I've gotten into cycling recently. I'm not in great shape and I'm terrible at running. I've noticed that when I've been riding for a while and stand up, my right leg will involuntarily twitch causing my foot to quickly rotate up and down on the pedal. I thought this might because I'm just not used to exercising so much, but once when I had a close call with a car, both of my legs were doing this uncontrollably for nearly 10 minutes! I was only a little shaken up but I couldn't stop them from shaking. I stopped for a few minutes to try and walk it off and then I was fine. Has anyone ever experienced this?