Comparing the effects of static stretching and strengthening in lengthened position on EMG activity of hamstring muscle in patients with chronic non-specific LBP having shortened muscle: a randomised controlled clinical trial

Abstract

Introduction: Stretching and strengthening exercises are commonly used to improve muscle tightness. The objective of this trial was to compare the electromyography (EMG) activities of the shortened hamstring in chronic non-specific LBP patients after 12 sessions of static stretching or strengthening exercise.Methods: Forty-five patients were randomly allocated to either of three groups. All patients received the heat and transcutaneous electrical stimulation to the low back area. Also, specific interventions for (1) Static stretching group (n = 15), (2) Strengthening of hamstring muscle in its lengthened position group (n = 15) and no extra intervention for (3) Control group (n = 15) were applied. Blinded assessments of EMG of hamstring, disability and pain were undertaken at baseline and 12 sessions of interventions.Results: No significant difference in change in EMG records due to intervention was found between the three groups (p > .05). Comparing the post-intervention with the baseline results, change in hamstring EMG activity in the three groups was not different significantly (p > .05). Moreover, the result of comparison between groups did not show any significant differences in the mean of secondary outcome measures (pain and disability) either (p > .05).Conclusions: Neither static stretching nor strengthening exercise in the lengthened position for hamstring muscle tightness significantly affected EMG activity of this muscle.