If you're injured and can't run, you won't lose fitness if you're idle for a couple days. If you're going to be off running for a week or more, add some other form of aerobic activity and you'll maintain the fitness you've built up. Your legs may feel sore when you resume running but you'll stay relatively fit. Warm-up before stretching . Use cold water over your legs after a run .
Cold water helps the legs recover quicker - just like putting ice over an injury.
In the summer, simply running the garden hose over the legs for a couple minutes will do the trick. Alternately, get in the shower and and run the cold water over your legs. Soak your legs in a hot bath with Epsom Salts regularly . This is great way to stop injuries before they happen. Epsom salts have magnesium in them which can draw inflammation out of the muscles.