Study on Spine and Joint Stability During Repetitive Lifting

Background on Chronic Low Back Pain

Chronic low back pain (CLBP) poses a significant health challenge, impacting both societal well-being and economic costs. Individuals suffering from CLBP often experience a marked decline in their quality of life, with daily activities becoming increasingly difficult and painful. This condition is especially problematic for individuals in occupations that require repetitive movements over extended periods. The relationship between CLBP, fatigue, and joint stability remains an important area of research.

Research Focus and Methodology

A recent study published in Human Movement Science aimed to explore the effects of lifting-induced fatigue on the stability of the spine, hips, knees, and ankles in both healthy individuals and those suffering from chronic low back pain. The study involved fourteen healthy males, averaging 23 years old, and fourteen males with nonspecific CLBP, averaging 25 years old. Participants engaged in a lifting routine using two dumbbells, with a combined weight of 15% of their body weight, lifting from the floor to waist height and back down until they experienced fatigue.

The researchers employed a Vicon motion capture system to collect three-dimensional kinematic data of the joints during the lifting tasks. To assess the data, they utilized the nonlinear Lyapunov exponent (LyE) to evaluate the local stability of each joint across three anatomical planes: sagittal, transverse, and frontal.

Key Findings

The study’s findings indicated that lifting-induced fatigue significantly impacted spine stability in the sagittal plane, while hip stability was affected across all anatomical planes. Conversely, the stability of the knees and ankles did not show significant changes as fatigue progressed. These results suggest that unstable lifting-lowering conditions are associated with late fatigue. Notably, no significant interaction was found between chronic low back pain and fatigue on joint stability.

Although hip stability appeared slightly compromised in individuals with CLBP on the frontal and transverse planes, it remained stable in the sagittal plane. Additionally, knee and ankle stability showed no significant differences between healthy participants and those with CLBP during both early and late fatigue conditions.

Conclusion and Future Directions

The study concluded that both healthy individuals and those with chronic low back pain experienced decreased stability in the spine and hips as fatigue progressed. Researchers attributed this decline to muscle fatigue, although this was not directly measured. In contrast, knee and ankle stability remained unaffected, possibly due to participants modifying their joint control strategies as a means to reduce pain.

Moving forward, the authors suggest further investigation into how different lifting techniques may influence joint stability. This enhanced understanding of the mechanisms underlying fatigue, chronic low back pain, and motor impairment could aid physiotherapists in devising more effective treatment strategies and programs.

Reference

Asgari N, Sanjari MA, Esteki A. Local dynamic stability of the spine and its coordinated lower joints during repetitive lifting: Effects of fatigue and chronic low back pain. Hum Mov Sci. 2017;54:339-346. doi:10.1016/j.humov.2017.06.007