Long latency reflex response of superficial trunk musculature in athletes with chronic low back pain.

BACKGROUND AND OBJECTIVES: Incidence of Low Back Pain (LBP) in athletes is as high as 30%. Patients with LBP show altered postural and neuromuscular responses to various functional tasks. The objective of the study was to compare long latency reflex response (occurring between 40 to &nvsim; 100 ms duration) in athletes with chronic LBP with asymptomatic athletes. METHODS: Surface electromyography (EMG) of superficial trunk muscles - Rectus Abdominis (RA) and Erector Spinae (ES) were studied in athletes with chronic LBP (n=24) and asymptomatic athletes (n=25). Perturbations were introduced in standing both expectedly and unexpectedly. The latency of onset and the Root Mean Square (RMS) amplitudes within the reaction duration were compared between the two groups. RESULTS: The latency of onset was delayed in Unexpected perturbations but no change was observed in Expected tasks. The mean RMS amplitudes were significantly lower in both tasks for RA and in the Expected task for ES (p< 0.05). CONCLUSION: Chronic LBP athletes exhibit a delay in onset latency to Unexpected perturbations and reduced long latency response amplitudes to perturbation tasks compared to asymptomatic athletes. These changes could predispose athletes to recurrent low back pain and further injury. [ABSTRACT FROM AUTHOR]