The effects of adiposity, muscular strength, cardiorespiratory fitness, and fatigue on gait biomechanics in overweight and obese children.

Abstract

Obesity rates continue to increase in the child population. Muscular strength, cardiorespiratory fitness, and fatigue can potentially affect joint stresses in obese children. The purposes are to examine: (1) the relationship between cardiorespiratory fitness and the change in joint stress pre- to post-fatigue; (2) the predictive value of fitness, adiposity, and muscular strength on joint stresses in fatigued and non-fatigued states; and, (3) the relationships between % body fat from skinfold and air displacement plethysmography. Twenty-seven children, with body mass index above the 85th percentile for their age participated in this study. Lower limb joint moments were recorded before and after a fatiguing Progressive Aerobic Cardiovascular Endurance Run protocol. Linear regression was used to assess the relationship between (1) fitness and change in joint stress pre- to post-fatigue, and (2) measures of %body fat using skinfold and plethysmography. Furthermore, Bland-Altman analysis quantified the agreement between measured adiposity using the two methods. The strongest relationship was observed between fitness and the change in the knee extensor moment pre- to post-fatigue (R² = 0.24). Regardless of fatigue state, adiposity and strength were identified as the strongest predictors of joint moments. Skinfold estimates were moderately predictive (R² = 0.56) of %body fat from air displacement plethysmography, and these two measures demonstrated instrument agreement with no proportional bias. Fitness level is not related to changes in biomechanics pre- to post-fatigue in overweight and obese children. Adiposity and lower extremity strength most strongly influenced joint moments in the frontal and sagittal planes.