Stress-Related Responses to Alternations between Repetitive Physical Work and Cognitive Tasks of Different Difficulties.

Susanna Mixter,Helena Jahncke,Eugene Lyskov,Svend Erik Mathiassen,David M Hallman,Kent Dimberg,Petra Lindfors

doi:10.3390/ijerph17228509

Abstract

Alternating between physical and cognitive tasks has been proposed as an alternative in job rotation, allowing workers to recover from the physical work while still being productive. However, effects of such alternations on stress have not been investigated. This controlled experiment aimed at determining the extent to which stress-related responses develop during alternating physical and cognitive work, and to determine the extent to which cognitive task (CT) difficulty influences these responses. Fifteen women performed three sessions of 10 consecutive work bouts each including a seven-minute repetitive physical task (pipetting) and a three-minute CT (n-back) at one of three difficulty levels. Stress was assessed in terms of changes in heart rate variability, blood pressure, salivary alpha-amylase, salivary cortisol, perceived stress, and cognitive performance. The work session did not result in any marked stress response, and CT difficulty did not significantly influence stress, apart from alpha-amylase being higher at the easiest CT (F = 5.34, p = 0.02). Thus, according to our results, alternating between repetitive physical tasks and cognitive tasks may be a feasible alternative to classic job rotation between physical tasks only, even if the cognitive task is quite difficult. Future studies should address possible effects of the temporal pattern of alternations, and combine even other occupationally relevant tasks, preferably for extended periods of time.

Highlights

Increased variation in biomechanical exposure has been proposed by authorities and researchers as a remedy for reducing risks of musculoskeletal disorders (MSD), in jobs dominated by repetitive and constrained tasks [1,2,3,4,5]
We found no critical violations of assumptions of normally distributed data, except for HF heart rate variability (HRV), which were log-transformed prior to further analysis
I.e., before performing any physical or cognitive task, we found no significant differences between the three conditions (CT1-3) in any outcome variable, except for blood pressure (BP)

Summary

Introduction

Increased variation in biomechanical exposure has been proposed by authorities and researchers as a remedy for reducing risks of musculoskeletal disorders (MSD), in jobs dominated by repetitive and constrained tasks [1,2,3,4,5]. Extending or restructuring rest breaks appears to have limited effect on fatigue and discomfort in occupational settings [9]. One explanation may be that rest allowances can be implemented only to a limited extent because breaks are essentially non-productive time [5,7]. Job rotation is another way of increasing physical variation, but studies so-far show inconclusive results regarding whether job rotation is, effective in increasing variation and reducing musculoskeletal complaints [10,11,12]. Public Health 2020, 17, 8509; doi:10.3390/ijerph17228509 www.mdpi.com/journal/ijerph

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