A comparison of two muscle energy techniques for increasing flexibility of the hamstring muscle group

Variations in the application of muscle energy technique (MET) for increasing the extensibility of muscles have been advocated, but little evidence exists to support the relative merit of a particular approach. This study investigated two types of muscle energy techniques that have been advocated in the osteopathic literature that differ primarily in the duration of the post-contraction stretch phase. Forty asymptomatic participants (mean age=22.1+/-3.5, male female=1:4) were randomly allocated to one of two groups (Group 1: MET with 30-s post-isometric stretch phase; Group 2: MET with 3-s post-isometric stretch phase). Hamstring length was measured using active knee extension (AKE). Participants received an initial application of the allocated intervention, and then a second application 1 week later. Analysis with a split-plot ANOVA revealed a significant effect of time (F(3,36)=42.30;p<0.01), but no significant time*group interaction (F(3,36)=0.12; p=0.95). Post-hoc analysis revealed that the significant differences over time occurred between pre- and post-measurements at both weeks, and between post-Week 1 and pre-Week 2 measurements. Both techniques appeared to be equally effective in increasing hamstring extensibility, and there appeared to be sustained improvement 1 week following the initial treatment. The findings suggest that altering the duration of the passive stretch component does not have a significant impact on the efficacy of MET for short-term increases in muscle extensibility.