Background and Aim: Only a few studies have been conducted to investigate the effect of ultrasound and duration of stretching on the enhancement of hamstring muscle flexibility. The purpose of this study was to determine the knee joint passive extension in male students with hamstring shortness and the effect of duration of stretching and ultrasound on the treatment of this deficit.
Materials and Methods: This clinical trial was performed in Zabol in 2005. Fifty students from a boys' intermediate school aged 12-14 years participated in the study through simple non-probability sampling. The subjects were randomly assigned to five treatment groups including ultrasound therapy, ultrasound therapy and fifteen seconds stretch, ultrasound therapy and thirty seconds stretch, only fifteen seconds stretch, and finally thirty seconds stretch. The range of knee joint passive extension (degree) as an indicator of hamstring muscle flexibility was measured before and after ten treatment sessions. The obtained data were analyzed at the significant level of PL0.05 using ANOVA and Student t-paired tests.
Results: Passive extension of the knee joint increased from 160.2±7.9 degrees to 163.3±7.5 degrees in the first group (P=0.001). In the second group it increased from 161.1±6.9 degrees to 166.5±5.9 degrees (P<0.0001); in the third group from 163.5±6.7 degrees to 171.2±5.9 degrees (P<0.0001), in the fourth group from 161±11.8 degrees to 164.4±11.3 degrees (P=0.005), and in the fifth group from 166.1±5.6 degrees to 171.1±4.8 degrees (P=0.001). There was not a significant difference between the five groups before (P=0.48) and after treatment (P=0.059).
Conclusion: It was found that hamstring muscle group flexibility increased in all the five remedial procedures. Although none of the procedures were significantly preferable to the rest in terms of increase in hamstring muscle group flexibility