One of the common phrases that is tossed about in amateur athletics is RICE. It stands for Rest, Ice, Compression and Elevation, i.e. what you should do in response to an injury.
While the command for Ice and Compression is fairly straightforward, the concepts of Rest and Elevation require a little more understanding of the healing process.
Rest is what the doctor always recommends. Yet many believe their concern over potential liability is what produces such a conservative prescription. If the doctor tells you not to do anything, then you can't further injure yourself, and he can't be held liable.
Ultimately it is exercise that will allow an injured player to recover and rebuild his or her strength to pre-injury levels. Injured athletes need to find ways to exercise sooner IF they want to heal sooner.
Ice can play a role. Applying ice during light exercise will reduce the discomfort, and keep swelling and inflammation under control. If exercise hurts, don't do it. But if it is just uncomfortable, using ice may be the answer.
Similarly, the conventional wisdom is to Elevate an injury after it happens. But once again it is exercise that will heal it. If possible move on an injury with ice in place. The best example of this is an ankle sprain. Applying ice as quickly as possible is still the best response.
But instead of sitting on the sidelines with the ice in place and elevating the foot, walking (if possible), with ice on it to control the swelling and inflammation, will reduce the possibility that the ankle will "stiffen" up. The result is that the athlete will be able to return to play sooner.