Agree icing is best immediately after the strain or injury to reduce the swelling. After swelling has dissipated I find the heat very useful in loosening tight muscles. As I understand it heat is good for blood flow and that greatly increases healing of the torn muscles. After a broken wrist the heat was also useful to loosen tissue to recover movement of atrophied tissue from being in a cast. Any way I sometimes take doctors advise with a grain of salt and use what works for me. Of course it may not work for others.

jimmyb