The influence of hip extensor and lumbar spine extensor strength on lumbar spine loading during a squat lift

The Influence of Relative Hamstring Flexibility and Lumbar Extensor Strength on Lumbar and Pelvic Kinematics During a Stoop Lift

The objective of this study was to examine the influence of relative hamstring flexibility and lumbar extensor strength on lumbar flexion during a stoop lift. Lumbar flexion during stoop lifting has been associated with increased bending stress and load on the lumbar spine. The potential impairments that contribute to a flexed lumbar lifting posture during stoop lifting are unclear. Forty-nine healthy individuals (27 females and 22 males) between the ages of 18 and 40 participated. Strength of the lumbar extensors was measured with a motor-driven dynamometer, and relative hamstring flexibility was estimated with the passive knee extension test. Peak lumbar flexion and pelvis anterior rotation were quantified with 3D motion capture during a stoop lift. There was a positive correlation between relative hamstring flexibility and peak pelvis anterior rotation angle during the stoop lift (r = .544, P < .001). Meanwhile, there was a negative correlation between middle lumbar spine peak flexion and relative hamstring flexibility (r = -.538, P < .001) and a negative correlation between lumbar extensor strength and lower lumbar peak flexion (r = -.288, P = .045). Individuals with decreased strength and limited relative hamstring flexibility tended to exhibit increased lumbar flexion during stoop lifting.

Estimation of Lumbar Spine Loading of Low Back Pain Participant During Lifting Using an Open Source Musculoskeletal Model

Biomechanical modeling of spinal load during lifting in OpenSim has the potential for rehabilitation and clinical assessment. In the literature, several spinal models have been developed and validated with movement data from healthy individuals. Although these models are valid for predicting spinal load in healthy individuals, it is unknown whether these models are applicable for people with chronic low back pain (CLBP). This study aims to compare the application of the lifting full body (LFB) model between a healthy participant and a participant with CLBP. The participants performed the lifting activity, and the motion capture data was used to analyze how an open-source model predicts the loading of the lumbar spine. Peak spinal loading at L5/S1 joint was estimated as 3.9 kN for the healthy participant and 3.1 kN for the CLBP participant. The results suggest that a longer duration of lift and lower lumbar range of motion reduces lumbar spinal loading.