The Effect of Asymmetric Lower-Extremity Muscle Force of Elementary Students on Dynamic Balance during Walking

The purpose of this study was to evaluate the effect of asymmetric muscle force in lower extremity on dynamic balance during walking. Sixteen elementary students(age: 12.3 ± 0.7 yrs, height: 149.4 ± 9.7 cm, weight 40.6 ± 7.8 kg) who have no musculoskeletal disorder were recruited as the subjects. Temporal parameters, M-L inclination angle of XCoM-CoP, M-L and A-P CoP, loading rate, and decay rate were determined for each trial. For each dependent variable, a independent-sample t-test was performed to test if significant difference existed between each conditions(p<.05). The displacement of antero-posterior COP during RTO-LHC1 in SG was siginificantly smaller than corresponding value in AG. In contrast, the displacement of medio-lateral COP during RTO-LHC1 in SG was greater than those of AG. It seems that imbalance of muscle force may result in increasing the medio-lateral stance in order to minimize the instability. We found that the asymmetric muscle force in the lower extremity may be a reason for the awkward control of impact force.