FOREARM MUSCULAR LOAD AND WRIST ANGLE AMONG AUTOMOBILE ASSEMBLY-LINE WORKERS IN RELATION TO SYMPTOMS

Electromyographic activity (EMG) from m. flexor carpi radialis (FCR) a nd m. extensor carpi radialis longus (ECRL) of the right forearm was r ecorded together with wrist angles in the flexion/extension and radial /ulnar plane in 20 healthy automobile assembly line workers during wor k. Eleven of these were randomly recruited from assembly stations with a low prevalence of subjective wrist/forearm symptoms (LPS), while th e rest came from stations with a high prevalence of symptoms (HPS). Th e main EMG finding was a clear difference in activation pattern betwee n flexors and extensors. ECRL was activated more statically, while FCR had a more dynamic pattern with more pauses but also higher peak load s, The main wrist angle finding was a difference in angle distribution as well as absolute angular velocity in the radial/ulnar plane betwee n LPS and HPS work stations. Workers in HPS stations worked longer tim es in a more ulnar deviated hand position and had higher absolute devi ation angular velocity compared to LPS workers, indicating ulnar devia tion as a risk factor. Generally, ulnar deviation from a neutral posit ion was more frequent than angular displacement in the flexion/extensi on plane. Copyright (C) 1996 Elsevier Science Ltd.