When a muscle goes into spasm, it tends to close off its own blood drainage due to pressure on the veins. This causes an accumulation of the normal waste products created by the muscles, including lactic and acid build-up. By putting direct pressure in those areas of greatest concentration of lactic acid by means of trigger point therapy, the lactic acid and wastes are then reabsorbed back into the bloodstream and carried away for elimination. The muscle is then able to relax.