An industrial assembly task known to imply a high risk for shoulder-neck disorders was simulated in the laboratory.
Eight females (aged 22-32 years) were trained to manage industrial work pace (120 according to the methods-time measurement system, MTM).
They carried out seven work protocols at different days with different combinations of work pace (120 or 100 MTM), break allowance (20 min of active or passive breaks added every 2 h), and duration of the working day (2,4 or 6 h).
During 6 h of work at 120 MTM the electromyographic (EMG) amplitude from the upper trapezius muscle increased by about 11%, the EMG zero crossing rate decreased by about 2.5%, and perceived fatigue increased by about 4 CR10 scale units.
When work pace was reduced to 100 MTM, the upper trapezius EMG amplitude decreased by 20% and became less variable.
Heart rate decreased by about 10 bpm, perceived fatigue decreased by about 1 CR10 scale units, and shoulder tenderness was reduced by about 5%. However, the work task could still not be performed in a physiological steady state.
Added breaks, whether active or passive, had no apparent effects on upper trapezius load during work or on physiological responses.
Recovery of EMG, maximal strength, heart rate and blood pressure sensitivity, and tenderness was complete 4 h after work, independent of the preceding work conditions.
These findings suggest that a limitation of the daily duration of assembly work may be more effective in limiting...
Mots-clés Pascal : Ergonomie, Travail à la chaîne, Simulation, Durée travail, Vitesse, Système ostéoarticulaire pathologie, Epaule, Cou, Homme, Physiologie travail, Electromyographie, Fatigue, Condition travail, Douleur, Médecine travail, Pause
Mots-clés Pascal anglais : Ergonomics, Assembly line work, Simulation, Work period, Velocity, Diseases of the osteoarticular system, Shoulder, Neck, Human, Occupational physiology, Electromyography, Fatigue, Working condition, Pain, Occupational medicine
Notice produite par :
Inist-CNRS - Institut de l'Information Scientifique et Technique
Cote : 96-0097686
Code Inist : 002B29C01. Création : 199608.