The effect of a lower extremity kinematic constraint on lifting biomechanics

Abstract

Leaning against a stationary barrier during manual materials handling tasks is observed in many industrial environments, but the effects of this kinematic constraint on low back mechanics are unknown. Thirteen participants performed two-handed lifting tasks using both a leaning posture and no leaning posture while trunk kinematics, muscle activity and ground reaction force were monitored. Results revealed that lifting with the leaning posture required significantly less activity in erector spinae (26% vs. 36% MVC) and latissimus dorsi (8% vs. 14% MVC), and less passive tissue moment compared with the no leaning posture. Peak sagittal accelerations were lower when leaning, but the leaning posture also had significantly higher slip potential as measured by required coefficient of friction (0.05 vs. 0.36). The results suggested that the leaning lifting strategy provides reduced low back stress, but does so at the cost of increased slip potential.

Does the presence of a vertical barrier influence sagittal spinal curvature or range of motion in young females?

“…However these findings are in contrast with those of Jin and Mirka [21] who investigated the effect of a kinematic constraint on lifting biomechanics. These authors demonstrated that reaching over a barrier to lift resulted in greater lumbar curvature than the same lift completed whilst leaning on the barrier.…”