A randomized clinical trial comparing the effects of two different durations of muscle energy technique on neck pain, trigger points, range of motion and neck disability index
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BACKGROUND Mechanical neck pain (MNP) has been described as any condition which changes joint mechanics and muscle structure / function. A review of the current literature shows that Muscle Energy Technique (MET) is an effective manual therapy for patients with acute or chronic MNP. The most useful contraction of MET however remains unknown. Some authors advocate the use of a two to seven second MET (Brous, 2005; Greenman, 2003 Mitchell, Moran, and Pruzzo, 1979) whilst other authors have recommended contraction durations of 30 to 60 seconds (Chaitow, 2006; Feland et al., 2001; Bandy and Irion, 1994). This study aimed to establish the most suitable contraction duration of MET in the treatment of chronic MNP by comparing a short duration MET to a long duration MET. OBJECTIVES Objectives included the comparison of a five-second (short duration) MET and a 45-second (long duration) MET in terms of subjective and objective findings in the treatment of chronic MNP. METHOD This randomized clinical trial, with 53 participants utilised a randomization table for group allocation. For the purpose of this study an average of the short contraction durations reported in the literature i.e. five seconds, was used for the short duration MET treatment and an average of the long contraction durations reported in the literature i.e. 45 seconds, was used for the long duration MET. Group A (n=26) received the five-second MET contraction and Group B (n=27) received the 45-second MET contraction treatment. Objective measures included the cervical range of motion (CROM Goniometer) and tenderness levels (algometer). The subjective measures were pain (Numerical Rating Scale-101) and MNP related disability (CMCC Neck Disability Index). Each participant received four treatments over a two week period, with all data collected prior to the first and third consultations and at the final follow up. Data were analysed using the SPSS version 20 (IBM), with a statistically significant p value set at <0.05. Repeated measures ANOVA testing determined the intergroup effects. To assess intergroup effects and effects of the intervention a time x treatment group interaction analysis was conducted. Profile plots assessed direction and trend of the effect of the treatment. RESULTS Intra-group analysis of both groups showed significant improvement in all of the range of motion measures (over time) except for Flexion, Right Lateral Flexion and Left Rotation in Group A and Flexion, Extension, Right Lateral Flexion and Left Lateral Flexion in Group B. The intra-group analysis also showed a significant improvement in the neck disability index scores and the tenderness measurements in both groups. The results of the inter-group analysis revealed that only Left Lateral Flexion showed a significant treatment effect (p=0.011) where increased scores were shown in Group A and not in Group B. There was no treatment effect for the neck disability index scores or the tenderness measurements. CONCLUSION It may be concluded that both treatment protocols were equally effective for all outcomes except for Left Lateral Flexion where the five-second MET seemed to show greater degree of improvement than the 45-second MET. The neck disability index scores and the pain levels of participants in both groups showed an improvement. No treatment was better than the other in terms of these two variables. This therefore seems to support the use of the shorter duration MET in clinical practice.