Muscle quality. I. Age-associated differences between arm and leg muscle groups

Area of Science:

• Gerontology
• Muscle Physiology
• Biomedical Engineering

Background:

• Muscle quality (MQ) is a critical indicator of physical function and healthspan.
• Understanding age- and sex-related differences in MQ is essential for targeted interventions.
• Previous research has not comprehensively compared arm and leg MQ across the adult lifespan.

Purpose of the Study:

• To investigate the differences in arm and leg muscle quality (MQ) across the adult lifespan in men and women.
• To analyze how concentric (Con) and eccentric (Ecc) peak torque (PT) and appendicular skeletal muscle mass (MM) contribute to these differences.
• To determine the influence of age and gender on MQ in different muscle groups.

Main Methods:

• Measured Con and Ecc peak torque (PT) in 703 adults (19-93 years).
• Determined appendicular skeletal muscle mass (MM) in arm and leg for 502 subjects.
• Utilized regression analysis to define and compare muscle quality (MQ = PT/MM) across groups.

Main Results:

• Arm MQ was significantly higher (~30%) than leg MQ in both genders.
• In men, arm and leg MQ declined similarly with age.
• In women, leg MQ declined ~20% more than arm MQ with age; arm MQ decline was steeper in men than women.

Conclusions:

• Muscle quality is significantly influenced by age and gender.
• The impact of aging and sex on MQ varies depending on the muscle group (arm vs. leg) and the type of muscle action (concentric vs. eccentric).
• These findings highlight the need for sex- and muscle-group-specific considerations in assessing and maintaining muscle health throughout life.