{'fraction_non_alphanumeric': 0.029043280182232345, 'fraction_numerical': 0.013097949886104784, 'mean_word_length': 5.5559701492537314, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
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 1 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.