These acids are formed when the glycogen stored in the liver and muscles is burned to produce the energy expended during exercise. The acids must eventually be reconverted to glycogen and stored again, or drained out via the lymph and circulatory systems. Pain and fatigue persists until this process of reconverting or excreting is completed. Massage can help eliminate the irritation caused by these wastes, thus increasing muscle recovery rates. For example, this is why boxers are massaged rather than rested between rounds.
Joints are critical to exercise because joints are moved by the muscles to produce movement.
All joints are complicated, and their parts have a way of settling and stiffening when not used. A sluggish, numbed feeling in the joints discourages exercise. A massage therapist counteracts this by using massage strokes and passive movement to release the muscle tension and free the connective tissue found around the joints that could bind the joints. Massage also aids recovery from soft tissue injuries such as sprains and strains. This is possible because the growth and repair of tissue are accelerated by efficient circulation in the injured areas and appropriate stimulation of the healing tissues.