The relation between physical activity, fitness, and fatness in adolescents: A mediation analysis.
Objectives To investigate the total, direct and mediated (by fatness) association of physical activity (PA) with fitness. Methods Body fat percentage (%Fat), maximal oxygen uptake (VO2max) and PA were measured directly in 18-year-olds (n=202) and their association analyzed with a linear regression-based mediation analysis after controlling for sex. Results The total association between PA and VO2max was significant (c=0.66, P<0.001) and was significantly mediated by %Fat (ab=0.25, 95% CI: 0.04–0.49). The direct association was also significant (c=0.41, P<0.001). Conclusion Physical activity is associated with VO2max in 18-year-old adolescents but a little over a third of that association is mediated by %Fat. Regardless of fatness, PA is important for fitness in this age group. Am. J. Hum. Biol., 2015.© 2015 Wiley Periodicals, Inc.