The Effects of Co-ordinating Postures With Shoulder and Elbow Flexion Angles on Maximum Grip Strength and Upper-Limb Muscle Activity in Standing and Sitting Postures

Eighteen co-ordination postures with shoulder flexion angles (0 degrees, 45 degrees and 90 degrees) and elbow flexion angles (0 degrees, 45 degrees and 90 degrees) in standing and sitting positions were evaluated to identify the effects of co-ordination postures on maximum grip strength and muscle activities of the upper limb in this study. Thirty-nine subjects were recruited and their maximum grip strengths were measured. According to the analysis of grip strength, grip strength was shown to be stronger in a standing posture (297.4 N) than in a sitting posture (274.6 N). In addition, grip strength (293.8 N) at 9 degrees shoulder flexion angle was significantly higher than that at 0 degrees and 45 degrees shoulder angles. There was no statistically significant difference in grip strength from the effects of elbow angles in this study. The results of muscle activities for all muscle groups showed a similar trend with the results of grip strength associated with shoulder angles.