Higher abdominal adiposity is associated with higher lean muscle mass but lower muscle quality in middle-aged and older men and women: the Framingham Heart Study.

BACKGROUND: The objective was to determine if abdominal fat is related to poor muscle health. METHODS: This cross-sectional study included 428 males and 534 females with appendicular lean mass (ALM, kg) from dual-energy X-ray absorptiometry (DXA), grip strength (kg), and upper extremity muscle "quality" (grip strength/arm lean mass) measured (1996-2001) in the Framingham Offspring Study. Sex-specific linear regressions associated adiposity measures [waist circumference (WC, cm) and visceral adipose tissue (VAT, cm3), and subcutaneous adipose tissue (SAT, cm3)] as Z-scores with each measure of muscle, adjusting for covariates. Models were further stratified by body mass index (BMI, < 30, ≥ 30 kg/m2). RESULTS: Mean (± SD) age was 60 ± 9 years and BMI was 28.9 ± 4.6 kg/m2 (men) and 27.7 ± 5.8 kg/m2, (women). In men, the BMI-stratified analyses showed higher WC was associated with higher ALM (P < 0.0001 each) but with lower muscle quality (P < 0.02) in both BMI groups. Higher SAT was also associated with higher ALM (P = 0.0002) and lower muscle quality (P = 0.0002) in men with BMI < 30, but not in obese men. In women, higher WC, SAT, and VAT were each associated with higher ALM but lower muscle quality, particularly in obese women. Higher SAT (P = 0.05) and VAT (P = 0.04) were associated with higher quadriceps strength in women with BMI < 30 kg/m2 but not in obese women. CONCLUSIONS: Higher abdominal fat may be associated with greater lean mass but poorer muscle quality, particularly in obese women. This suggests that adipose tissue may have endocrine influences on muscle, which should be confirmed in longitudinal studies.