Abstract
Childhood obesity is associated with impaired physical fitness and increased future cardiometabolic risk. Aerobic capacity and muscular strength are key components of health-related fitness; however, their interrelationship across weight status remains underexplored in Middle Eastern pediatric populations. This study aimed to examine the association between aerobic capacity and muscular strength among obese and non-obese children aged 10–15 years in the Riyadh region, Kingdom of Saudi Arabia. A cross-sectional study was conducted among 200 children (52% boys and 48% girls) selected from screened government and private school students in Riyadh, comprising 100 obese and 100 non-obese participants for balanced group comparison. Obesity was defined using World Health Organization age- and sex-specific BMI percentiles. Aerobic capacity was assessed using the 20-m shuttle run test, with estimated VO2max calculated from performance. Muscular strength was measured using handgrip dynamometry, and relative strength was derived by normalizing grip strength to body weight. Group comparisons were performed using independent t-tests. Associations between aerobic capacity and muscular strength were analyzed using correlation and multivariable linear regression adjusting for age, sex, and BMI. Obese children demonstrated significantly lower shuttle run performance and estimated VO2max compared with non-obese children (p < 0.001). Absolute handgrip strength was higher in obese children (p = 0.01), whereas relative muscular strength was significantly lower (p < 0.001). Aerobic capacity showed moderate to strong positive correlations with both absolute and relative muscular strength in both groups, with stronger associations observed for relative strength. In multivariable regression analyses conducted using separate models to avoid mathematical coupling, relative muscular strength independently predicted VO2max after adjusting for age and sex (β = 0.47, p < 0.001), explaining 52% of variance. In a separate adiposity model, BMI was inversely associated with aerobic capacity (β = −0.51, p < 0.001), explaining 56% of variance. Obese children aged 10–15 years exhibited reduced aerobic capacity and lower relative muscular strength despite higher absolute strength. Both adiposity and functional muscular strength were independently associated with aerobic fitness when modeled separately. The stronger predictive value of relative muscular strength highlights the importance of improving strength relative to body mass, alongside aerobic conditioning, in pediatric obesity prevention and intervention programs.