Exploring hamstrings flexion-relaxation phenomenon in experimental low back pain
Citation:Deshmukh, G. (2014). Exploring hamstrings flexion-relaxation phenomenon in experimental low back pain. An unpublished research thesis sbumitted in partial fulfilment of the requirements of the degree of Master of Osteopathy, Unitec Institute of Technology.
Permanent link to Research Bank record:http://hdl.handle.net/10652/2528
BACKGROUND: Flexion-relaxation phenomenon in lumbar erector spinae muscles is a normal phenomenon which is notably altered in cases of low back pain; however the characteristics of this phenomenon in the hamstring muscles is not well understood. OBJECTIVE: To investigate if the hamstrings extension-relaxation ratio was affected by experimental low back pain. Participants: Nineteen healthy, pain-free volunteers with mean age (SD) = 28.7 (6.7) years participated in the study. METHODS: Surface electromyography was used to measure activity in the bilateral hamstring and lumbar erector spinae muscles before and after hypertonic-saline-induced experimental pain of the lumber erector spinae muscles during trunk flexion-extension tasks. Average muscle activity during each phase and extension-relaxation ratio values were analysed for each muscle group (lumbar erector spinae, biceps femoris, and medial hamstrings) using repeated measure ANOVAs. RESULTS: Although pain conditions affected biceps femoris activity in full trunk flexion (P < 0.001), and medial hamstrings activity in extension (P = 0.025), the hamstring extension-relaxation ratio was not affected significantly by the experimental pain. CONCLUSION: Low back pain does not seem to directly affect hamstrings extension-relaxation ratio in an experimental setting