Do fitness and fatigue affect gait biomechanics in overweight and obese children?

- Obese children tend to have higher hip and knee joint moments during walking.
- Aerobic fitness has a moderately strong inverse relationship with joint moments.
- Cardiorespiratory fatigue also escalates joint moments during walking gait.
- Obese children should be advised for exercise with regards to fitness and fatigue.

The purpose of this study was to determine how an overweight or obese child's cardiorespiratory fitness level and a state of fatigue affect gait biomechanics.MethodsUsing a three-dimensional motion analysis system, twenty-nine (female and male) overweight and obese children aged 8-11 years walked on force plates before and after being fatigued from the Progressive Aerobic Cardiovascular Endurance Run (PACER) protocol. Joint moments were calculated for the knee and hip in the frontal and sagittal planes.ResultsIn a non-fatigued state, peak hip and knee adductor moments showed a negative relationship with cardiorespiratory fitness level (R2 = 0.26, 0.26). After the subjects were fatigued, peak hip extensor (p = 0.02), peak knee extensor moments (p = 0.02) and peak knee adductor moments (p = 0.01) showed a significant increase.ConclusionThis trend illustrates that as an overweight or obese individual's fitness improves, the lower limb joint moments in the frontal plane decrease when walking. However, with the introduction of cardiorespiratory fatigue, lower limb joint moments tend to increase in the frontal and sagittal planes. Increased joint stress may have potential implications for obese children performing physical activity, as well as for clinicians who are attempting to intervene in the cycle of obesity.