text: sore legs? yesterday i ran 3 miles and my legs were fine if a bit tired today the back of the lower part of my legs started hurting is this normal? im a teenager btw yes that is normal... did you warm up before you did? stretching and preparation is important, and many coaches and trainers do not express that enough... elevate your legs and lie down and try to relax, that will help with the pain you are experiencing..