Let’s suppose you have been following your training plan loyally and are excited about getting to the starting line of the big race fit and healthy. With one fell swoop you become sick or injured and require time off from training to rest and rehab. Now, without getting into the particulars of your illness or injury, let’s suppose you are feeling well enough to begin training, or your physical therapist has given you the green light to start running again. Where to begin? Do you pick up in your training where you left off? Do you build back up to the point before you were forced to stop? The answers to these questions have a lot to do with how much time you needed to take off, your conditioning level before stopping and how many weeks remaining before the marathon.
Despite what many runners believe, de-conditioning is a process that takes several weeks to occur, so being forced to take a few days off (one week or less) may be of benefit to you as it will allow your body to rest without any negative effects on your conditioning. It is when down time gets beyond two weeks that your conditioning will begin to decay (gradually) and will require an additional week or two (or more) of recovery training to get back to the point from where you originally stopped.
In his book, Advanced Marathoning, Olympic marathoner and exercise physiologist, Pete Pfitzinger discusses the variables that go into deciding how to pick up where you left off. If the number of days missed is less than 10, then you can resume your running schedule regardless of when you left and how close the marathon is. If you missed more than 10 days, then you can resume your schedule if you have 8 weeks or more remaining. However, you will need to revise your goal if there are 8 weeks or less until race day. If you’ve had to be out for 3 weeks or more, then you will need to revise your racing goal regardless of how much time is remaining. It is important to realize that it takes approximately 4 weeks for a training effect to occur, which means 4 weeks of consistent running in order to begin to receive the benefits of those runs.
As a rough guideline, if you are out for one week or less, it is usually recommended that you begin running again at about 75% of the volume indicated by your training schedule, then resume normal mileage after. If you are out for up to two weeks, begin at about 50% of current volume for the first week, then 75% for the second week, and then resume normal training. Any time off which is greater than three weeks will require more modifications regardless of how many weeks are left remaining before the marathon. I would put a caveat to this return schedule in that if you are coming back from an injury and have been under the care of a physical therapist, the PT should be the one to decide the best course of action in returning to running related activities.
All the best!