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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."
The "stretching reduces injury" canard has been disproven in study after study. Warming up may have some benefit, but stretching isn't the way to go if you're worried about injuries.
One study is at http://www.sportsinjurybulletin.com/archive/stretching-exercises.html
As it turned out, stretching during warm-up had no statistically significant effect on the risk of injury, either for soft-tissue problems or bony disorders...Although pre-exercise stretching was totally unimportant from an injury standpoint, other easy-to-determine factors actually did a decent job of prognosticating who would get hurt. For example, age was a good predictor of injury (the older the athlete, the higher the injury frequency)...In addition, 20-metre shuttle-run time was an outstanding predictor (the faster the time, the lower the risk of injury), a relationship which suggested that overall fitness -- not the presence or absence of pre-workout stretching -- had the paramount influence on injury occurrence
rage, rage against the dying of the light
The deleterious effect of static stretching on muscle power has been known for years.
It's not a matter of static stretching being "bad for you", what's "bad for you" depends on context. Static stretching is a developmental exercise. You wouldn't go to the weight room for serious strength training before a competition, and the same applies to static stretching.
Well coached athletes have been doing the kind of warm-up exercises described in the article for years, it's just that the word hasn't trickled down.
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When it comes to doing martial arts classes and other exercises, I typically start with some deep breathing for 1-3 mins (preferably while walking to the class), then follow with a light 50-60% warm up. I have stretched cold before exercise in the past, but it kept causing injuries (I obviously stopped doing that). Then after I finish a class I'll cool down with some stretches while my muscles are warm - which I find I can stretch much further.
I'm over 30 now and have recently re-started capoeira (so pretty hard for work me), and these high effort classes are getting much harder since I've been out of training for a few years. Getting back in to it I've found (casual observation, no science here ;-) that after a combination of a deep breathing and a light warm up, my ability to train is increased substantially. I'm not exaggerating at all. We're talking the difference between having to stop constantly and feeling like passing out, and carrying on a class just at the edge of my comfort zone. Most of the article seems to back this experience up with some science, which I'm glad about :-)
As a martial artist, I now only do dynamic stretches before practice or sparring. I stopped doing *static* stretches before I spar or work out because it made me slower. My stretching coach told me the same - do the splits and stuff afterward, and do range of motion stuff (like doing light stretch kicks until you build up to your maximum range) beforehand. This is also very important in Judo, where any leg stretches you do beforehand may make your footwork slower and hence make it easier to be thrown. Dynamic stretches also have the advantage of not slowing down your heart rate before your big event.