That is the question. Researchers at Florida State University may have an answer.
Ten trained male runners participated in the study. On separate occasions, they ran for one hour on a treadmill, beginning with 30 minutes at a moderate pace and ending with a 30-minute performance test wherein the runners were instructed to cover as much distance as possible. The runners performed 16 minutes of static stretch for the major muscle groups of the lower body before one of the runs and just sat around for 16 minutes before the other.
The results? When the runners didn’t stretch they ran farther and burned fewer calories in the process. Stretching reduced efficiency! Turns out, runners’ legs are like shock absorbers; stiffer ones work better, helping the body recapture energy with each foot fall.
Stretching may slow me down by 3.4%, but I don’t plan on giving it up anytime soon. For me it’s not a matter of maximum efficiency (I don’t mind burning the extra calories). It’s a matter of injury prevention.
Updated December 2, 2009: See also this New York Times article on a study at Nebraska Wesleyan University with similar results: tighter muscles performed more efficiently than loose ones. (Via Kathy, on dailymile)
Personally, I stretch very little... Although I am blessed with unusual flexibility to begin with. But I've never been able to correlate stretching (or lack thereof) to injuries... If anything, I get injured less often when I don't stretch.
I'm a convert of not stretching (mostly). After reading a few critical arguments of stretching, and observing that many elite ultrarunners I know don't stretch, I changed my own beliefs from being an avid stretcher. I no longer stretch preemptively to prevent injury, instead I do a good warm up which I've read is far more effective at preventing injuries (and the stretching on cold muscles may actually harm them). I now only stretch to alleviate stress from an injury or potential injury.
I stretch just enough to not feel tight (usually 1-2 mins) before a run and a light stretch afterwards.
I only stretch if I have tightness in a certain area. I personally have not benefited from flexibilty stretching (static stretches). However, my body responds very well to light jogging / skipping pre-workout (dynamic stretching). Everyone's body responds differently so I'm a big believer to try something (not half ass) and if it's not beneficial, then don't do it for the sake of doing it. Why add unproductive activity to your training if you don't benefit from it?
My own stretching routine is pretty brief, actually. I used to stretch for ten minutes or so, but now I just do a few minutes. I've found it helps my first few miles go smoother... those miles in turn get me warmed up for the rest of the run.
In HS I stretched before I ran. I was never injured. In college I only did active stretching (warm ups) and I was always injured. But I was doing sprint workouts, not distance. That probably makes a big difference.
I stretch before and after, but I'm only doing about 10 minutes at the most. Now I'm scared that I've made the wrong choice about stretching. lol
Not going to give up stretch. I have to stretch as part of my warm up for running and TaeKwonDo.
I never stretch before a run, but I do stretch afterwards. I have chronic IT band issues, and the stretching helps quite a bit. Like most of us, I run a warmup before a race or hard workout, and might do a few drills (high knees, strides, etc).