Hi alophysio, I think you are playing the devils advocate as I do not think that there are any such studies. Perhaps we are researching what the benefit is from pre exercise stretching.

Maybe it is mental focus, proprioceptive awareness, joint movement "preparation". Maybe the hype in the mind that you are about to exercise releases some central chemicals related to activity? Maybe it helps the individual "let go" of stored muscle tension, which is not actually a lengthening of a muscle and so is difficult to measure.

I think there might be evidence that warm-up can assist injury prevention. It is just the how that appears to be the thing we are missing. Any thoughts?8o