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Muscle Inhibition During Cycling in a Patient with Chronic Low Back Pain: Effect of Brief Electrical Stimulation

Abstract

Roy Bechtel, Scott Benjamin and Liu Wei

Background and purpose: This case study reports patterns of muscle inhibition and techniques for therapeutic intervention in a well-trained cyclist with chronic low back pain (CLBP) following a discectomy at L5-S1. It has been shown that repeated or prolonged flexion can lead to inhibition of the spine stabilizing muscles. Competitive cyclists exert high effort in a flexed posture for prolonged periods. Segmental muscle inhibition could lead to LBP and segmental instability in this population. The purpose of our case study was 1) to determine if a competitive cyclist with CLBP would demonstrate muscle inhibition at the symptomatic level and 2) to determine if a therapeutic intervention (electrical muscle stimulation) applied to the symptomatic level for a short period, could affect function.

Methods: One subject, a 42-year-old male, rode a stationary bike trainer at various speeds and gear configurations for specified time periods. Surface EMG was recorded at L3-L4, L4-L5 and the L5-S1 segmental levels for 10 seconds during 7 trials. Electrical stimulation was applied in prone for a period of 15 minutes, using square waves with 120 ms pulse width at 35 Hz. Two cycling trials were conducted before therapeutic intervention and five were recorded after intervention.

Analysis/results: Analysis was performed using normalized RMS surface EMG. Therapeutic intervention, consisting of 15 minutes of electrical muscle stimulation, improved muscle recruitment at the symptomatic level to values better than adjacent segments. Further, this stimulation effect persisted up to 15 minutes while cycling continued. Discussion: Even though competitive cyclists are subjected to a flexed spine position for long periods of time, electrical stimulation may lead to improvement in lumbar muscle recruitment, and presumably to improved spinal stability and motor control. Further studies are needed to determine the optimal timing of stimulation and how long the effect can last under competitive conditions.

Conclusion: Cyclists with CLBP are at risk for inhibition of the lumbar stabilizing muscles. With electrical stimulation and proper rehabilitation, this inhibition may be reduced. Clinical Implications; This study exposes one of the neuromusculoskeletal risks competitive cyclists with CLBP can face, and proposes a relatively novel intervention. Further research is required to validate these results.