Affiliations: [a] Human Performance Laboratory, Faculty of Kinesiology, University of New Brunswick, Fredericton, NB, Canada | [b] SafetyNet, Memorial University of Newfoundland, St. John's, NL, Canada | [c] School of Human Kinetics and Recreation, Memorial University of Newfoundland, St. John's, NL, Canada
Correspondence:
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Address for correspondence: Scott N. MacKinnon, SafetyNet, Memorial University of Newfoundland, St. John's, NL, Canada, A1C 5S7. Tel.: +1 709 737 7249; E-mail: smackinn@mun.ca
Abstract: The purpose of this study was to examine the effect of simulated vessel motions and load stabilities on thoracolumbar kinematics and foot centre of pressures (CoP) kinematics during the execution of common manual material handling (MMH) tasks. Nine male subjects completed a standing, holding and lifting task in three different simulator motion conditions (no motion, pitch and roll) while handling both a stable and unstable load (15 kg). Stability of load did not affect thoracolumbar kinematics, CoP or occurrence of motion induced interruptions (MIIs) while lifting or holding a load in any of the motion environments. Although no differences in thoracolumbar kinematics and CoP during the dynamic lifting task between baseline and either pitch or roll conditions were found, total anterior-posterior CoP displacements and thoracolumbar velocities were greater during motion conditions for stationary holding and standing tasks. MIIs occurred more often during the standing task than the lifting tasks. These results suggest that the rate of MII occurrence may be a function of the dynamic nature of the MMH task being performed. Tasks which restrain the movement of the individual may prevent the body from making adequate adaptations when stability is disturbed, increasing the likelihood for change-in-support strategies, potential for loss of balance and resultant injury.
Keywords: Postural stability, thoracolumbar kinematics, centre of pressure, motion induced interruptions
