INFLUENCE OF BACKPACKS ON MYOELECTRICAL ACTIVITIES OF UPPER FIBERS OF TRAPEZIUS IN SCHOOL STUDENTS DURING WALKING

Abstract

Background: there is a growing concern of the effects of 'heavy' backpack on school student s' neck muscles activities which lead to muscle fatigue.The purposeof this study was to compare between normalized root mean square (RMS) of Electromyography (EMG) activities of upper fibers of Trapezius (UFT)(RT and LT) during walking carrying the modified double sided packwith that during walking carrying the ordinruy backpackin preparatory school students. Subjects: thirty school students with mean age of 13.66±1.32 years were assigned in one group. Materials and Methods: measurements of the normalized RMS of EMG of UFT (RT and LT) were recorded, for each student, under three conditions: First while carrying no pack (reference isometric voluntruy contraction), second while walking carrying the modified double sided pack for five min, third while walking carrying the ordinruy backpack for five min with rest . ten minutes after each test. Results: Duringwalking carrying the modified double sided pack, the normalized RMS ofEMG ofRT UFT was significantly less (Mean Rank 23.5 and median 1.113) thanduring walking carrying the ordinruy backpack (Mean Rank 37.5 andmedian 1.314 ). Duringwalking carrying the modified double sided pack, the normalized RMS of EMG of LT UFT was significantly less(Mean Rank 24 and median 1.055) than during walking carrying the ordinruy backpack (Mean Rank 37and median 1.53) with (Z value was -3.105 for RT UFT and Z- value was -2.883 for LT UFT and p<0.05).Discussion and Conclusion: themodified double sided pack significantly induced less normalized RMS of EMG activity ofUFT(RT and LT) compared with the ordinruy backpack style. Keywords: backpack,normalized RMS,students, upper fibers oftrapezius.