Presenter: Yu Shu
Advisor(s): Gary A. Mirka
Author(s): Yu Shu and Gary A. Mirka
Graduate Program: Industrial Engineering

Title: Effects of Wrist Splint Orthoses on Forearm Muscle Activity and Upper Extremity Kinematics

Abstract: Wrist splint orthoses (WSO) are ubiquitous in industrial environments but the literature as to their biomechanical effects is limited. This research studied the impact of wearing WSO on the electromyographic (EMG) of forearm muscles at varied deviated wrist postures and the kinematics of upper extremities at varied working surface angles. Ten subjects performed two experimental tasks. In the first task, the subject performed a series of simple, single-plane wrist exertions at varied wrist angles with and without WSO. EMG activity of three forearm muscles was recorded. In the second task, shoulder and trunk kinematics were recorded as the subject performed a computer jumper installation task at varied work surface angles with and without WSO. The results of EMG study revealed a strong interaction (p<0.05) between wrist angle and wearing WSO. At neutral wrist posture, wearing WSO did not increase normalized EMG of flexor carpi radialis (FCR). At 48 wrist flexion, wearing WSO increased the normalized EMG of FCR to 600% as compared to bare hand. These results indicated wearing WSO will increasing exposure to another risk factor- heavy load - at extreme wrist exertions. Wearing WSO also increased shoulder abduction angles significantly (average increase of 34.7%, p<0.01) during the jumper task indicating increased risk of musculoskeletal disorders to other body regions. The application of WSO should be carefully considered based on the new information provided in this study.