* Put an ice pack, or ice wrapped in a towel on the affected area for about 20 minutes. This should be done immediately.
* Stop and take rest for a while, making sure to raise the injured area above your 'heart level'. Obviously, if it's your back, you can't do that.
* Massage the area a few minutes and repeat this every hour. This will decrease swelling and increase blood flow.
* Try to apply a heat pad / hot water bottle immediately. If you don't have these things a *moist* hot towel, hot shower or even a moist hot sponge can do the trick. Do this only if the swelling decreases. Never use them for more than 25 minutes at a time.
* Compress the injury with an elastic bandage / gauze. Make sure you don't wrap it so tightly, as that will cut off circulation. Blue skin, tingling and numbness are dead giveaways.
* Start your activity slowly. Begin by doing some easy stretches, then move on to walking etc.