اثر حمل کوله‌پشتی با بارهای مختلف بر فعالیت الکترومایوگرافی منتخبی از عضلات اندام تحتانی حین راه رفتن در دانش آموزان مقطع ابتدایی شهرستان همدان

Background: The purpose of this study was to assess the effects of carrying backpack with different loads on electromyography activity of selected lower limb muscles and fatigue during walking in elementary school students. Methods: Fifteen 9 to 11 years elementary school students were selected through convenient sampling method.&nbsp; Subjects walked on the treadmill at a speed of 1.1 meters per second for 20 minutes while carrying backpacks under different conditions:&nbsp; no weight, 10, 15 and 20% of their body weight. While walking on the treadmill for twenty minutes, electromyography activity of rectus femoris, vastus medialis, vastus lateralis, biceps femoris, medialis gastrocnemius and tibialis anterior muscles were recorded for 10 seconds every five minutes (4 trials). Data were analyzed by ANOVA with repeated measures (p<0.05). Results: Electropmyography activity of rectus femoris, vastus medialis, vastus lateralis, biceps femoris and medialis gastrocnemius significantly increased with increasing backpack load, but no change was observed for tibialis anterior muscle activity. The median frequency of rectus femoris, vastus lateralis, biceps femoris and medialis gastrocnemius decreased with&nbsp; increasing backpack load, but no change&nbsp; was observed vastus medialis and tibialis anterior muscles. Conclusion: According to the results, it can be concluded that increasing muscles activity with increasing backpack load may lead to fatigue, consequently increase risk of injury during carrying school backpack.