Horizontal lifting— Physiological and psychological responses

Five healthy brewer's draymen with 4-10 years of occupational experience were studied in the laboratory during horizontal lifting work, which simulated an order filling task at a brewery. The subjects performed lifting from left to right and were instructed to choose the weight of a case which they preferred for normal 8-hour piece-rate work. The subjects chose about half as heavy a case as in previous studies of vertical lifting. They also showed a great interindividual variation in the choice of the weight (6-17 kg), although intraindividual variation was slight. When the lifting rate was doubled, the average weight chosen was only lower by 11%, although the subjects performed 74% more work. Physiological measurements and ratings of perceived workload were made with 67, 100, 133, 167 and 200% of the individually preferred weights. Heart rate increased with increased case weight, but remained below l00 beats/min. Oxygen uptake and pulmonary ventilation also rose with increased case weight and lifting rat...