Characterizing Local Dynamic Stability of Lumbar Spine Sub-regions During Repetitive Trunk Flexion-Extension Movements.

Dennis J Larson,Derek P Zwambag,Stephen H M Brown,Yunxi Wang

doi:10.3389/fspor.2019.00048

Dennis J Larson, Derek P Zwambag + Show 2 more

Open Access

https://doi.org/10.3389/fspor.2019.00048

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Abstract

Using a technique of tracking intersegmental spine kinematics via skin surface markers, this study aimed to estimate local dynamic spine stability across smaller sub-regions (or segments) of the lumbar spine while also considering the impact of an external pelvic constraint during repetitive movements. Sixteen participants (10 males) performed two trials [Free Motion (FM), Pelvis Constrained (PC)] each consisting of 65 repetitive trunk flexion-extension movements to assess dynamic spine stability using maximum Lyapunov exponents (LyE). First, results indicated that LyE obtained from analysis of 30 repetitive flexion-extension movements did not differ from those obtained from analysis of greater numbers of repetitive movements, which aligns with results from a previous study for the whole lumbar spine. Next, for both males and females, and FM and PC trials, the most caudal region of the lumbar spine behaved the most dynamically stable, while upper lumbar regions behaved the most dynamically unstable. Finally, females demonstrated greater lumbar and intersegmental stability (lower LyE) during PC trials compared to FM, while males demonstrated slightly decreased lumbar and intersegmental stability (higher LyE) during PC trials compared to FM; this resulted in PC trials, but not FM trials, being different between sexes. Altogether, these data show that dynamic stability of lumbar spine sub-regions may be related to the proximity of the motion segment to rigid skeletal structures, and that consideration is needed when deciding whether to constrain the pelvis during analyses of dynamic spine stability.

Highlights

Information regarding neuromuscular control of human movement can be obtained through the application of non-linear dynamics analyses of repetitive motion patterns
The results demonstrated that 30 repetitive flexion-extension cycles produced both whole lumbar and intersegmental dynamic stability values that were not different from those obtained using higher numbers of cycles (Figure 4), which aligns with previous research (Dupeyron et al, 2013)
It was hypothesized that lower lumbar vertebral segments (e.g., L4/L5) would demonstrate the lowest dynamic stability, due to lower back pain and injury often being linked to abnormal intervertebral spine motion/stability (Cholewicki and McGill, 1996; McGill and Cholewicki, 2001) and greater instability and degeneration being observed at lower vertebral levels (Friberg and Hirsch, 1949)

Summary

Introduction

Information regarding neuromuscular control of human movement can be obtained through the application of non-linear dynamics analyses of repetitive motion patterns. Studies investigating spine motion have most commonly affixed rigid bodies or sensors to the skin over the participant’s pelvis and thorax to obtain 3-dimensional (3D) angular kinematics of the whole lumbar spine (e.g., Howarth, 2014). This has enabled the study of lumbar spine dynamic stability under a variety of task conditions; only inferences could be made regarding intervertebral or intersegmental spine motion. With recent developments in the resolution with which spine skin-surface motion is tracked (Zwambag et al, 2018), we can estimate dynamic stability across smaller spine regions or segments and the whole lumbar spine concurrently

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