If your injury keeps you out of running for a week, you should be able to get right back to your training without losing any ground. But after a week of not training, you'll start to lose your fitness. But don't let fear of deconditioning make you start running again before you're healed. If you're still feeling pain after a week of rest and other self-treatment, it's a good idea to get your injury checked out by a doctor or physical therapist.
Cross-train Instead of RunningWhile you're resting your injury, cross-training is one way you can help maintain your fitness. You should only do activities that are pain-free. If you're under a doctor or physical therapist's care, make sure you check with him or her about safe activities. Biking and swimming are excellent aerobic exercises that keep you off your feet but still give you a good workout. Deep water running, also known as aqua jogging, may be the best cross-training activity during an injury-related hiatus from running. Your doctor or PT will most likely recommend strengthening exercises, since many running injuries are a result of muscle weaknesses or imbalances.
Even if you're cross-training on a regular basis, you're bound to lose at least some fitness after a break from running, since you won't be working your main running muscles as hard as you would when running. A general rule of thumb is that it takes about two weeks of training to come back from every week of no exercise.
Ease Back into RunningGo easy when you first return to running because if you run too hard, you risk re-injuring yourself. If you've been out of your running shoes for only a week or two, start at about half the distance you were running before your injury. You should be able to build back to your former level in two to four weeks.
If you've been out for more than two weeks, you should ease back into it. Start off with run/walking, alternating between intervals of running and walking. As you build endurance, you'll be able to extend the amount of time that you run and reduce your walking time.
More: How to Start Running Again After a Long Break
Dealing With the Emotional ImpactWhen you're recovering from a running injury, you become very aware of how running is a huge part of your life. You'll likely feel more stressed, since running is a stress reliever for many people. Try not to adopt a "woe-is-me" attitude. An optimistic outlook can help speed up your recovery. Follow these tips to help cope with the psychological strain of not being able to run.
The silver lining of any injury is that you'll appreciate being healthy and running comfortably much more when you come back. But be realistic in your goals and expectations and take the necessary recovery time. I've seen many runners start running again when their injury isn't quite healed and they end up re-injuring themselves. Be smart and patient and you'll soon be back to your previous running form.