Assessment of erector spinal muscles activation in pre and post training with surface electromyography in an equestrian athlete with recurring non-specific low back pain: a case report.

Objective Overview

• This case report investigates whether surface electromyography (sEMG) can detect changes in spinal erector muscle activation before and after training in an equestrian athlete who suffers from recurring non-specific low back pain (LBP).
• The study examines the flexion relaxation phenomenon (FRP) and flexion relaxation ratio (FRR) to assess muscle activation in relation to pain levels measured by the Numeric Pain Rating Scale (NPRS).

Introduction and Background

• Low back pain (LBP) is commonly reported among horse riders, but the specific causes related to equestrian activities have not been well studied.
• Existing research tends to focus on the horse’s health, with little attention to the rider’s musculoskeletal issues.
• This study targets this gap by evaluating muscle activation patterns in a rider with recurring non-specific LBP to understand potential mechanisms behind the pain.

Methodology

• Subject: One equestrian athlete experiencing lower back pain post-training.
• Measurement Tool: Surface electromyography (sEMG) using BTS FREEEMGM 1000 wireless probes was applied to the spinal erector muscles.
• Procedure: sEMG recordings were taken before and after training over two days to observe changes in muscle activation.
• Parameters Measured:
  • Flexion Relaxation Phenomenon (FRP): A normal muscular relaxation pattern during forward flexion of the spine.
  • Flexion Relaxation Ratio (FRR): A quantitative measure comparing muscle relaxation during flexion with activation during standing phases.
  • Numeric Pain Rating Scale (NPRS): Used to quantify the athlete’s subjective pain level.

Findings

• Both FRP and FRR occurred correctly before and after training, on both measurement days, indicating that muscle relaxation during spinal flexion was functioning normally.
• Post-training FRP values were closer to the RMS (root mean square) values measured during the standing phase, which suggests an increase in muscle activation or reduced ability of spinal erectors to fully relax after training.
• The closer FRP to standing RMS post-training correlated with higher NPRS pain scores, indicating that increased muscle activation or incomplete relaxation might be related to exacerbated low back pain post-exercise.
• These findings support the ability of sEMG to detect subtle neuromuscular changes linked with LBP in this athlete.

Interpretation and Implications

• The study suggests that surface electromyography can be a useful tool to monitor spinal erector muscle behavior in equestrian athletes with LBP.
• The closer similarity between post-training FRP values and standing RMS may reflect muscle fatigue, protective muscle guarding, or altered motor control associated with pain.
• This neuromuscular information can assist clinicians and trainers in tailoring rehabilitation or training programs to improve muscle function and potentially reduce pain.

Limitations and Recommendations

• The study is limited as a single-patient case report, so generalizability is low.
• Larger sample sizes are needed to confirm these findings and establish normative data on spinal erector activation patterns in equestrian athletes.
• Additional measurements over time could clarify the relationship between training load, muscle activation changes, and pain levels.
• Future research should also investigate other factors contributing to LBP in this population, including biomechanics, posture, and horse-riding techniques.

Conclusion

• This case report demonstrates that surface electromyography can detect changes in spinal erector muscle activation associated with recurring LBP in an equestrian athlete.
• The occurrence of FRP and FRR pre- and post-training, alongside pain ratings, highlights the potential utility of sEMG in monitoring rehabilitation and training effects.
• The results call for more comprehensive studies to better understand and manage LBP in riders, potentially improving athlete health and performance.