Two Methods for Improvement of Short Hamstrings in Healthy Individuals

Shortness of skeletal muscles may cause musculoskeletal disorders of body; improvement of these muscles may improve posture and body function. The aim of this study was to compare the effects of ultrasound (US) together with stretch and hold relax (HR) techniques in increasing the muscle length. It was a randomized trial with intention-to-treat analysis and assessor blinding. A total of 34 male students (18-24 years old) who had bilateral hamstring shortness (straight leg raise (SLR) < 65 degrees) were candidates for the study. Group one received US with stretching, group two received HR method and group three or control group did not receive any special treatment and had their normal daily living activities. Group one received stretching with 3 MHz continuous US (1.5 W/cm2) for four minutes. Group two (HR) received four cycles of HR training including 20 seconds of contraction and 10 seconds of relaxation. The hamstring muscle was passively taken to the end of the range. The assessment methods included passive SLR and passive knee extension (PKE), using goniometry. The results of the study (SLR and PKE) indicated that the mean of range of motion( ROM ) in the two treatment groups increased significantly during the treatment period, compared to the control group. Comparison of the two treatment methods, US with stretch and HR, revealed that there was no significant difference between the two methods in terms of ROM in SLR and passive extension. The two treatment methods had similar effects and there were no significant difference between them, while significant improvement was seen in the experimental groups compared with the control group.