Why Do My Muscles Get Sore When I Play Ball in the Spring?
They do this because you have probably not been exercising the particular muscles which you employ in throwing a ball enough in the winter to keep you in good condition. Muscles which have been developed through use or work need more work to keep them in condition. In a sense certain of the muscles which you employ in playing ball have been treated during the winter very much as if you had tied them down, as we suggested you might do with your arm. You have not been using them—they have not been doing enough work, and they begin to lose their strength when for any period they have not been used enough. The soreness that you feel is the natural condition that arises when you begin to use a muscle that has been idle for some time.