Objective: The purpose of this research was to compare the erector spine flexion relaxation phenomenon between subjects with and without history of Low back pain.
Materials & Methods: In this Quasi-experimental study, 15 persons with history of low back pain were selected simply from convenient samples and 15 healthy persons were selected by matching method. Surface Electromyography and Electrogoniometery were used. Subjects performed lifting and lowering tasks with load and without load as randomly, then Prolonged Static lumbar flexion were maintained for 7 minutes, then lifting and lowering tasks repeated. Erector spine Flexion relaxation phenomenon before and after prolonged static lumbar flexion (position), with and without load, in two groups were compared by 3 ways mixed ANOVA.
Results: The interactions between Load * position (P=0.120) and group* load (P=0.365) were insignificant, but interaction between group * position were significant (P<0.001). After prolonged lumbar flexion position, erector spine flexion relaxation phenomenon started later in subjects with history of low back pain (P<0.001), but there is no different significant in subjects without history of low back pain (P=0.468).
Conclusion: After prolonged lumbar flexion position, erector spine flexion relaxation phenomenon started later in subjects with history of low back pain, but there is no different significant in subjects without history of low back pain.