Thursday, February 21, 2013

How Fast Do You Lose It?

I'm finally doing serious running back outside again after three long weeks off my feet or on treadmills. While I knew that I wasn't going to be able to jump right back into where I was after my kick-ass January base blast (119 miles in 17 hours), I've been surprised how much perceived effort it's taken to run the last two days. I did 6.4 in 51:45 today and it wiped me out! So I was curious: just how quickly do you lose your fitness when you stop or reduce your training schedule?

Pete Pfitzinger, in a article first published in the Running Times, notes that your fitness level doesn't degrade as quickly as you might fear:
"...most elements of your fitness go down at about the same rate at which they go up....Between 1 and 2 weeks off from training, however, the benefits of recovery start to become outweighed by a loss in fitness. Although not many studies have measured loss of performance in runners after several weeks of detraining (would you volunteer?), performance is likely to decrease by about 3-5% after 3 to 4 weeks of detraining. A 40-minute 10K runner could expect to slow down by about 1 to 2 minutes after a 3 week break."
One surprising fact: it's the intensity of training rather than the volume that affects fitness maintenance:
"If you cut back the volume of your training (i.e. how often you train or how far you run), you can maintain your fitness level for a surprisingly long time. Studies have found that when either the frequency or duration of training are reduced (while the intensity of training is maintained) that aerobic conditioning is maintained for up to 15 weeks. When the intensity of training is reduced (while the volume of training is maintained), however, then aerobic fitness declines more quickly. If you must reduce your training volume, therefore, maintaining your training intensity is the key to maintaining your running performance."
So i'm not going to worry too much. After all, I did average 8:06/mi today, which is close to my standard pace. I'm thinking that after a few more runs I should be right back into the swing of things, even if i'm not sure i'll be able to get that nice shiny new PR I was hoping for in the Half of Quincy (just three weeks away!)


  1. Interesting post, Todd. I'm surprised/impressed by how many studies there are on the effects of detraining. A key takeaway for me is that the fitness losses that occur in the first few weeks of detraining are largely in the cardiorespiratory, rather than the muscular, system. What this suggests to me is that if an injury or other issue prevents me from being able to run for a few weeks, I can minimize mylosses by engaging in some other form or aerobic exercise, whether it be swimming, a bicycle, a rowing machine, or whatever. (However, if a break from running lasts several weeks, I'll also start to lose your running muscles, so its unlikely I'll be able to pick back up where you left off.)

  2. The focus on cardio over muscle is what I got out of it too, Joel, although whatever other aerobic exercise you do is supposed to be at the same intensity level as your running in order to keep your fitness at the same level. So the challenge is that the other activity will most likely challenge your muscles as they are working in ways that they are not used to. For example, I used the elliptical machine one day and while it was a great cardio workout, my thighs were sore for 2-3 days afterwards since they were not accustomed to that style of workout. I imagine this is why swimming is such a popular cross training exercise for runners; you can get a great cardio workout even if you're not swimming very quickly.

  3. Good info. As Todd says, it's important to do nothing new in the taper phase. So if it's x-training that you're used to, should be OK.

  4. came across this today, on the same topic:

    provides a bit of a different point of view than P.P; specifically, that it takes twice as long to gain as to lose fitness.