Background
Although stretching can acutely increase joint range of motion (ROM), there are a variety of factors which could influence the extent of stretch-induced flexibility such as participant characteristics, stretching intensities, durations, type (technique), and muscle or joint tested.
Objective
The objective of this systematic review and meta-analysis was to investigate the acute effects of stretching on ROM including moderating variables such as muscles tested, stretch techniques, intensity, sex, and trained state.
Methods
A random-effect meta-analysis was performed from 47 eligible studies (110 effect sizes). A mixed-effect meta-analysis subgroup analysis was also performed on the moderating variables. A meta-regression was also performed between age and stretch duration. GRADE analysis was used to assess the quality of evidence obtained from this meta-analysis.
Results
The meta-analysis revealed a small ROM standard mean difference in favor of an acute bout of stretching compared to non-active control condition (ES = −0.555; Z = −8.939; CI (95%) −0.677 to −0.434; p < 0.001; I2 = 33.32). While there were ROM increases with sit and reach (P = 0.038), hamstrings (P < 0.001), and triceps surae (P = 0.002) tests, there was no change with the hip adductor test (P = 0.403). Further subgroup analyses revealed no significant difference in stretch intensity (P = 0.76), trained state (P = 0.99), stretching techniques (P = 0.72), and sex (P = 0.89). Finally, meta-regression showed no relationship between the ROM standard mean differences to age (R2 = −0.03; P = 0.56) and stretch duration (R2 = 0.00; P = 0.39), respectively. GRADE analysis indicated that we can be moderately confident in the effect estimates.
Conclusion
A single bout of stretching can be considered effective for providing acute small magnitude ROM improvements for most ROM tests, which are not significantly affected by stretch intensity, participants’ trained state, stretching techniques, and sex.
Key Points
1 The meta-analysis on joint range of motion (ROM) increases revealed a small effect size in favor of an acute bout of stretching compared to the control condition.
2 Subgroup analysis revealed a significant increase in ROM with sit and reach, hamstrings, and triceps surae tests, but no improvement with the hip adductor tests. Whereas all moderating variables presented significant increases in ROM, further subgroup analyses revealed no significant difference in ROM gains with the stretch intensity, trained state of the participants, stretching techniques, and sex.
3 A meta-regression showed no relationship between the effect sizes to age and stretch duration, respectively.
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