ALTERED NEUROMUSCULAR CONTROL PATTERNS IN THE PRESENCE OF LOW BACK PAIN

Abstract

Spinal stabilization through appropriate neuromuscular responses to external perturbations is important in the prevention and rehabilitation of low back pain (LBP). Muscle synergism, coordination and imbalances are terms used to describe the neuromuscular strategies considered important to actively maintain spinal stability. We recorded surface electromyographic (EMG) recordings from healthy controls (CON) and those with chronic, mechanical low back pain during performance of an exercise model that dynamically challenged lumbar-pelvic stability. Those with LBP showed greater variation in amplitude in response to the perturbations imposed by the exercise model, and demonstrated a lack of synergistic and antagonistic coactivation compared to the CON group.

The purpose of this study was to compare the neuromuscular control strategies used by those with LBP and those without to complete a standardized task aimed at dynamically challenging stability of the lumbar spine and pelvis.

Those with LBP activated their muscles in a more asynchronous manner than normal controls, illustrating an alteration in neuromuscular control that should be a focus of therapeutic intervention strategies aimed at prevention and rehabilitation of LBP.

These data illustrate a need for neuromuscular retraining, focusing on muscle coactivation in response to dynamic perturbations rather than a single perturbation.

Surface EMG recordings from two trunk extensor and five abdominal muscle sites were recorded from twenty-four men without LBP and fourteen men with chronic LBP while they performed a task that dynamically challenged lumbar spine and pelvis stability. The EMG amplitudes recorded from the upper and lower rectus abdominus sites were significantly (p< 0.05) lower for the LBP compared to the CON group. The temporal EMG profiles were compared using a statistical pattern recognition technique. This analysis showed that the LBP group used different patterns of synergistic muscle coactivity compared to the highly coordinated manner in which all seven muscles were recruited for the CON.

These results quantify the neuromuscular control differences between the two groups providing a foundation for developing an objective classifier of neuromuscular control impairments associated with LBP. In future this approach could assist in directing therapeutic interventions in particular those aimed at muscle reeducation.