Healing, sports improvement, immunity, body building and health maintenance takes place on several levels, and requires movement on those levels. Mechanical movement is body movement, and facilitates movement at the tissue (macroscopic) and cellular (microscopic). Exercise is great for movement at a mechanical level. But it can be supplemented with deep tissue massage to increase movement of fluids and nutrients at the tissue and cellular levels.
In order to have healing, immunity…, there must be a movement of fluids and nutrients into the tissues and cells for anabolism, metabolism, and catabolism,. And for this to happen, toxins/waste products need to get out of the tissue/cells.
A lot of massage techniques are for relaxation, which is healing in and of itself. But deep tissue massage is designed specifically to get into the deep tissue and facilitate movement of fluids/nutrients into the tissues and cells, and waste/toxins out of the cells, and thus facilitating general health, immunity, body building, and healing.