The Effect of a Vertical Load on Gluteus Medius Activity and Gait Characteristics during Walking

[Purpose] The present study examined the activity and the gait characteristics of thegluteus medius and the trunk stability muscles during the stance phase of gait on levelground when a vertical load corresponding to 0%, 1%, or 2% of body weight was placed onthe lower extremities during the swing phase of the gait. [Methods] The subjects were 40young males aged between 21 and 30 years. The vertical load, corresponding to 0%, 1%, 2%of weight, which was measured with an electronic scale, was placed bilaterally 3 cm abovefrom the upper part of the lateral malleous. Electrodes were symmetrically attached to thegluteus medius, erector spinae, external oblique, and internal oblique muscles. [Results]There were significant differences in the activities of the left gluteus medius, bilateralexternal oblique, and right internal oblique muscles among the vertical loads of 0%, 1%,and 2% during gait. [Conclusion] Increases in vertical load were accompanied by changes inthe activities of the internal and external oblique abdominal muscles to ensure thestability of the trunk under the different loads. Gait was only possible with the activityof the gluteus medius muscle and the trunk muscles resisting the different vertical loadsrather than activating other muscles of the lower extremities in terms of energyefficiency.Key words: Vertical load, Gait, Gluteus medius