The influence of kinesiophobia on trunk muscle voluntary responses with pre-programmed reactions during perturbation in patients with chronic low back pain.

The purpose of this study was to examine the relation between fear of movement and perturbation induced electromyographic global trunk muscle voluntary responses with pre-programmed reactions among persons with chronic low back pain (CLBP). CLBP subjects (n = 25) were challenged to unexpected and expected perturbations on stable and unstable surfaces. 'Tampa scale for kinesiophobia - Adjusted version-13' was used to measure kinesiophobia. Regression analysis revealed significant negative correlation between kinesiophobia scores and voluntary responses of rectus abdominis (RA) for unexpected perturbations on stable (r = -0.69, 95% of CI: -0.85 to -0.40, p < 0.000, r(2) = 0.41) and unstable surfaces (r = -0.47, 95% of CI: -0.72 to -0.09, p < 0.018, r(2) = 0.29). The activity of erector spinae was not influenced by most of testing conditions in the study except task on unstable surface for expected perturbation (r = -0.593, 95% of CI: -0.8 to -0.25, p = 0.002, r(2) = 0.15). RA activity and kinesiophobia score of the CLBP population was significantly inversely associated during anteriorly directed unexpected perturbations. In our study, the significant association between fear of movement and the trunk muscle responses was differentially influenced by expected and unexpected postural demands.

The magnitude of pre-programmed reaction dysfunction in back pain patients: experimental pilot electromyography study.

BACKGROUND: Preprogrammed reactions (PPR) appear at a latency of higher than 40 ms, but before the voluntary muscle responds (approximately 120 ms) to postural perturbations. OBJECTIVE: To examine the difference in magnitude of preprogrammed reactions in patients with chronic low back pain (CLBP) and without low back pain. METHODS: we analyzed electromyographic Root Mean Square (RMS) amplitudes of asymptomatic (n=25) and CLBP patients (n=25) on stable and unstable surfaces during expected and unexpected perturbations for rectus abdominus and erector spinae muscles. The mean PPR and PPR-combined voluntary response RMS amplitudes (VRPPR) were compared between the two groups. To find the presence of PPR in LBP patients, a criteria was set that the obtained PPR RMS amplitude value should exceed 60% mean reflex RMS amplitude that occur within 50 ms after perturbation. RESULTS: Fleiss' kappa revealed a good agreement (kappa = 0.7 to 0.9) among raters for absence of PPR in patients with CLBP and presence of PPR in asymptomatic population. The two way ANOVA revealed significantly different mean PPR and VRPPR RMS amplitudes between asymptomatic and LBP population for rectus abdominus and erector spinae muscles (p<0.05). CONCLUSION: PPR responses were found absent (<60% of Mean Reflex RMS) in patients with CLBP. Further, patients with CLBP demonstrated lower PPR amplitudes with higher peak voluntary responses compared to asymptomatic population, indicating difficulties in presetting of voluntary responses for regaining postural stability after perturbation.