In the days following a strenuous workout, sore muscles and joints are common in men and women. The pain can last for as long as one week, but usually lasts only a few days. The soreness is the result of torn muscle fibers that become stiff once the body is inactive after a workout. Muscle soreness, while unpleasant, is a natural body response and a good indication that your last workout was effective. The after-effect of muscle soreness happens to athletes and beginners, and there are a number of ways to combat the problem, so your next workout isn’t a painful experience.