# Associations of physical activity with phase angle in adolescents living with HIV: The moderating and mediating roles of physical fitness

## TL;DR

Physical activity is linked to better cellular health in HIV-positive adolescents, with physical fitness factors like muscle strength and body composition playing a role in this relationship.

## Contribution

The study identifies that muscular strength and body composition partially moderate the relationship between physical activity and phase angle in adolescents with HIV.

## Key findings

- Physical activity is positively associated with phase angle in adolescents with HIV, independent of confounders.
- Muscular strength significantly moderates the relationship between physical activity and phase angle.
- Aerobic capacity and body composition also partially moderate this relationship.

## Abstract

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). VO2 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.

The graphical abstract illustrates the association between physical activity levels and cellular health in adolescents living with HIV (ALHIV). Cellular health was assessed using phase angle (PhA), derived from bioelectrical impedance analysis, a marker of cell membrane integrity and body cell mass. Higher physical activity levels were positively associated with PhA, independent of age, sex, viral load, and antiretroviral therapy (ART). Although mediation models were not supported, aerobic fitness (VO2 peak) and body fat percentage partially moderated this relationship, indicating that the magnitude of the association varied according to physical fitness and body composition. A high prevalence of physical inactivity and inadequate PhA values was observed, underscoring the vulnerability of this population and supporting the relevance of physical activity and body composition management as components of care for adolescents living with HIV.