Behm et al. set out to answer this. The researchers conducted a systematic review (a study of studies) with the objective of comparing the effects of static stretching (SS), dynamic stretching (DS), and proprioceptive neuromuscular facilitation (PNF) on performance, range of motion (ROM) and injury risk. This study includes 125 studies incorporating 270 maximal performance measures examining the acute effects of SS on performance. These performance measures were: vertical jump height, sprint running time, chest and bench press 1-repetition maximum and maximal voluntary contractions (MVC).
The weighted estimates of these measures showed a moderate 3.7% mean performance reduction from SS minutes before performance. There is a dose-response relationship of SS and performance. Greater than or equal to 60s or more of SS before performance is more likely to result in a significant performance impairment. Shorter durations of SS have little effect. 98 studies looked at in this review gave participants longer stretch durations at or above 60s and incorporated 210 maximal performance measures and found 109 significant reductions. There were greater impairments from SS with 60s or more of stretching (-4.6%) vs <60 s (-1.1%).
A dose-response relationship could not be established for PNF or DS. For DS, it appears that greater than 2 minutes and faster frequencies provide a greater performance increase. The author suggests that it is perhaps wise to perform SS and PNF 10 or more minutes before the performance event with DS being preferred to be conducted closer to performance.
This studied found that static stretching and PNF had no clear effect on all-cause or overuse injuries. Further, static stretching was not found to improve athletic performance when done before hand; if anything there is a growing body of research that suggests SS invokes negative effects on maximal muscular performance.
However, dynamic stretching has been indicated to significantly improve athletic performance, there does not seem to be sufficient evidence to conclude if DS improves injury risk.
The Take-home message
Both SS and PNF decreased performance (-3.7%) and (-4.4%) and DS increased performance (+1.3%). These changes are small to moderate when testing was performed 3-5 minutes after stretching. The authors mention that most stretch to performance times are usually of 10 minutes or greater duration. Those studies that conducted tests after 10 minutes found statistically trivial performance changes, unless the stretch protocols were extreme enough.
SS had a greater performance reduction effect to strength (-4.8%) vs. power-speed (-1.3%) tests. All forms of muscle stretching have been shown to provide a significant acute ROM benefit.
Does stretching effect injury risk?
Out of the 8 studies they analyzed that studied injuries only 2 reported a benefit of stretching. 4 randomized controlled trials showed no benefits of stretching on the rates of ankle sprains.
The Authors of this study conclude that SS and PNF stretching show no overall effect on all-cause injury (being injured for any cause) or overuse injuries. However, there may be a benefit in reducing acute muscle injuries with running, sprinting, or other repetitive contractions. six studies researched the effects of stretching on the prevalence of acute muscle injuries. Taken together, these studies indicate a 54% risk reduction in acute muscle injuries associated with stretching. Of note, most research has demonstrated that stretching before exercise is ineffective in reducing soreness or other symptoms of muscle damage.
- Behm, David G. et al. “Acute effects of muscle stretching on physical performance, range of motion, and injury incidence in healthy active individuals: a systematic review.” Applied physiology, nutrition, and metabolism = Physiologie appliquee, nutrition et metabolisme 41 1 (2016): 1-11 .