Lean Mass And Strength, Not Fat, Correlate Highly With Vascular Function In Midlife, African Americans

Abstract

PURPOSE: A critical need exists for investigation of modifiable risk factors within the midlife, African American population, so that future interventions may be more effective. Therefore, our purpose was to determine the relationship among measures of body composition, muscular strength, and peripheral vascular function in midlife, African Americans. METHODS: Twelve, midlife (60 ± 4 yr) African Americans (3 males, 9 females; +50% presenting at least 1 copy of the APOE4 gene) completed two visits consisting of peripheral vascular function, body composition, and muscular strength assessment. Forearm blood flow (FBF) was used to define vascular function with procedures of venous occlusion plethysmography (VOP) and reactive hyperemia (RH). This permitted the determination of resting FBF as well as peak flow and total hyperemia following transient ischemia. A DEXA scan was used to quantify body composition. The strength of each participant was estimated by performing a 5-repetition maximum (5RM) on a leg extension device. The VOP and RH procedures were performed during each visit (test-retest reliability), whereas the DEXA and 5RM were performed once during separate visits. The 2,1 model for intraclass coefficients (ICC) was used to calculate reliability. Pearson’s correlations were used to examine relationships among the vascular function, strength, and body composition. RESULTS: There was suitable reliability as well as no systemic error detected for resting FBF (ICC=0.425; p=0.242), peak FBF (ICC=0.945; p=0.479), and total hyperemia (ICC=0.707; p=0.607). Strong correlations were identified such as relationships between lean mass and peak FBF (r=0.771; p<0.001), total hyperemia FBF (r=0.894; p<0.001), as well as muscular strength FBF (r=0.849; p<0.001). Muscular strength exhibited a significant relationship with peak FBF (r=0.761; p=0.004) and total hyperemia (r=0.887; p<0.001). There were, however, no significant relationships among fat mass and the measures of peripheral vascular function (peak FBF [r=-0.309; p=0.328] and total hyperemia FBF [r=-0.120; p=0.711]). CONCLUSIONS: These findings suggest that interventions should consider promoting increases in lean mass and muscular strength as opposed to targeting fat reduction, if improving vascular function is the main objective.