. During the investigation 144 persons were tested bilaterally, except for ankle strength, when only the right side was examined. Isometric muscle strength was determined in the knee extensors and flexors. Isokinetic (at 60 degrees/s and at 180 degrees/s) muscle strength was determined concentrically and eccentrically in the knee extensors and flexors. The dynamic and static endurance of the extensors was measured. Isometric strength was determined in the ankle plantar and dorsiflexor muscles. Isokinetic ankle plantar flexion strength was determined concentrically at 60 degrees/s with and without prior eccentric muscle contraction. Hand-grip strength was evaluated with a dynamometer. Walking velocity and the number of heel-rises were recorded. Physical activity level was assessed by questionnaire. Muscle biopsies were taken from the vastus lateralis muscle for histochemical and enzymatic analyses. Walking and the different muscle tests declined with age, and with a slight gender difference. Muscle biopsies showed a trend toward smaller muscle fibers with age. The results of our study can be used as reference material for clinical studies in different age groups.