Has this happened to anybody? I am a reasonably fit guy who has been running, weight-training, yadda yadda for years. I tried out Tabata sprints a la Mark Sisson's Primal workout a week ago and really liked them. Post-sprints, my quads were a little tender, understandably. I did my regular workouts through the rest of the week, nothing special; quads a little tender still but nothing prohibitive. Comes this Saturday morning, I jog out to my sprint mark, crouch down and as soon as I begin to push off, BLAM! Both quads felt like someone had shredded them. I hobbled home like I'd run a marathon. I was able to do a regular cardio workout, though. The rest of my leg muscles were fine. I hadn't stretched before I started to run, but I just can't believe such unbelievable pain could come from simply being a little tight. Right now, one hour later, quads are still sore, but I can move around fine. Anybody have a similar experience?