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Effect of aging on human adductor pollicis muscle function
M V Narici1, M Bordini, P Cerretelli
1Istituto di Tecnologie Biomediche Avanzate, Consiglio Nationale delle Ricerche, Milan, Italy.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|October 1, 1991
Summary
Aging significantly weakens and slows human adductor pollicis muscle function, with reduced force and relaxation rates observed after age 59. Paradoxically, older muscles show increased resistance to static fatigue.
Area of Science:
- Physiology
- Gerontology
- Muscle Biology
Background:
- Aging affects skeletal muscle contractile properties.
- Understanding age-related changes in muscle function is crucial for health and rehabilitation.
Purpose of the Study:
- To investigate the impact of aging on the voluntary and electrically evoked contractile properties of the human adductor pollicis muscle.
- To quantify age-related declines in muscle force, relaxation, and endurance.
Main Methods:
- Studied 70 healthy males aged 20-91 years, with 10 subjects per decade.
- Measured maximum isometric voluntary force and electrically evoked contractions.
- Assessed frequency-force relationships and isometric endurance during sustained stimulation.
Main Results:
- Maximum voluntary force declined significantly after age 59, reaching 57.6% of the second decade level by the eighth decade.
- A significant leftward shift in the frequency-force curve was noted in subjects over 80 years.
- Maximum relaxation rate decreased by 48.7% from the second to the eighth decade, with significant declines starting by the sixth decade.
- Isometric endurance showed a linear increase with age.
Conclusions:
- Aged adductor pollicis muscle exhibits reduced strength and speed (lower force, slower relaxation, lower fusion frequencies).
- Despite functional declines, older muscles demonstrate enhanced resistance to static fatigue.
- These findings highlight complex, paradoxical adaptations in muscle function with advancing age.