Sustaining an injury during a workout can sideline your fitness efforts. But how do you know how to soothe the pain and help your body recover as quickly as possible? First, it's important to understand what kind of injury is bothering you. Acute injuries are ones that have a quick onset - they occur immediately or within hours of the activity. You'll feel pain, tenderness, swelling or inflammation, and your skin may be warm to the touch. Chronic injuries are those that are slow to develop. Pain may come and go, or it may flare up only after activity. If you just sustained an injury, then it's best to treat with ice first to reduce swelling and inflammation. Ice limits internal bleeding at the injury site as well. Chronic injuries respond well to cold therapy post-workout, too, although it doesn't help to ice before a workout. Apply ice or ice packs - frozen peas work well because they conform to the shape of the body - for 10 to 15 minutes at a time. Ice another time if desired, but allow the skin to return to normal temperature first. On the other hand, heat works wonders for sore and stiff muscles or joint pain. Heat therapy is effective pre-workout to increase elasticity in joints and muscles and to stimulate blood flow. Heat should never be applied post-workout to either an acute or chronic injury. Moist heat does the best job for muscles, so use a hot, wet towel or special athletic hot pack. If your injury doesn't improve within a day or two or the pain is excruciating, then see the doctor.