-- Marathon Running Information, Coaching and Advice from Coach Joe English

Training: Impact of time off on running performance

Coach Joe English

Coach Joe English

A reader that is in our armed forces sent in the following question to recently:

“I am training for a race on march 27th. i am in the army and unfortunately, my unit is going to be in the field from february 23- march 12 and i will not be able to do any running. Can you tell me how much this time off will affect my training and will i be able to regain much in the two weeks i will have when i get back before the race? if you could help me with this i would really appreciate it. Thank you.”

The question here is about the impact of taking time off from your training. There is some science here that allows us to predict what the impact will be from a training lay-off, but let’s get some basic facts together first before we jump in.

First, taking time off from training can be due to any number of reasons, whether it be due to an injury, an illness or just a busy work or travel schedule. In the case we’re talking about here, your running health is not involved and you know that you’ll be taking the time off. These are important considerations, because it means that you can plan for the time off and have an action plan once you return to running in the last few weeks before the race. Often an injury or illness will force a runner out of their training without warning and this leaves them without the chance to prepare. You’ll have the benefit of this foresight as you plan for your time off.

With that in mind, let’s think about the impact of time off of running for any reason. There will be two impacts: 1) a loss of some cardio-vascular fitness (your running efficiency) and 2) a loss of some muscular strength. Both systems in your body are impacted by the time you take off running.

The good news, again, is that you know about the upcoming lay-off, so it will be your job to get yourself as strong and as fit as possible before you take the time off. You will essentially want to be “ready” for your race before you take your break, and then use the time after the break to revive your muscle-memory and get the feel of the run back under you in the last couple of weeks.

What’s the impact of time off from running?
This brings us to the all-important question: how much are you going to lose in your cardio-vascular efficiency during the time that you take off. Research shows that our cardio-vascular fitness certainly does decline over time. There is almost no impact to taking up to one week off of running. After that, we decline fairly slowly over time. We runners FEEL like we lose more fitness, more quickly than we really do.

Running Coach Jack Daniels quotes some specific numbers in his book Daniel’s Running Formula“. He are some sample values in the loss of cardio-vascular fitness from his book:
Up to 5 days — no loss
7 days off — 0.6%
14 days off — 2.7%
21 days off — 4.8%
28 days off (one month) — 6.9%
56 days (two months) — 15.3%

You can see that the first two or three weeks do not see a huge loss in performance, but the impact gets great as time goes on.

What you can do with this data is plan for the loss in performance. In other words, if you are race ready at a particular pace and you are forced to take three weeks off, then you can adjust your race pace by about 5% and this should account for the loss in training time. This may turn out to be a conservative estimate in your case, if you make sure that you are fit and ready (meaning you have essentially completed your training) prior to your time off.

Once you get back to running in the last two weeks before the race, then focus on regaining your speed and strength. Try to get back to doing speed work and tempo work that will help you find your feel for running. In those last two weeks, try to get as much quality running time as possible and avoid “junk” workouts such as short, easy jogs.

Do you still have to taper?
The last question is do you still have to taper for your race as you normally would? Tapering is the period when we unwind ourselves from high-intensity training. In your case, your taper is essentially going to be the time that you take off. That will unwind you and help you recover from your training. This is again why it is important for you to get the your longest run distance before you take your time off. So when you restart your training in those last two weeks, just focus on speed and quality and then take the last couple of days off before the race. You will have taken all the rest that you need during the time off in the preceeding three weeks.

Good luck to you and let us know how it goes.

Coach Joe English, Portland Oregon, USA
Managing Editor, Running Advice and News


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