The effect of frequency on psychophysical responses to lifting.

Olivier, S.C.; Scott, P.A.

Abstract

One of the main goals of ergonomics is to establish task requirements in order to prevent injury. This is of particular importance in manual materials handling (MMH), as manual lifting represents a major cause of injury to workers and a significant cost to industry. In spite of the existence of established guidelines, there is evidence that the majority of injuries are caused by overexertion (Ayoub, 1992). In support of Oborne (1987), Charteris and Scott (1993) have argued that frequency is one of several task-related variables that have an influence on the demands of a lifting task. Clearly, all other factors being equal, as the pace of the work is increased, so the load should decrease. Utilising fifteen male volunteer subjects (average age 21.3 years), this study investigated psychophysical responses to a lifting task at three different frequencies - 5, 10 and 15 lifts per minute - with the total task duration being 15 minutes. Heart rate (HR) and Ratings of Perceived Exertion (RPE) data were recorded, and the tasks were analysed using LIFTRISK and NIOSH. There were significant differences between successive frequencies for all data recorded. As expected, HR and RPE increased with lifting frequency. There was no significant correlation between HR and RPE for any of the conditions. Correlations were, however, higher at low work intensities. RPE Central values were somewhat lower than Overall values; this finding seems to lend support to the contention that Central factors do not play as important a role in the perceptions of exertion as was originally thought (Pandolf, 1982; Olivier and Scott, 1993). In conclusion, this study investigated the effect of frequency on psychophysical responses for a task with inherent high-risk characteristics. As lift frequency increased, the correlation between HR and RPE decreased. With low subject numbers precluding a firm conclusion, this study tentatively proposes that caution should be exercised when using RPE in self-determination of task limitations for a MMH task.

Citation

OLIVIER, S.C. and SCOTT, P.A. 1994. The effect of frequency on psychophysical responses to lifting. Ergonomics SA, 6(1), pages 9-14.

• Journal Article Type: Article
• Acceptance Date: Oct 31, 1994
• Publication Date: Oct 31, 1994
• Deposit Date: Aug 16, 2022
• Publicly Available Date: Aug 16, 2022
• Journal: Ergonomics SA
• Print ISSN: 1010-2728
• Publisher: Ergonomics Society of South Africa
• Peer Reviewed: Peer Reviewed
• Volume: 6
• Issue: 1
• Pages: 9-14
• Keywords: Manual handling; Lifting; Physical exertion; Ratings of perceived exertion (RPE); Heart rate
• Public URL: https://rgu-repository.worktribe.com/output/1579623