Using visual aids to influence manual lifting techniques: acute effects of viewing static images on spine motion

Abstract

Purpose. This study aimed to determine whether untrained observers alter their spine as directed via static images of different lifting techniques. Methods. Ten men and eight women, who had no lifting or visual observation training, performed box lifts. Following a self-selected lifting technique trial, participants performed four experimental lifting trials (in randomized order) wherein they were instructed to execute lifts in accordance with the techniques pictured. These techniques differed by the amount of knee, trunk and spine flexion modeled. Peak lumbar flexion angles and flexion/extension velocities were quantified, and then statistically analyzed via general linear models with two within-participant factors (condition = technique; phase = lift/lower). Results. Lumbar flexion angles and flexion/extension velocities differed between conditions (p < 0.001), although the effects depended on the combination of postural characteristics pictured. A main effect of phase was observed for peak lumbar flexion velocity only (p = 0.001). No condition × phase interaction effects were detected for any dependent variables (p > 0.050). Conclusions. Acute changes in lifting mechanics can be elicited via visual observation of pictured techniques. However, if using pictures to attenuate peak lumbar flexion displacements and velocities when lifting, auxiliary instruction may be needed to direct observers’ attention to the spine curvature displayed.

Keywords:

• observational learning
• lower back disorders
• movement (re)training
• back school
• manual materials handling

Acknowledgements

The authors thank the Centre of Research Expertise for the Prevention of Musculoskeletal Disorders and the University of Toronto’s Faculty of Kinesiology and Physical Education for funding for this study. The authors would also like to thank Dr Luc Tremblay and Malinda Hapuarachchi for their comments on an early draft of the study proposal.

Disclosure statement

No potential conflict of interest was reported by the authors.