Adiposity attenuates muscle quality and the adaptive response to resistance exercise in non-obese, healthy adults.

BACKGROUND: Emerging data have revealed a negative association between adiposity and muscle quality (MQ). There is a lack of research to examine this interaction among young, healthy individuals, and to evaluate the contribution of adiposity to adaptation after resistance exercise (RE).
OBJECTIVE: The purpose of this investigation was to examine the influence of subcutaneous adipose tissue (SAT) on muscle function among non-obese individuals before and after RE.
DESIGN: Analyses included 634 non-obese (body mass index <30 kg m(-2)) subjects (253 males, 381 females; age=23.3 ± 5.2 years). SAT and muscle mass (magnetic resonance imaging-derived SAT and biceps muscle volume), isometric and dynamic biceps strength, and MQ (strength/muscle volume), were analyzed at baseline and after 12 weeks of unilateral RE.
RESULTS: At baseline, SAT was independently associated with lower MQ for males (β=-0.55; P<0.01) and females (β=-0.45; P<0.01), controlling for body mass and age. Adaptation to RE revealed a significant negative association between SAT and changes for strength capacity (β=-0.13; p=0.03) and MQ (β=-0.14; P<0.01) among males. No attenuation was identified among females. Post-intervention SAT remained a negative predictor of MQ for males and females (β=-0.47; P<0.01).
CONCLUSIONS: The findings reveal that SAT is a negative predictor of MQ among non-obese, healthy adults, and that after 12 weeks of progressive RE this association was not ameliorated. Data suggest that SAT exerts a weak, negative influence on the adaptive response to strength and MQ among males.