How Detraining Works and 3 Steps to Avoid It


Coaching is almost entirely about motivating and inspiring athletes, and there are a number of ways to accomplish that. Personally, we prefer to emphasize the positive by inspiring athletes to achieve lofty goals. Sometimes, however, athletes respond better to the desire to avoid negative consequences, like losing power, gaining weight, and getting slower. So, as we enter the period of the year when North American turns cold and dark, this is a good time to talk about what actually happens when you let your bike collect more dust than miles.

Detraining, or the reversal of physiological adaptations that were the result of training, starts quickly and progresses rapidly. Short periods of inactivity are relatively easy to compensate for, and are in fact beneficial for athletes for recuperation, but after about two weeks the impact of not riding your bike gets progressively more detrimental.

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As you sit on the couch and your bike hangs dormant in your garage, here’s what’s going on in your body:

Within 2-7 Days: Your blood plasma volume starts dropping, reducing the water compartment of your blood. This means you’re losing the adaptation that helps keep stroke volume high and provides fluid for temperature control (sweating). The amount of glycogen – the storage form of carbohydrate – your muscles can store starts to decrease as well. Consistent training is a signal to your muscles to maximize their glycogen storage capacity, and to your cardiovascular system to maintain high blood plasma volume. These adaptations start declining quickly, but can also return quickly when you start training regularly again.

Between 2-4 Weeks: This is the timeframe where you lose a lot of hard-earned fitness. Over the first four weeks of detraining VO2 max can decline between 4-14%, and initially that’s mostly due to a reduction in maximum cardiac output (remember that reduction in blood plasma volume?). You see this when you experience higher-than-normal exercise heart rates after a few weeks of minimal exercise. After the first three weeks or so, a decrease in your ability to extract oxygen from the blood also contributes to the reduction in VO2 max.

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That decreased ability to pull oxygen from the blood is indicative of two other changes caused by a lack of exercise. After 3-4 weeks you see about a 3% decrease in red blood cell mass, which reduces oxygen carrying capacity. This is natural because your body adjusts red cell mass to your demand for oxygen; lower activity levels mean you can get all the oxygen you need from fewer red blood cells.

Your body also adjusts to the shift in resource demand with changes inside your muscle cells. Mitochondria are essentially the powerplants of your muscle cells, and they process carbohydrate, fat, and lactate into usable energy. One of the most important adaptations to endurance training is an increase in the size and number of mitochondria; and within 3-4 weeks of minimal training you start losing that adaptation. To make matters worse, the drop-off is greatest in the endurance-oriented slow-twitch muscle fibers, whereas your fast-twitch fibers retain their mitochondrial activity for longer.

Does Experience Matter?

Athletes often ask whether the 20 years of cycling they have in their legs changes the way they adapt to training and detraining. The answer is yes, experience matters. Take the detraining-related losses of mitochondrial volume and power at lactate threshold. Compared to sedentary people and novice endurance athletes, after 8-12 weeks of minimal exercise an experienced but detrained athlete will still have 50% greater mitochondrial volume and higher power at lactate threshold. There’s also evidence that the capillary density that enables well-trained athletes to deliver oxygen to working muscle cells faster reduces from its peak density but remains elevated compared to non-athletes.

Steps to Avoiding Detraining

The way I see it, fitness has momentum. It takes time to create the adaptations that make you stronger and faster, and you can ‘coast’ through a short period of zero training before losing that momentum. But as you know from riding your bike, maintaining momentum requires less effort than gaining it, and the same is true with fitness. Holding on to what you have is easier than you may think, and it’s certainly easier than starting over.

  • Step 1: Reduce frequency. You can reduce your number of weekly rides by about 30%, which means a rider can go from riding 6 days a week to 4 days, or 4 days to 3.
  • Step 2: Reduce volume. For most people this goes hand-in-hand with reducing frequency, but the point is that you don’t have to make your rides longer in order to compensate for reduced frequency.
  • Step 3: Maintain or increase intensity. This is the critical part. You have to give your body a reason to keep your performance markers from falling, and intense efforts provide the stimulus necessary. That doesn’t mean you have to do 3-4 days of structured VO2 max intervals every week to keep from detraining; I’d recommend 1-2 interval workouts, one longer endurance ride with some strong climbing efforts, and one fun and hard group ride. And the biggest take-away here is that lollygagging along isn’t going to do you any favors if you’re already experiencing reduced training frequency and volume.
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To return to my preferred method of positive reinforcement, the opportunities here are that you can avoid a significant drop in performance pretty easily, even with the Holiday-induced travel craziness, and that you can make big performance gains year-on-year by continuing to train through the winter. You’ll see a smaller reduction from your peak in-season performance, and that means you’ll have a bigger and stronger foundation to build on for next season. If you want to be stronger in 2014 than you were in 2013, now is the time when you lay the foundations for those improvements.

Chris Carmichael
CEO/Head Coach of CTS
Originally Published in Road Bike Action Magazine

Comments 15

  1. Nice post!!! I already saw a lot of questions about cross-training, using weight training and running, I use to ride 4/5 times per week, I`m intended to switch to 2 bikes + 1 run… and increase weight training.

    Looking forward to read something about these compensations.

    Thanks Chris!

  2. I love training indoors during the winter. I much prefer using the time to get fitter rather than worry about losing fitness.

    Key is having a really good training environment, I have a virtual reality setup using a Cycelops Power Beam + their Virtual Training offering (others are available). Every day I can ride a different route and travel the world. Many of the climbs I have done in reality and with the right equipment doing them in my house feels very close to the real thing. Add to that a “virtual partner” with your own or other PBs to race agains + online races with other users and its np to maintain motivation and intensity.

    I’ll be aiming to maintain around 100 TSS/d. Just a couple of examples from this week
    – Yesterday I climbed Mount Ventoux in tempo mode, then did some hard FTP intervals
    – Tomorrow, after a rest day, I plan on trying to beat my PB up Mount Palomar and get under an hour.
    All in the comfort of my own home listening to music turned up to max and no risk of bad weather or punctures.

  3. What about those of us transitioning from on sport to another with the change of seasons? I am a pro snowboard racer and prepping to get on snow but still riding my bike here in Colorado (did hill intervals yesterday) until the lifts start running again (hoping next week!) and what should I do in between? I would think I should be tapering a bit on the bike to have fresh legs for the snow, but since I work so hard to build power in my legs on the bike that transfers to the snow will I loose fitness? I ride the trainer only to maintain during the winter finding the best way to stay in shape for snowboarding is to snowboard! I ride 4/5 days a week 4/5 hours a day (lift rides my only rest- no sitting in the lodge) either free riding or running gates. Every spring I find I can hit the bike pretty hard thanks to all that snowboarding and I know all the interval work gives me repeatable power on snow, they go well together. Thanks!

  4. thank you.. great article… i already passed it to my riding friends..our group rides have dwindled and i needed to create guilt… we are on the edge of winter here,,,,

  5. So if you switch over to another cardio sport such as running, hiking, x-skiing, etc. for the winter, does that also help you keep your fitness benefits such as keeping your blood plasma levels and your VO2 max closer, if not at where you want them?

  6. Thanks Chris
    What are your thoughts on base endurance training over the winter? Going slower to go faster when the new season starts….Longer aerobic rides at a lower heart rate. Many thanks

  7. I am a novice, on my fourth year riding, and older, at 62. This winter I am using your trainer dvds two to three times a week. Is this good enough? I also do group rides twice a week through the winter along with the dvds.

    1. hey larry i am a novice as well at 49yrs old. i have been riding to CTS Dvd’s for the past 6-7 winters…they work amazing for a great strong start in the spring..i keep track of my numbers on a specific outdoor ride/route to measure my results at the beginning and end of each season and i have only gotten stronger over those years..

      3 times a week i have a friend or two come at around 7:00am to train in the basement with me.. sometimes there are 3 people down there. Big screen TV and once we get into the middle of the winter we turn the sound off on the DVD’s and blast some good tunes.. its a ritual and we often poke fun at the coaches on the tapes,,some of the things they say,, ect.. to pass the time! ha ha. our favorite line is “Where there is a wheel there is a way”..but seriously though.. the coaching / things said during the efforts i find to be really valuable… everything about stressing aero positions / learning to produce power in a tuck position to physiological explanations.. its a education as much as it is a work out… and maybe the next best thing to having a coach..

      i have about 10 of their DVD’s…we get the most advantage from the: Time Trial power interval, cadence and Fitness,,(which is a generalized program with a range of different types of efforts..) having a commitment with friends (and wife) to ride with really really helps with consistency…

  8. the one thing that makes it hard for me is riding in the Colorado winter. I attempt to compensate by working out on a treadmill and elliptical. I do not enjoy riding below 40 degrees outside but I do try to get back on the bike as quickly as the spring will allow me.

  9. How often can we integrate a bonk or depletion ride? In other words, going on a ride (1 hour) with out calories intake except maybe a cup of coffee? thanks guys your tips are great!!!

  10. well… I don’t think I have to worry about detraining… I’m a CTS athlete… and I trust my AWESOME Coach to kick my a** ALL WINTER LONG!!! I’ve been a CTS athlete for a year and a half now… my gains have been tremendous… and I can’t imagine ever NOT having a CTS Coach!! Thanks, Chris!!! 🙂

  11. Chris,
    How dose cross training play a role in this?
    I am running and weight training with one or two spin class’s and for the first time off my bike 3 years since August with hopes that my head and body come around in January for a good 2015 season.
    Thanks again for all the great motivation emails every year.
    Matt squier

  12. Well, that explains it! I went out with my hard group ride last Saturday after being off the bike for two weeks. My heart rate was higher than it had ever been! I am taking your well timed advice and continuing with some winter training. Thanks for the motivation Chris.

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