Stretching the truth: Can the benefits of stretching towards injury prevention be proven?

Title: The Impact of Stretching on Sports Injury Risk: A Systematic Review of the Literature

Researchers: THACKER, STEPHEN B.; GILCHRIST, JULIE; STROUP, DONNA F.; KIMSEY, C. DEXTER JR.

Summary: We conducted a systematic review to assess the evidence for the effectiveness of stretching as a tool to prevent injuries in sports and to make recommendations for research and prevention.

Methods: Without language limitations, we searched electronic data bases, including MEDLINE (1966–2002), Current Contents (1997–2002), Biomedical Collection (1993–1999), the Cochrane Library, and SPORTDiscus, and then identified citations from papers retrieved and contacted experts in the field. Meta-analysis was limited to randomized trials or cohort studies for interventions that included stretching. Studies were excluded that lacked controls, in which stretching could not be assessed independently, or where studies did not include subjects in sporting or fitness activities. One author screened all articles initially. Six of 361 identified articles compared stretching with other methods to prevent injury. Data were abstracted by one author and then reviewed independently by three others. Three authors using a previously standardized instrument assessed data quality independently, and reviewers met to reconcile substantive differences in interpretation. We calculated weighted pooled odds ratios based on an intention-to-treat analysis as well as subgroup analyses by quality score and study design.

Results: Stretching was not significantly associated with a reduction in total injuries and similar findings were seen in the subgroup analyses.

I felt this review paper was important because I feel the world’s exercise practices are steeped in tradition rather than actual knowledge of how the body responds to exercise and related practices such as stretching.

Basically this paper is a meta analysis. A meta analysis is simply a review off all the relevant research on a given question to find out if there is a consensus. The results of this review paper clearly demonstrated that there isn’t sufficient evidence to believe that stretching before exercise or sport prevents injuries. However, the research did indicate that stretching increases temporary flexibility. Well that makes sense doesn’t it? But once again, even increased flexibility has not been shown to prevent injuries. Not only that, but increased flexibility has actually been shown to decrease performance in more than one study.^1,2,3

One thing this paper brought out was that “warm-up”, rather than mere stretching, may indeed be useful in preventing injury. Warming up helps to increase the blood flow to muscle tissue, increase temperature of the tissue, and even increases range of motion.

Effective warm-up for weight lifting should include multiple reps on the exercise that is to be performed. Using about 50% of the maximum workload is generally effective for warm-up. Warm up for a given muscle group is not necessary after a work set has been performed. In other words, it is only necessary to warm up before your first set for a given muscle group.

Now I can hear many of you thinking, “I enjoy stretching. I don’t know if I want to stop stretching.” Please don’t misunderstand the purpose of this article. I don’t want people to stop stretching. All I want is for people to stop telling other people that stretching is required to prevent injury. There is no evidence to believe that stretching prevents injury and the ongoing belief and practice of stretching to prevent injury is just one more stumbling block preventing understanding and real progress in the practice of bodybuilding.

Stretching acts as a sort of primer or a pre-exercise ritual. It helps people get mentally prepared for maximum effort even if it doesn’t do much for the muscle itself. This is important and shouldn’t be abandoned simply because stretching adheres to the SAID principle (Specific Adaptation to Implied Demands) just like everything else. More detailed information on the use of “pre-exercise rituals” can be found HERE.

References

1. Cornwell, A., A. G. Nelson, G. D. Heise, and B. Sidaway. Acute effects of passive muscle stretching on vertical jump performance. J. Hum. Mov. Stud. 40: 307–324, 2001.

2. Knudson, D. V., P. Magnusson, and M. McHugh. Current issues in flexibility fitness. Pres. Council Phys. Fitness Sports 3: 1–6, 2000.

3. Kokkonen, J., A. G. Nelson, and A. Cornwell. Acute muscle stretching inhibits maximal strength performance. Res Q. Exerc. Sport 69: 411–415, 1998.