For most runners, when they're training for a marathon training program, or an Ironman the period of growth is usually about three weeks. 

You take a period where you are increasing your activity, then you back off and start increasing again from a lower point, to allow yourself to recover fully and decrease your risk of sustaining an overtraining injury.

You should do a similar thing when you are recovering from a running injury, but that period can be much shorter because your increases are happening during a period where you're actually healing and recovering from a running injury. 

Today on the Doc On the Run Podcast, we're talking about periodization in recovery and healing running injuries.