The effects of hamstring stretching on range of motion: A systematic literature review

Study Design: Systematic literature review. Objective: Investigate the literature regarding the most effective positions, techniques, and durations of stretching to improve hamstring muscle flexibility. Background: Hamstring stretching is popular among physical therapists, athletic trainers, and fitness/coaching professionals; however, numerous stretching methodologies have been proposed in the literature. This fact establishes a need to systematically summarize available evidence in an attempt to determine the most effective stretching approach. Methods: A list of 28 pertinent manuscripts that included randomized and clinical trials was created according to specific inclusion/exclusion criteria. These manuscripts were critically reviewed for quality according to the Physiotherapy Evidence Database (PEDro) (10-point) scale and descriptive information about the stretching parameters employed in the research. Results: Cumulatively, 1338 healthy subjects were included in the reviewed studies. Methodological quality scores ranged from 2 to 8 (mean +/- SD, 4.3 +/- 1.6). Several methodological flaws were frequently recognized, including failure to conceal group allocation or perform blinded assessment. All studies reported improvements in range of motion after stretching. Conclusions: Overall, methodological quality was poor, with only 21.4 % (6/28) of studies achieving a score between 6 and 8. Thus it was difficult to confidently identify I most effective hamstring stretching method. Instead, the evidence appears to indicate that hamstring stretching increases range of motion with a variety of stretching techniques, positions, and durations.