Laboratory evaluation of belt usage with apple buckets

Background: Migrant and seasonal orchard harvest workers experience musculoskeletal strain caused by carrying heavy loads and holding awkward postures. An ergonomic hip belt designed to redistribute weight from the upper back, neck, and shoulders to the hips was evaluated. Methods: A comparison of muscle exertion (using electromyography [EMG]) of four key back and shoulder muscles and shoulder surface pressure (using a surface pressure sensor [PS]) was made among 10 laboratory volunteers under intervention and control conditions, in two postures (standing erect [0°]) and flexed [45°]). Results: All but one measure showed a significant reduction in the flexed posture with the intervention. Two of eight measures showed a significant reduction in the erect posture. Correlations with shoulder discomfort were found for deep shoulder EMG (r = 0.71, P = 0.021) and shoulder surface pressure (r = 0.58, P = 0.082). Conclusions: The hip belt intervention produces significant reductions in muscle activity while in a posture commonly assumed during orchard work.