The influence of spine position on measures of lower extremity neural sensitivity

BackgroundThe Slump Test evaluates neural tissue mechanosensitivity in individuals with lower extremity symptoms. However, there has been little research assessing the role of altering lumbar spine positioning on sensory response. Therefore, this study compared differences in subjective and objective findings observed in different lumbar spine positions during neurodynamic testing.MethodsHealthy participants were assessed using the 90/90 knee extension (KEA) to determine available ROM, followed by lumbar spine flexed slump (FS), and lumbar spine extended slump (ES). Outcomes included knee extension angle, hamstring EMG activity (%MVIC), distal extent of sensory response, and qualitative mechanosensory response.ResultsForty participants (23.95 ± 2.64 years; 14 male/26 female) completed the study. Significantly less knee extension ROM was found for ES vs. FS (p < .001) and ES vs. KEA (p = .037). A greater proportion of distal symptoms were observed during ES vs. FS (p < .05). FS and ES showed higher EMG values than KEA (p < .001), with no difference between the two slump conditions.ConclusionIn this healthy population, ES produced the greatest distal sensory responses, highest EMG activity, and lowest knee extension ROM. Incorporating lumbar extension during slump testing may be useful to determine mechanosensitive behavior, but further research is needed in clinical populations.The trial was prospectively registered at clinical trials.gov. NCT05313217.