The effect of common school bags on elementary school girl's trunk muscles electrical activity

the variety of the bags in the marhet, persudes students to use variable bags, irrespective of their muscle of physical complications. Researches show that various methods for educational devices carrying, have different effects on student physical pain perception and muscles, skeletal, cardio vascular, respiratory and metabolism performances. This research is conducted to review the school common bags carrying (hand bag, shoulder bag and backpack) on elementary school girl students body muscles electrical activity. this study is from semi-empirical kind. This research subjects are selected (one school randomly) from hamedan city elementary grade girl students. Their body muscles electrical activities include: spine erectro muscle(ES), rectus abdominis (RA), upper trapiziuse (UT) and pectoralise major(PM) bilateral are recorded for each student by using EMG unit after carrying each one of these bags that weight about 10 percent of their body weight for 15 minutes on treedmile with a speed of 1/1 m/s and one minute standing. Finding showed that shoulder bag carrying result in dissimilar activities of left and right parts of four ES, RA, UT, PM muscles.(p=0/001). Hand bag carrying results in increasing this dissimilarity in left and right parts of UT, RA, ES muscles (p=0/001), so that EMG activity level in RA, ES muscles opposite direction increased sighificantly (p=0/001) and it reduced significantly in the other direction(p=0/001). while in UT muscle significaticant increase in the other direction and reduction in the opposite direction is observed (p=0/001) left and right parts activity of PM muscle during handbag carrying is similar (p=0/068), during backpack carrying EMG activity of RA muscle is reduced in a significant and dissimilar way(p=0/001) and it reduces in a significant and similar way in PM, UT and ES muscles(p=0/001).so backpack is considered as the best schoolbag in comparison to the other reviewed bags because of similar activities and lower activities of right and left parts of the muscles.