Precision markedly attenuates repetitive lift capacity

Authors

Brooke R. Collier, University of WollongongFollow
Laura Holland, University of WollongongFollow
Deirdre McGhee, University of WollongongFollow
John Sampson, University of WollongongFollow
Alison Bell, University of WollongongFollow
Paul J. Stapley, University of WollongongFollow
Herbert Groeller, University of WollongongFollow

RIS ID

91718

Publication Details

Collier, B. R., Holland, L., McGhee, D., Sampson, J. A., Bell, A., Stapley, P. J. & Groeller, H. (2014). Precision markedly attenuates repetitive lift capacity. Ergonomics: an international journal of research and practice in human factors and ergonomics, 57 (9), 1427-1439.

Abstract

This study investigated the effect of precision on time to task failure in a repetitive whole-body manual handling task. Twelve participants were required to repetitively lift a box weighing 65% of their single repetition maximum to shoulder height using either precise or unconstrained box placement. Muscle activity, forces exerted at the ground, 2D body kinematics, box acceleration and psychophysical measures of performance were recorded until task failure was reached. With precision, time to task failure for repetitive lifting was reduced by 72%, whereas the duration taken to complete a single lift and anterior deltoid muscle activation increased by 39% and 25%, respectively. Yet, no significant difference was observed in ratings of perceived exertion or heart rate at task failure. In conclusion, our results suggest that when accuracy is a characteristic of a repetitive manual handling task, physical work capacity will decline markedly. Practitioner Summary: The capacity to lift repetitively to shoulder height was reduced by 72% when increased accuracy was required to place a box upon a shelf. Lifting strategy and muscle activity were also modified, confirming practitioners should take into consideration movement precision when evaluating the demands of repetitive manual handling tasks.