title: Forearm muscular load and wrist angle among automobile assembly line workers in relation to symptoms.
abstract: Electromyographic activity (EMG) from m. flexor carpi radialis (FCR) and m. extensor carpi radialis longus (ECRL) of the right forearm was recorded together with wrist angles in the flexion/extension and radial/ulnar plane in 20 healthy automobile assembly line workers during work. Eleven of these were randomly recruited from assembly stations with a low prevalence of subjective wrist/forearm symptoms (LPS), while the rest came from stations with a high prevalence of symptoms (HPS). The main EMG finding was a clear difference in activation pattern between flexors and extensors. ECRL was activated more statically, while FCR had a more dynamic pattern with more pauses but also higher peak loads. The main wrist angle finding was a difference in angle distribution as well as absolute angular velocity in the radial/ulnar plane between LPS and HPS work stations. Workers in HPS stations worked longer times in a more ulnar deviated hand position and had higher absolute deviation angular velocity compared to LPS workers, indicating ulnar deviation as a risk factor. Generally, ulnar deviation from a neutral position was more frequent than angular displacement in the flexion/extension plane.
authors.affiliation: Department of Ergonomics, National Institute for Working Life, Solna, Sweden.
authors.forename: G M
authors.initials: GM
authors.lastname: Hägg
authors.forename: J
authors.initials: J
authors.lastname: Oster
authors.forename: S
authors.initials: S
authors.lastname: Byström
mesh_terms: D000328:Adult; D001336:Automobiles; D001696:Biomechanical Phenomena; D004576:Electromyography; D005260:Female; D005542:Forearm / Q000502:physiology*; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D016272:Occupational Health; D014955:Wrist Joint / Q000502:physiology*