Abstract
The purposes of this study were to examine the relationship between physical activity level (PAL) and isometric peak torque (PT) of the knee extensor (KE) and ankle plantar flexor (PF) muscles of people 51 to 90 years of age, and to examine changes in PAL and PT by decade of age for men and women. Isometric PT of the KE and PF was measured using the Minnesota System for Isometric Muscle Strength (SIMS). Seventy-nine healthy subjects (39 men and 40 women) were tested. PT decreased as age increased. The correlation between PAL and PT was significant for both muscle groups for all 79 subjects. The women showed a progressive decline in both PAL and PT. The PAL of men changed very little until the age of 80, and decreased rapidly between the 8th and 9th decades of life. PT appeared to gradually decrease up to age 80 and decline more rapidly between the 8th and 9th decades of life. Thus PAL and PT of the knee extensors and ankle plantar flexors decrease in a similar pattern with age.