Skeletal muscle mass and distribution in 468 men and women aged 18-88 yr.
Level 4 - case-series / case-control
Cross-sectional observational study without longitudinal follow-up.
PubMed 10904038 · doi:10.1152/jappl.2000.89.1.81
What was done
Whole-body magnetic resonance imaging (MRI) was used to assess skeletal muscle (SM) mass and anatomical distribution across 468 men and women aged 18 to 88 years. Investigators analyzed the effects of age, gender, body weight, and height on total and regional muscle mass.
What was found
Men had significantly more SM than women in absolute mass (33.0 vs. 21.0 kg, P < 0.001) and relative to body mass (38.4 vs. 30.6%, P < 0.001). Gender differences were larger in the upper body (40%) compared to the lower body (33%, P < 0.01). Relative SM mass decreased beginning in the third decade, while absolute SM mass decreases were observed after the fifth decade, largely driven by lower body SM loss. Height and weight explained ~50% of the variance in SM mass.
Why it matters
It establishes reference-standard MRI normative data across the adult lifespan, showing that age-related absolute muscle loss manifests predominantly in the lower limbs after age 50.
Limits
The cross-sectional design cannot directly establish individual longitudinal trajectories. The abstract does not report physical activity, race/ethnicity, health comorbidities, or functional strength outcomes.
Cited by
- partial From the age of 30 onwards, adults lose approximately 0.5% to 1% of muscle mass per year.