Effects of Postures and Wearing Night Vision Goggle on EMG Activities in Upper Neck and Trapezius
The purpose of present study was to examine the effects of postures and wearing night vision goggle on EMG activities. The EMG activities were measured in muscle groups of upper neck and trapezius while wearing two types of night vision goggle with three postures (stand, sit, and prone). Twenty-nine male infantry soldiers participated in the experiments after providing informed consents with respect to the investigative procedures. Two types of night visual goggle for binocular eyepiece with single image intensifier have been evaluated. The weight of night visual goggles for Type A and Type B are 608g and 560g, respectively. The EMG activity was recorded over the right side of the upper neck (level C2) and trapezius muscles. Results of ANOVA showed that the EMG activities of upper neck muscles were lower significantly while wearing Type B NVG. The RVC of upper neck muscles for Type A and Type B are 31% and 27%, respectively. Further various operating positions were significant difference in both muscle groups. There was the heavy workload in neck muscle groups (42.5% RVC) while wearing night visual goggle in prone position particularly. In addition, head-worn equipment increases the mechanical load on the neck and alters the center of mass forward and upward in relation to the motion axis in the neck and cervical spine. Thus, suggestions of present study provided that soldiers should be avoided wearing NVG in prone posture. The weight arrangement of NVG could be evaluated in further research.
KeywordsRepetitive Stress Injuries Occupational and Work Safety head-mounted equipment
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