I have heard many times that stretching decreases strength, power, etc. To what extent does stretching effect a decrease in muscular ability and is it only for a time after stretching or permanent and why does this happen? Is it because stretched muscles still have the same ability to contract through their range of motion but because that range is bigger can output less strengths at individual points or what?

Just do dynamic stretching instead of static stretching.

http://www.nytimes.com/2008/11/02/sp...112pewarm.html

about 3 years ago, a poster in this forum opened my eyes to the stretching controversy.
That is one of the better lessons I have taken out of Totse RY.
Now , for 3 years, I've been ahead of the curve about this issue.
This year, it seems, the popular press is finally writing about it, though the word is just starting to get out.
The answer to the original question is, I believe:
your performance in a sprint or strength event will be diminished by stretching before the event.
I don't believe the negative effect will last more than 24 hours.
However, if your event is karate or gymnastics, etc, you probably will benefit from stretching prior to the event.

I think if you're taking part in a sport where you have to be explosive, a nice warm up to loosen you up a bit beforehand will do the trick. However I belive when you're training stretching is important otherwise you could pull you're muscles.

And what's emerging from research, it seems, is that stretching doesn't help prevent muscle pulls.

Then what does prevent muscles getting pulled. When I stretch out before boxing training I never seem to pull muscles, whereas if I don't stretch out properly I tend to pull one of my muscles.

I guess in your case , stretching helps?
though, you may have pulled those muscles on that day anyway.
There is research that shows stretching before maximal efforts results in lower max efforts.
And other research that shows injuries still occur at the same rate they would if one didn't stretch.
In other words, injuries happen and time spent stretching before an event is now considered wasted time.
Before an event it's now recommended to warm up well with large muscle movement, and if you're going to stretch, do it after the workout.

I know it goes against logic not to stretch, but you're going to see more and more press about this in the future.

Interesting. You're right that I could have pulled those muscles anyway. At training we go running then do the stretch out afterwards then continue with training. Perhaps it's something to do with the relaxing effects of streching after the warm up then continuing with training that helps.

I think it is important to remember that correlation does not necessarily mean causation. Sick people have more white blood cells but white blood cells do not make you sick. I haven't stretched statically in years simply because it doesn't feel right to me. There are a lot of movements that stretch out your muscles and warm up your body without holding yourself in an awkward, tiresome position for 20 seconds.

I'd bet that all these scientific studies only focus on static stretching when isolated by itself. An ideal warm up consists of light cardio, dynamic stretching, and then static stretching. I would like to see the same studies done under these circumstances. Just because it does harm on its own doesn't mean that it is an inheritanly harmful act.

Or maybe it is who knows

Yeah, for years the word was always hold a stretch and any dynamic/ballistic stretch was wrong.

Over time, if studies like you suggest are done, the suggested warm-up/stretch may change.

I think the main take-home presently is that going out to the track to run and immediately doing a cold calf stretch and hamstring stretch etc. are now frowned upon.