The effects of posture and cognitive information processing from different sensory modalities on perceived musculoskeletal discomfort and work performance

It appears evident within the literature that many individuals are subjected to a double burden of both physical and mental demands at work (Garson, 2009; Szeto, 2009). Physical work exposures often include having to maintain awkward, static postures for sustained periods of time, which ultimately result in the onset of local muscle fatigue and accompanied symptoms of discomfort (Armstrong et al., 1993). It is suggested that symptoms of discomfort trigger the motivation to recover vital resources, depleted during work, through down-regulation or complete rest (Brandäo and Graeff, 2006).

Various authors, however, have reported that the distraction, offered by concurrent cognitive engagement causes perceptions of discomfort to be over-ridden (or attenuated) (Bushnell et al., 1985; Miron et al., 1989; Hodes et al., 1996; Bushnell et al, 1999; Bantick et al, 2002; Tracey et al., 2002; Seminowicz et al., 2004; Van Damme et al., 2008). Hence, individuals who have jobs that require high levels of concentration are more likely to suffer from long-term musculoskeletal injuries, on account of being unable to receive biofeedback regarding the appropriate timing of rest and recovery (Garson, 2009). In contrast, it has also been reported that intense symptoms of discomfort/pain disrupt cognitive processing, resulting in lowered work performance (Eccleston et al, 1999).
The authors aimed with this research was to investigate the influence of time, awkward posture, and cognitive processing (utilizing different senses; visual and auditory) on measured physical (heart rate (HR), heart rate variability (HRV), electromyography (EMG)), perceptual (body discomfort (BD)) and performance (% error and reading speed) responses.

Results indicated that, apart from the percentage of error incurred, the influence of modality had no significant effect on any of the measured responses, irrespective of time and posture assumed. Exposure to an awkward posture, designed to induce muscular discomfort, had a significant impact on measured HRV during the visual condition. The addition of a stooped posture caused a significant improvement in auditory performance, during the first two minutes. Apart from this unexpected finding, which can be explained by the order of permutation, induced muscular discomfort caused no significant decrements in performance. Performance and HRV remained relatively unaffected by the influence of time. However, perceptions of body discomfort (BD) increased significantly from minute two to four.

Hopley, B., & Mattison, M. (2013). The effects of posture and cognitive information processing from different sensory modalities on perceived musculoskeletal discomfort and work performance. Ergonomics SA, 25(2), 12-21.