STRETCHING EXERCISES - EFFECT ON PASSIVE EXTENSIBILITY AND STIFFNESS IN SHORT HAMSTRINGS OF HEALTHY-SUBJECTS

Passive muscle stretch tests are common practice in physical therapy a nd rehabilitation medicine. However, the effects of stretching exercis es are not well known. With an instrumental straight-leg-raising set-u p the extensibility, stiffness, and electromyographic activity of the hamstring muscles have been experimentally determined and the effects of stretching exercises have been evaluated. Fourteen volunteers, aged 20 to 38 years (mean 27.3) were selected from a young healthy populat ion with the toe-touch test (finger-ground distance greater than Oem), and a straight-leg-raising angle about 80 degrees. According to usual standards the diagnosis was short hamstrings. One group of seven subj ects was treated during 4 weeks with a daily home exercise program aim ed at stretching the hamstrings, whereas the untreated group was used as a control. Instrumental straight-leg-raising was performed in the s ubjects of both groups. The significance of the differences between th e mean values was determined with the Student's t-test. Comparison of the data obtained before and after the muscle stretching program showe d a slight but significant increase in the extensibility of the hamstr ings accompanied with a significant increase of the stretching moment tolerated by the passive hamstring muscles. However, the elasticity re mained the same. It is concluded that stretching exercises do not make short hamstrings any longer or less stiff, but only influence the str etch tolerance. (C) 1994 by the American Congress of Rehabilitation Me dicine and the American Academy of Physical Medicine and Rehabilitatio n