Stretching is good for you.
There. I said it. Now lets get to the science.
There are piles and piles of research proving the inverse relationship between stretching and running performance. By and large these studies focus on a pre-event prolonged static stretching protocol. In english, this means that an athlete would hold a stretch for an extended period of time (typically 60 to 120 seconds) and then almost immediately after complete the testing protocol to check what the stretch(es) did to their performance. Well, their performance suffered.
But what about when the stretching is done separately from training and racing? Here, the analysis seems to suggest that stretching has at worst a neutral effect on athletic performance and quite possibly a positive effect. As usual, the vast majority of studies focus on various strength training, plyometric and strength training markers. Although a couple did relate directly to running.
The impacts for us slow twitch athletes is that we can, and should, include stretching in our training and recovery protocol. But said stretching should be done at a different time than we do cardio. For my coached athletes, Restorative Yoga is often scheduled on Sundays. For years this has been done out of practical necessity. Saturday is typically the hardest training day of the week since that is when most cycling and triathlon clubs do their long ride and Sunday is when many yoga studios (for reasons I’ll never totally understand) schedule their Restorative or Yin Yoga classes. It is a great fit – ruin your legs on Saturday then get a gentle stretch on Sunday as part of your active recovery. Nothing has changed in this recommendation for my triathletes. The only difference is that we have some science behind it now.
Shrier I. Does stretching improve performance? A systematic and critical review of the literature. Clin J Sport Med. 2004 Sept
Kallerud H, Gleeson N. Effectes of stretching on performances involving stretch-shortening cycles. Sports Med. 2013 Aug
Rubini, et al. The effects of stretching on strength performance. Sports M. 2007