Mixed
Cross-sectional analysis of aging populations reveals a significant decline in muscle quality (strength per unit muscle mass) when muscle mass is estimated via anthropometric cross-sectional area (CSA) or DXA-derived fat-free mass (FFM), but not when estimated via 24-hour urinary creatinine excretion (CREAT).
When assessing muscle health in older adults, relying solely on limb circumference (CSA) may overestimate the decline in muscle quality compared to biochemical markers like creatinine excretion. If using circumference, expect a steeper apparent decline in efficiency (strength per kg) with age than if using more comprehensive mass estimates.
Muscle quality declined in both arm and leg with age in cross-sectional analyses using CSA and FFM, but not CREAT.
Why this rating
Large sample sizes (N=617 for arms, N=675 for legs) and rigorous longitudinal follow-up (up to 25 years) in the Baltimore Longitudinal Study of Aging.
Source
Muscle Quality and Age: Cross-Sectional and Longitudinal Comparisons
E. Jeffrey Metter et al. · The Journals of Gerontology Series A · 1999
DOI 10.1093/gerona/54.5.b207
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