The effects of childhood obesity on compressive tibiofemoral force and muscle functions during normal walking. (#205)
The prevalence of obesity among children has increased dramatically in the past few decades and excess body weight in childhood was found to be indicative of skeletal problems in later life. Since obeisty is a known risk factor for musculoskeletal pain and disorders, determining the joint loads and muscle activities may contribute to clarify the pathophysiologic role of obesity in the development and progression of joint problems (eg. knee osteoarthritis). The purpose of this study was to utilize musculoskeletal modelling and forward simulation to investigate the gait strategy of obese children at musculoskeletal level. We generated a 3D muscle-driven simulation of eight obese and eight normal-weight boys aged 10-12 years, walking at their self-selected speed. The compressive tibiofemoral force (CTF) and individual muscle contribution to the support and progression accelerations of centre of mass (COM) were computed for each participant based on the subject-specific musculoskeletal model. The results found a linear relationship between the self-selected speed and the weight-normalized peak CTF (R2 = 0.611). Even though obese children walked at a significantly slower speed, the absolute CTF was still 25% higher than normal weight children. The peak CTF as mainly caused by the activity of the quadriceps during stance phase. Obese children and non-obese children use similar muscles to support and accelerate body COM but non-obese children had significnatly greater magnitude of individual muscle contribution. Reduced walking speed is a main strategy used by obese children to decrease the joint load and muscle requirement. It suggested that self-selected speed walking should be more appropriate rather than fast walking as an exercise option for obese children. Although faster walking could consume more energy, it would increase the risk of musculoskeletal injury. Optimized mechanical efficiency and relatively lower joint loading allow obese individual exercise for longer time without fatigue and joint discomforts.
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