Why is ice used to treat sport injuries? I would like a medical explaination.?

Question

I know icing can reduce swelling? But how does it work(medically)? Also, what other benefits are there from icing and for how long should it be done?

Answer 1

Icing should be done for twenty minutes every two hours for the first 24 hours following an injury.
Icing works by contracting the blood vessels and tissues involved in the injury allowing less plasma to collect thus decreasing swelling and minimizing further injury.

Answer 2

The cold stops inflammation.