Associations of physical activity with phase angle in adolescents living with <scp>HIV</scp> : The moderating and mediating roles of physical fitness

HIV infection and combination antiretroviral therapy (cART) can cause metabolic and cardiovascular changes in adolescents, who often have low physical activity (PA), harming their health. To investigate the relationship between PA levels and phase angle (PhA), we analyze potential moderating and mediating effects. Cross-sectional study with 47 adolescents (10-18 years) with vertically transmitted HIV. PA was assessed using PAQ-C; PhA was measured by tetrapolar bioelectrical impedance. Aerobic capacity was assessed by a submaximal bench step test, muscular strength by handgrip test, and body composition by anthropometric measures (arm muscle area [AMA] and body fat percentage [%BF]). Correlation, regression, and mediation and moderation analyses were performed. 61.7% showed inadequate PhA (<5.0°), mostly girls. A significant correlation existed between PA and PhA (r = 0.39; p = 0.01), maintained in adjusted regressions (β = 1.087; p = 0.001). General mediation and moderation effects were not confirmed; however, conditional analyses revealed high muscular strength significantly moderated the PA-PhA link (β = 1.0537; p = 0.0024). VO_{2 peak}, %BF, and AMA showed significant conditional effects at different levels. PA and PhA are directly associated, independent of confounders, and muscular strength, aerobic capacity, and body composition partially moderate this relation in adolescents with HIV.