The Effects of Schoolbag Style on Muscle Activation in Lower Extremities during Level Walking and Hill Walking in Primary School Students

It was necessary to have a schoolbag that was correct in size and style for the wearer and held the load against the trunk. Some studies investigated the effects of different bag styles on the spine, trunk muscles and gait parameters of children, but few on lower limbs muscles during hill walking were addressed. The purpose of this study was to compare the muscle activation of lower limbs muscles between different schoolbag styles (unloading, backpack & drag bag) during level walking and hill walking. Seven volunteers (2 male & 5 female; 10.3 ± 1.5 yrs; 133.3 ± 7.7 cm; 32.1 ± 6.8 kg) in Chiayi area participated in this study. All of them finished six situations (2 slopes × 3 schoolbag styles) through treadmill walking at 2 km/hr. The weight of schoolbag was set at 10% of body weight. The electromyography signals of subject’s left vastus lateralis, biceps femoris, tibials anterior and lateral head of gastrocnemius in stance phase was collected using surface electromyography system and foot switch sensors were placed on the toe and heel to divide the stance phase and swing phase in gait cycle. A two-way ANOVA with repeated measures was used to analyze the effects of different schoolbags on muscle activation during two walking situations. There was no statistical difference in iEMG between unloading, backpack, and drag bag style during level walking; however, there was significant difference in vastus lateralis during hill walking. When primary school students walk on flat surface, there was no significant difference in muscle activation in lower limbs regardless of the schoolbag style. Walking with backpack and drag bag significantly loads on lower extremity muscle activity during hill walking.