Stretching Before Exercising Weakens Muscles

Khemisty writes "Back in grade school you were probably taught the importance of warm-up exercises, and it's likely you've continued with pretty much the same routine ever since. Science, however, has moved on. Researchers now believe that some of the more entrenched elements of many athletes' warm-up regimens are not only a waste of time but are actually bad for you. The old presumption that holding a stretch for 20 to 30 seconds — known as static stretching — primes muscles for a workout is dead wrong. It actually weakens them. In a recent study conducted at the University of Nevada, athletes generated less force from their leg muscles after static stretching than they did after not stretching at all. Other studies have found that this stretching decreases muscle strength by as much as 30 percent. Also, stretching one leg's muscles can reduce strength in the other leg as well, probably because the central nervous system rebels against the movements."

Comments

Importance of warm-up

[moro_666]

Back in the days when i was in school, warm-ups were there to avoid injuries, not to increase your performance.

By making your muscles weaker, the chance to get an injury decreases as well. People have proved over time (and quite many times) that you are able to hurt yourself with the strength of your muscles alone (ever seen those 100m sprinters falling like bricks on half way ?).

Re:Importance of warm-up

[Chees0rz]

I have been practicing this methodology for a while now. My highschool and college track coaches (and the assistants coming in) have preached Dynamic stretching (stretching through movement). So you do things like skipping, leg swings, high knee running, and a whole bunch of crazy things. It gets the muscles ready to move- not increase flexibility.


Increasing flexibility is for after the workout, where you hold a stretch for 20-30 seconds (for muscle memory).
Maybe I have drank too much of the koolaid, but I assume this is what the article is talking about. It's been around for a while (at least 8 years).

Re:Importance of warm-up

[fyngyrz]

The 30 second stretches are for after your workout, during the "cooling off" period.

That may be adequate for running, but it won't do for regimens with extreme range of motion, such as martial arts. We stretch for half an hour prior to a workout punctuated with short one-minute warm-ups every five minutes or so, and it definitely reduces injuries (which, as the GP has it, is the intent... not for "strength"... in fact, I've never heard — anywhere — that the act of stretching increases strength for the immediately succeeding session of exercise. I've been teaching martial arts for over twenty years.)

I can also tell you that if your body isn't prepared to reach an extended position, and it has to go there, either because you forced it to or someone else did, you had better have stretched first and be warmed up.

As for this line in TFS: "The old presumption that holding a stretch for 20 to 30 seconds -- known as static stretching -- primes muscles for a workout is dead wrong. It actually weakens them", the science of this has been known for many years. What happens is that the working elements of the muscle fibers are laid against each other in pairs with an intervening layer between; the more overlap, the more power can be generated because the overlapping surface area of the layer between is where the work gets done. When fibers are stretched, there is less overlap, hence the muscle can generate less power, but the muscle is longer.

Think of your forearm extended, and look at your bicep... see how it is long? Lots of fiber layers have slid against each other and now have considerably less overlap. Now move your arm to the 90 degree position at the elbow, and look at your bicep; it's bunched up, even if it isn't tense: many fiber layers are now slid to an overlapping position.

The number of fibers involved is the factor that determines the total amount of strength in your motion; high recruitment of fibers results in a strong motion, low recruitment results in a weak motion. We train to develop the ability to generate high recruitment on demand. But no matter the recruitment, if you start from a highly non-overlapped position, eg a stretched one, you'll generate less power with the stretched muscle.

This is the basis for moves like arm locks; if the arm is extended, not only is the leverage at the joint reduced, making it more difficult to close the arm against the lock, but the muscle is extended by the lock so that fiber overlap is minimal, which reduces the amount of force that can be generated by the muscle — it is literally a "double-whammy", and accounts for why a fully executed lock is so hard to exit using direct force (correct exits involve rotation of the arm or the lock itself in order to effect closure of the joint, and a good lock prevents such rotation.)

For any motion, you typically will have two muscle groups involved; the agonist, which is the muscle doing the work, and an antagonist, which is the muscle that would be responsible to reverse the motion. In the case of bending at the elbow, to close the arm, the bicep is the agonist and the triceps is the antagonist. If you are trying to open your arm, that is, extend your forearm, then the roles are reversed: The triceps is the agonist and the bicep is the antagonist. One of the key elements of controlling the force your body can generate is learning to really relax the antagonist, and again, stretching helps by teaching you what a really relaxed and extended muscle feels like; it is difficult to minimize fiber recruitment if you don't know what it feels like and the muscle isn't accustomed to that condition.

Anyway, my recommendation is that athletes ignore this report entirely; stretching significantly increases your range of motion, particularly in your ankles, legs, groin, waist, wrists, fingers, back, neck and shoulders, and to the degree that your sport requires (or risks) large range o

Re:Importance of warm-up

[Anonymous Coward]

I think this entire article is a load of attention seeking BS, and I will not believe a word of it until I see a proper peer-reviewed research paper in a medical journal that debunks stretching.

How about these:
Nelson AG, Kokkonen J, Arnall DA: Acute muscle stretching inhibits muscle strength endurance performance. J Strength Cond Res. 2005 May;19(2):338-43

Power K, Behm D, Cahill F, Carroll M, Young W: An acute bout of static stretching: effects on force and jumping performance. Med Sci Sports Exerc.2004 Aug;36(8):1389-96

Cramer JT, Housh TJ, Weir JP, Johnson GO, Coburn JW, Beck TW: The acute effects of static stretching on peak torque, mean power output, electromyography, and mechanomyography. Eur J Appl Physiol. 2005 Mar;93(5-6):530-9. Epub 2004 Dec 15

Fletcher IM, Jones B: The effect of different warm-up stretch protocols on 20 meter sprint performance in trained rugby union players. J Strength Cond Res. 2004 Nov;18(4):885-8

This is not exactly news. The studies have been showing these same results for years now.

Re:Importance of warm-up

[mopomi]

How could you possibly make your claim that

There is absolutely no evidence that stretching before exercise weakens muscles (note I used the exact same phrase as the title) so long as you don't over do it.

if you haven't actually read any peer-reviewed articles about it?! You do know about scholar.google.com, right? It's not that hard to check on the people interviewed in the NYTimes article. There are many papers on the subject. Yes, there is still work to be done to answer all the questions, but your ridiculous statement that there is absolutely no evidence that stretching (static) before exercise weakens muscles just shows that you haven't bothered to read about it.

Here's your spoon-fed google search with links to a few abstracts for your edification.

http://www.acsm-msse.org/pt/re/msse/abstract.00005768-200403000-00004.htm;jsessionid=JJgJGzgYVCy4qyLKzfW21kXYSGvYP3tWmM2WDyC6Nr1nvvvH7ykd!-1853705402!181195629!8091!-1

http://eric.ed.gov/ERICWebPortal/contentdelivery/servlet/ERICServlet?accno=ED448119 [PDF]

http://www.ncbi.nlm.nih.gov/pubmed/9368275

http://www.bmj.com/cgi/content/abridged/325/7362/468

http://www3.interscience.wiley.com/journal/119251161/abstract?CRETRY=1&SRETRY=0

http://www.cjsportsmed.com/pt/re/cjsm/abstract.00042752-200409000-00004.htm;jsessionid=JJgpcrQvSRyyCn1CG2XnW4WS6vzdsmrXnhG43kmLDT1CyhhCknr9!1600976923!181195628!8091!-1

http://apt.allenpress.com/perlserv/?request=get-abstract&doi=10.1519%2F1533-4287(2001)015%5B0098%3AAEOSAN%5D2.0.CO%3B2

Re:Importance of warm-up

[ShadeOfBlue]

Actually, when they talk about the acute effects of stretching, they're talking about the immediate effects.

That is, weakened muscles are an acute effect because the effect only lasts ~30 minutes. Acute does not mean they stretched the bajeezus out of a muscle before the test.

Furthermore, you still seem to be having trouble grasping the difference between stretching, static stretching, and warming up.

Note to self: read linked articles before posting!

[K3ba]

Most of the negative comment posters below obviously didn't take the time to read the linked article.

Some types of stretching are good, some are bad. The article explains the differences quite well and still recommends that some stretching takes place...

Please RTFA

[Timothy Brownawell]

TFA is not saying that warm-ups are bad, it actually says that they're good. What it does say, is that just stretching is not a proper warm-up. A proper warm-up has light exercise to make you, well, warm. It also says that "stretch and hold" is bad, but exaggerated movements ("dynamic stretching") are good.

I've got your peer-reiviewed papers right here

[Ambitwistor]

I think this entire article is a load of attention seeking BS, and I will not believe a word of it until I see a proper peer-reviewed research paper in a medical journal that debunks stretching.

Geeze. I've noticed a certain hyper-skepticism among Slashdotters. Please note that the New York Times is not known for trumping up pseudoscience with no support in the literature.

Others have responded that the article is not "debunking stretching", just pointing out problems with certain kinds of stretching. And at least one other poster gave references, some of whom involved people interviewed for TFA. More specifically with respect to the studies mentioned in TFA:

The article cites Duane Knudson, a kinesiology professor at CSU. Peer reviewed research paper.

The article mentions a Las Vegas stretching study. Peer reviewed research paper.

The article mentions Malachy McHugh, a researcher in NYC. Peer reviewed research paper.

The article mentions a collegiate volleyball study. Peer reviewed research paper.

And so on.