I seem to be having a problem lately where now that I'm not getting as much excersise, 8 hours a week of riding instead of 17-22 hours a week in the summer that after a few days of not riding, particularly after a race weekend my legs begin to hurt, it's not a sharp pain, it's a throbbing pain. Once I start to ride again the pain usually goes away, with the exception of the trainer, still get pain even on the trainer. It usually starts in my quads and my knees and then into the hamstrings. Is this just lactic acid buildup? Am I not stretching enough?