Aging-Related Changes in Muscle Strength: A Comparison Between Young and Elderly Individuals

Objectives: Few studies have investigated aging-related changes in muscle strength. The purpose of this study is to measure muscle strength in young and elderly individuals to clarify the differences in aging-related muscle weakness across various muscles.Methods: The subjects consisted of 43 healthy young persons (20.33±0.47 years, 16 males, 27 females) and 38 elderly residents with independent activities of daily living (ADL) (78.34±7.67 years, 18 males, 20 females). Maximal isometric force, measured using a hand-held dynamometer, was expressed as force (N) divided by the body weight (N/kg), and compared between the young and elderly subjects. Furthermore, the elderly subjects’ value (older-to-young ratio (O-Y ratio)) was calculated establishing the mean muscle strength in the young subjects as a reference (100%). The characteristics of aging-related changes were also examined.Results: There were significant differences in muscle strength between the young and elderly subjects for ankle dorsiflexion, knee flexion/extension, hip flexion/extension, shoulder flexion/abduction/internal rotation/external rotation, and elbow flexion. The O-Y ratio for hip extension was the lowest, followed by shoulder external rotation, shoulder internal rotation, shoulder flexion, and hip flexion.Conclusions: Concerning aging-related muscle weakness, that of hip extension was particularly marked. To strengthen ADL motions/physical endurance, the understanding of muscle groups that decrease with aging may be important.