Affiliations: [a] School of Human Kinetics and Recreation, Memorial University, Newfoundland and Labrador, Canada | [b] Faculty of Kinesiology, University of New Brunswick, New Brunswick, Canada
Correspondence:
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Address for correspondence: Scott N. MacKinnon, School of Human Kinetics and Recreation, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada A1C 5S7. Tel.: +1 709 864 6936; E-mail: smackinn@mun.ca
Abstract: The purpose of this study was to examine the biomechanical demands associated with MMH performed in moving environments. Twelve healthy male subjects performed four different lifting tasks (referred to as 10U, 15U, Close25 and Far25) while exposed to a simulated ship motion profile. Dependent measures included electromyographic (EMG) signals from several trunk muscles and thoracolumbar motions collected via a Lumbar Motion Monitor (LMM). A repeated measures ANOVA was employed to examine the differences between thoracolumbar velocities and trunk EMG activities between successful lifts and lifts during which a motion induced interruption (MII) was identified. The maximum EMG signals increased as MII events occurred for the left and right erector spinae and external obliques. The 10U lifting task significantly differed from both the Close25 and Far25 lifting tasks in the maximum left trapezius and the 10U lifting task differed from all other lifting tasks for the maximum right trapezius activities. There were increases in the maximum thoracolumbar velocities in the lateral bending and twisting planes for lifts incurring a MII across all lifting conditions when comparing successful lifts. These data suggest that performing tasks in moving environments will place an operator at an increased risk for musculoskeletal injuries, particularly when the rate of MII is high.
