Over the past several years, it has been widely reported that static stretching prior to exercise can decrease speed, power and strength, indicating that if you are completing an event where speed or power is necessary, you should skip the static stretching and stick with either dynamic stretching or a cardiovascular warm-up. A recent review of literature published in Medicine & Science in Sports & Exercise is calling these findings into question however. They completed a systematic literature review and found that a static stretch maintained for no longer than 30 seconds per stretch had no effect on maximal muscle performance. Stretches lasting 30-45 seconds showed mixed results, with 50% demonstrating a decrease in strength but no significant detrimental effects on high-speed force production (think jumping). Only when a static stretch was held for more than 60 seconds was a moderate decrease is speed, power and strength noted.
In addition to being interested in the findings themselves, I was also interested in the authors inclusion criteria for review, as well as their theories explaining the wide variety of findings in previous studies. The selection criteria for this systematic review included “randomized or quasi-randomized controlled trials and intervention-based trials published in peer-reviewed scientific journals examining the effect of an acute static stretch intervention on maximal muscle performance.” The studies also needed to meet the PEDro inclusion criteria: 1) the comparison of at least 2 interventions, 2) interventions were currently part of physiotherapy practice, 3) interventions were applied to human subjects, 4) there was a randomization of interventions, and 5) the article was a full article published in a peer-reviewed journal. Study validity was also evaluated.
After all of these criteria were applied, the authors ended up reviewing 106 studies. When all of the studies were examined, it appeared that the results agreed with previous suggestions of static stretching decreasing maximal muscle performance. However, if you look at the duration of the stretch, the studies showed the difference in the dose of stretching (how long you hold it) and the subsequent effect on performance.
The authors’ theories regarding why such a wide variety of results are noted primarily revolve around the variation in the duration of stretches. The authors also found a great deal of studies that did not show validity for various reasons-mostly just poor execution of study design.
So what does all of this mean? Basically, that your last excuse for not stretching is seriously in question! So stretch away.