Dear Back Pain, why are you Here?

Author: Hannah McMaster

Hannah McMaster’s current research project alongside Aurora Battis concerns the phenomenon of why some individuals develop low back pain (LBP) when standing for extended periods of time, and why some individuals do not. Throughout the day the body is undergoing changes caused by natural shifts in mechanical demands over a day-night cycle (i.e., diurnal variation). A possible mechanism behind the development of standing LBP is the constant gravitational compressive load that acts on the spinal column which can lead to reduced intervertebral disc height over the course of the day. Diurnal variation and the mechanics of the spinal column are being explored to understand the role of these phenomena on the development of standing LBP.

This project aims to understand the impact of diurnal variation on perceptions of standing LBP and is also determining if changes in posture and standing balance produce the variation(s) in standing LBP. To evaluate this, the following technologies are being used; electromyography (to measure muscle activation), 3D motion capture (to measure spine posture), and 3D force platforms (to measure standing balance). The findings of this study will provide further information regarding how within-day changes in spine mechanics impact the perception(s) of standing LBP, and the control of standing balance.

Figure 1. Subject with rigid body and free body markers attached. Marker placement is done according to pre-determined locations (i.e. tibialis anterior). 3D locations of markers in space can be detected by the 3D motion capture Vicon Nexus application.

Currently, Aurora and Hannah are focused on developing their workflows using Vicon Nexus software. This application is a 3D motion capture system that records the movement of rigid body and free body markers in space shown in Figure 1. Full body motion capture data are acquired (Figure 1), and the software automatically labels and scales each individual’s body parameters (i.e., segment lengths, location of joint centers). Once the marker data are labelled, these data will be exported as .c3d files for further post-processing in MATLAB to evaluate lumbar spine posture during quiet standing trials in future data acquisition sessions!

Figure 2. Labelled Vicon Skeleton (VSK) from a Custom Vicon Template (VST). A trial of a subject that has been recorded in the Vicon Nexus system and the coloured spheres are markers that have been automatically labeled using a custom VST developed by Aurora and Hannah.

The next step in this study is to begin collecting data. If you are interested in participating in this fascinating study, please contact our lab at +1 (905) 688-5550 x5623 or contact Aurora at to see if you meet the eligibility criteria!

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