What Scientific Studies have to Say about Static Stretching

What Scientific Studies have to Say about Static Stretching

Honestly, I don’t follow a stretching program. I might stretch every now and then after an easy five to six mile run when my quads or hamstrings feel tight but even then I keep it quick and light. I’ve just never made the commitment to stretch and frankly I’ve been concerned that I might be setting myself up for an injury or hurting my performance. As it turns out a majority of the scientific evidence indicates that I’m fine and there’s no evidence that static stretching is beneficial for preventing injury and there’s a possibility that stretching just before a long run may actually hurt performance.

This is static stretching that I’m talking about, stretching performed while at rest in which the muscle is gradually stretched to the point of discomfort and held for 30 seconds or more — all that routines we used to do in gym class. Static stretching should only be performed after a warm-up or post-run and should never be performed when your muscles are cold. Let me also point out that there’s growing evidence that dynamic stretching, stretching using active muscular effort in which the end position is not held, is beneficial. While I’m going to stick to the topic of static stretching I will mention dynamic stretching briefly in this article and I promise to expand on it in future articles.

Prior to researching this article I’d read a lot about the benefits of static stretching from running websites, books and magazines. The common wisdom is that stretching needs to be part of a good running plan and that the few extra minutes spent each time you go out would pay off in reduced muscle soreness, improved performance and a reduction in the likelihood of injury. As a non-stretcher I wanted to know how these claims held up under medical and scientific scrutiny. So, I explored each of these three common claims one at a time, the results of what I found out make up the bulk of this article.

Reduced Soreness

Delayed Onset Muscle Soreness (DOMS) is the term used to describe the soreness experienced after strenuous or unaccustomed exercise. The pain associated with DOMS usually peaks a day or two after exercise and can last up to five or six days. I reviewed a number of studies that looked at how stretching before or after running impacted the pain associated with DOMS. In general the scientific studies report that “no significant differences were found, regarding any of the parameters, when comparing stretched and nonstretched legs” and that “preexercise static stretching has no preventive effect on the muscular soreness, tenderness and force loss that follows heavy eccentric exercise.” One report from went as far as to state that “similar bouts of static and ballistic stretching induce significant increases in DOMS”, that’s right, stretching actually increased soreness. A systematic review of ten studies performed in 2008 reported that “The evidence derived from mainly laboratory-based studies of stretching indicate that muscle stretching does not reduce delayed-onset muscle soreness in young healthy adults.”

The evidence is pretty clear, static stretching does not help with muscle soreness. I’m also sorry to tell you that in general there’s really nothing that you can do that will prevent, reduce or cure the pain associated with DOMS, it’s one of those things that you have to suffer through along with the rest of us. I’ve always taken DOMS to be a good pain, an indication that I’m making progress – “no-pain, no-gain.”

Improved Performance

I think we’re all looking for ways to improve our running performance. Personally I’m slower than I’d like to be, I’m a middle of the pack runner and while I’m not looking to set any records or even win my age bracket I’d would like place in the top 25-30%. I was very curious if stretching could help give me an extra edge and save 10-15 seconds off me pace. As I’ve alluded to the studies show that there’s no performance benefit from stretching, and at least one study has shown that static stretching can hurt performance of endurance events. A study from The Florida State University released in September 2010 reports that “findings suggest that stretching before an endurance event may lower endurance performance and increase the energy cost of running” and goes on to say “Performance was significantly greater in the nonstretching vs. the stretching condition.”, another study, designed to look at the effects of stretching on vertical jumping (VJ), found that “Despite no adverse effect on VJ, stretching did cause a decrease in lower-extremity power.” Finally a systematic review of 23 articles published in 2004 showed “no evidence that [static stretching] improves running economy”.

While there’s no performance benefit as a result of static stretching and it may actually hurt performance there is growing evidence that a commitment to a dynamic stretching program can improve performance over time (a little more on this later and definitely another article in the near future).

Injury Avoidance

Let’s look at the final claim, injury avoidance, the one claim that I’m sure keeps most people stretching. Nobody wants to be laid-up because they didn’t bother to stretch. So, what does the evidence show? In a report from the CDC published in 2004 the findings show that “There is not sufficient evidence to endorse or discontinue routine stretching before or after exercise to prevent injury among competitive or recreational athletes. Further research, especially well-conducted randomized controlled trials, is urgently needed to determine the proper role of stretching in sports.” Back in 2004, the CDC said there wasn’t enough evidence that stretching played a positive role in injury prevention. They went further by saying that more injuries would be prevented by improved warm-ups, strength training and balance exercises, than by stretching. Another study, one of the largest ever, published in August 2010 on the USA Track and Field website, found no risk or benefit of stretching on injury rates from the almost 1400 volunteers who participated in the study. The report stated that “Over a three-month period there was no statistically significant difference in injury risk between the pre-run stretching and non-stretching groups.” Injury rates, defined as an impairment that prevented running for 3 or more days, were around 16% for each group. It’s important to note that there did seem to be an impact on injury rates as a result of a change of routine, so if you stretch now you should keep it up (read the study for more info).

The studies show that just like the impact on performance and soreness, there seems to be no benefit of static stretching on injury avoidance, when performed before running.

Conclusion

The evidence is clear that static stretching offers no real benefit to runners and while it may increase pain associated with DOMS and have a somewhat negative impact on performance during endurance events, there is also no real harm in a pre-run or post-run stretch either as long as a warm-up is performed fist. But generally the time spent performing static stretches would be better spent on some other beneficial activity. This is good news for me, I’m going to continue my standard no-stretch routine but now I won’t worry about constraining my performance or risking injury.

Alternatives

The good news is that my research has also revealed things that you can do to improve performance and reduce your risk of injury; unfortunately, there’s still no good way to minimize the pain resulting from DOMS. The three main supplemental routines that I came across that can help running performance and reduce injury potential are warming-up/cooling-down, weight training and dynamic stretching, specifically active-isolated stretching. I know I told you not to stretch but this is a different type of stretching, active-isolated stretching can be performed as a warm-up and doesn’t put the same type of strain on muscles as static stretching does. In addition you can get much of the benefits of active-isolated stretching even if it’s performed at a different time of day, like while you’re watching TV just prior to going to bed. I’ll write more about this topic in the future, after I’ve had a chance to learn more about its pros and cons.

A good warm-up and cool-down, 5-10 minutes of light activity, have been shown to be beneficial in preventing injury and improving performance. Warm-ups gets blood flowing to the muscles and the heart, preparing them for more vigorous activity, and the good cool down helps the heart and muscles to slow down gradually, helping with removal of metabolic wastes.

Most of the weight training studies indicated an improvement in running performance as a result of leg strength training. One such 8 week study showed a correlation in the performance of half-squat leg exercises and improved running speed and endurance in well-trained adults. However, a study published in October 2010 showed “no benefits of an 8-week concurrent strength training for running economy and coordination of recreational marathon runners despite a clear improvement in leg strength, maybe because of an insufficient sample size or a short intervention period.” It looks like we’ll need to see the results of some longer-term studies to get a definitive answer, for now, I’d recommend incorporating strength training as a way to improve running performance.

As a final note I’d like to suggest that the best way to prevent injury, improve performance and avoid soreness is to listen to your body, take a rest days as needed, hit the treadmill, pavement or trail and mix things up a bit. To prevent injury, increase your training over a long period of time and invest in some good shoes. If you’re in pain stop running give your body time to heal, seek medical advice if the pain is severe doesn’t go away after a day or two. To improve your speed you need to improve your conditioning and put in the time, do intervals, speed work, and hills and make strength and cross training part of your routine. And, above all else have some fun, it’s ok to challenge yourself but nobody said it has to be torture.

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