Human skeletal muscle-specific atrophy with aging: a comprehensive review

Area of Science:

• Gerontology
• Skeletal Muscle Physiology
• Aging Research

Background:

• Age-related skeletal muscle atrophy is a significant concern, impacting mobility and quality of life.
• Existing research often lacks muscle-specific detail, limiting targeted interventions.
• Understanding muscle group differences is crucial for addressing functional decline in aging populations.

Purpose of the Study:

• To provide a comprehensive, muscle-specific review of age-related skeletal muscle atrophy.
• To quantify the decline in size for various muscle groups over approximately 50 years of aging.
• To identify factors influencing muscle-specific atrophy rates.

Main Methods:

• Systematic review and meta-analysis of 47 cross-sectional studies.
• Inclusion of data from 982 young (approx. 25 yr) and 1,003 old (approx. 75 yr) individuals.
• Analysis of nine major muscle groups and subcomponent muscles within the hamstrings, quadriceps, and triceps surae.

Main Results:

• Significant muscle-specific atrophy rates were observed across nine muscle groups, ranging from -9% (dorsiflexors) to -29% (psoas) over ~50 years.
• Subcomponent analysis revealed substantial variation, with rectus femoris (-33%) showing the highest atrophy and soleus (-6%) the lowest.
• Muscle activity, fiber type, sex, and aging timeline appear to influence atrophy rates.

Conclusions:

• Age-related skeletal muscle atrophy is highly variable between different muscle groups.
• The significant range in atrophy rates underscores the need for muscle-specific research and interventions.
• Further investigation into unexamined muscles is essential for a complete understanding of aging-related functional deficits.