A big problem when you injure yourself is that commonly your muscles will go into spasm to protect the area of damage.
However the spasm will reduce blood supply in the area ironically where you actually need mor blood to flow to help repair the damage.
In addition as the blood supply to the damaged area is reduced an accumulation of metabolic waste and inflammatory substances occurs; causing even more pain.
We need to increase blood supply and flush the area fo damage with fresh blood oxygen and nutrients.
Once the pain is reduced then the relevant rehabilitation can be undertaken.