Affiliations: [a] Edward P. Fitts Department of Industrial Engineering, North Carolina State University, Raleigh, NC, USA
| [b] Engineering Innovation Institute, University of Florida, Gainesville, FL, USA
| [c] Dataminr Inc., New York, NY, USA
| [d] Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
| [e] Department of Industrial and Systems Engineering, University of Florida, Gainesville, FL, USA
Correspondence:
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Address for correspondence: David B. Kaber, PhD, CHFP, CSP Dean’s Leadership Professor and Chair University of Florida, Herbert Wertheim Professor and Chair, Department of Industrial & Systems Engineering, 303 Weil Hall/P.O. Box 116595, Gainesville, FL 32611, USA. Tel.: +1 352 294 7700; Fax: +1 352 392 3537; E-mail: [email protected].
Abstract: BACKGROUND:Previously, a stretching regimen was designed for manual material handling (MMH) of gas cylinders as a potential ergonomic solution for reducing occupational injury. No studies have made use of objective process measures, such as muscle activation levels, for evaluation of effects of stretching programs. OBJECTIVE:Examine acute effects of stretching on muscle activation levels and driver perceived level of exertion in gas cylinder handling during simulated delivery operations. METHODS:A within-subject experiment was conducted with eight male participants being subjected randomly to two conditions over a two-day period: stretching before delivery trials and no stretching. Surface electromyography and the Borg CR-10 scale for perceived exertion were used. RESULTS:Generally, results were variable among muscle responses. The extensor muscle bundle in the forearm was found to show a significant decrease (p = 0.0464) in activation level because of stretching. The anterior deltoid and trapezius significantly increased (p < .0001) the EMG activation level with stretching. Also counter to expectations, participants rated perceived exertion significantly higher (p = 0.0423) for trials preceded by stretching. CONCLUSIONS:This research indicates a muscle stretching regimen in advance of MMH activities has mixed effects on activation levels across muscles. It is possible that effects are attributable to body posture positions, or manner of muscle use, during actual work activities. Findings indicate that stretching prior to work activity does have an impact on specific muscle activation.
Keywords: Surface electromyography, stretching program, manual material handling
