A Canadian study of healthy adults showed that leg and arm lean body mass (LBM) independently associate with internal cardiac dimensions, ventricular relaxation, and systemic vascular resistance in a sex-specific manner, predominantly in women. The study included 70 white women and men matched by age (60±12 vs 58±15 years), physical activity, and cardiovascular risk factors. Regional (legs, arms, and trunk) and whole-body (total) body composition were assessed via dual-energy x-ray absorptiometry. Cardiac structure, function, and central/peripheral hemodynamics were measured via transthoracic echocardiography and the volume-clamp method at rest and peak incremental exercise. Regression analyses were used to assess sex-specific relationships between LBM and cardiovascular variables. Regional and total LBM were lower in women than men, with little overlap between sexes. Leg and arm LBM positively associated with left ventricular (LV) internal resting dimensions in women (r≥0.53, P≤0.002) but not men (P≥0.156). Leg, arm, and total LBM only associated with LV relaxation in women (r≥0.43, P≤0.013). All LBM variables strongly associated with LV volumes at peak exercise in women (r≥0.54, P≤0.001) but not men and negatively associated with total peripheral resistance at peak exercise in women (r≥0.43, P≤0.023). Adjustment by adiposity-related or cardiovascular risk factors did not alter results. The findings suggest a sex dimorphism in the regulation of the circulatory system. LBM is the fat-free mass, in which the predominant tissue is skeletal muscle. The extensive and sex-specific impact of body fat on health has been firmly established. Source: https://www.science.org/
