Typically, previous studies have focused on one muscle group, the finger flexors, and only one aspect of muscle function, strength, when assessing age-related muscle force production characteristics. In the present study, the maximal voluntary isometric contraction force-time curves of five muscle groups (right hand finger flexors, right thumb abductors, right forearm extensors, right leg dorsiflexors, and right leg plantar flexors) were assessed in men, ranging in age from 20 to 74 yr. One hundred fifty-three volunteers were placed into appropriate 5-yr age groups: 20-24 (N = 14), 25-29 (N = 15), 30-34 (N = 16), 35-39 (N = 13), 40-44 (N = 16), 45-49 (N = 11), 50-54 (N = 16), 55-59 (N = 12), 60-64 (N = 17), 65-69 (N = 13), and 70-74 (N = 10) years. Muscle function was characterized by a number of force-time parameters, including strength, time, rate, and impulse. The data were analyzed both with and without consideration of the influence of physique and body composition. The results indicated that there were significant age group differences in the ability to produce maximal force (strength) (P less than 0.05), to generate maximal rates of force production (P less than 0.05), and in the total forces generated (impulse) (P less than 0.05), with an overall and in the total forces generated (impulse) (P less than 0.05), with an overall decline with increasing age.(ABSTRACT TRUNCATED AT 250 WORDS)