Impact of Anterior Load Carriage on Muscle Fatigue, Gait Kinematics and Pelvis-Trunk Coordination

Abstract

Background: Carrying is one of the most frequently performed activities of daily living, particularly in industrial settings. However, as the carrying activity involves a direct exposure to several biomechanical mechanisms that can potentially affect the musculoskeletal function of the lower back, a prolonged use of the activity may lead to low back pain (LBP). Therefore, the aim of this doctoral study was to investigate the impact of anterior load carriage on muscle fatigue, spatiotemporal parameters and 3D kinematics of gait, and pelvis-trunk coordination. Methods: This cross-sectional study involved 37 healthy people; 20 sedentary individuals and 17 manual workers. All participants were instructed to perform an isometric back endurance test and two gait conditions: 1) standard gait and 2) carrying gait whilst carrying a safe-maximum load (max-kg gait). The spatiotemporal parameters and 3D kinematics of gait, as well as the pelvis-trunk coordination during the activity were measured using the Vicon Motion Analysis System. The muscle fatigue during the activity was measured based on the slope of median frequency (MFslope) of surface electromyography (EMG). The differences between the sedentary and the manual groups in all parameters were examined. Results: During the Ito test, there was no significant difference in the isometric back endurance and muscle fatigue between the groups. During the carrying activity, the manual group was able to carry 4 kg heavier maximum load compared to the sedentary group. For the gait parameters, there was a significant effect of load condition (standard gait to max-kg gait) on cadence (increased by 10 steps/minute), stride length (reduced by 4 cm) and stride time (reduced by 0.09 seconds). For the gait kinematics, there was a significant effect of load condition during stance phase on the range of motion (ROM) of ankle (flexion-extension), left hip (flexion-extension, with significant interaction effect), pelvic tilt, left pelvic axial rotation and all trunk movements. For the pelvis-trunk coordination, there was a significant increase in the percentage of in-phase coordination across the activity in flexion-extension (11% increase in the manual group only), lateral flexion (10% increase in the manual group, 5% increase in the sedentary group but on the right side only) and axial rotation (23% increase on the right side only). Conclusion: The results suggested that both manual and sedentary groups demonstrated a similar pattern of changes in spatiotemporal parameters regardless of their maximum carrying load. However, the differences in gait kinematics and pelvis-trunk coordination between the groups may indicate common body strategies to adapt with a safe-maximum load limit. Therefore, this study had established a biomechanical baseline of anterior load carriage among healthy population that can be used to guide further research investigation on specific group of people or patients as a part of functional capacity evaluation.

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Identifiers

ORCID for Joanna Adams: orcid.org/0000-0003-1765-7060

ORCID for Martin Warner: orcid.org/0000-0002-1483-0561

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