Good News About Detraining: It’s not as bad or as fast as you think

By Jason Koop,
Head Coach of CTS Ultrarunning

One of my coaching principles is to ‘coach the person first’. The main message of that philosophy is to treat athletes as people first. Their athletic endeavors, whether finishing their first 100-mile race or nabbing their next belt buckle, are all part of the equation but do not constitute the whole enchilada. Even in normal times, being the soccer coach, parent, small business owner, father, mother and a host of other personas require time, energy and attention. And to be quite frank, more often than not those roles take precedence. All of us, even the elites of the elite, are people before we are athletes.

With training schedules interrupted, trail access and outdoor activities restricted, chaos on the home front (homeschool and work from home anyone?), keeping the proverbial ship afloat and headed in the right direction is a feat in itself. In this context, training is understandably a lower priority in terms of how people are directing their energy. However, running should remain important, even if that importance has changed from ‘optimizing fitness’ to anchoring some semblance of normalcy. And that’s fine.

The fear of detraining is causing anxiety for some athletes. You’ve worked hard for your fitness and, by golly, no trail closures and rescheduled Zoom meetings are going take that away. This fear leads to irrational decisions, even in normal times. We train when we’re sick, when we’re injured and when every fiber in our body is telling us that the next workout will do more harm than good. Yet, we soldier on, all in the name of not losing what we’ve gained. The science tells us, though, it is hard to lose much more than a few percent of your fitness. And if we’ve learned anything in the last few weeks, it’s that we should listen to the science.

How detraining works

To understand how detraining works, first it is important to understand how the timecourse of training works, since detraining is nearly the inverse. If you have been running for more than several years, and if you can remember way back when you started running, this universal sequence of events inevitably unfolded:

  • It’s really hard at first. You feel like a giraffe on roller skates. Everything hurts and is awkward but these sensations only last for a few weeks.
  • The awkwardness is gone. You are stronger and improve rapidly for a few years. Along the way, you set every Strava PR within a 10-mile radius. Nothing can stop you.
  • All of the sudden, ‘WTF?’. Workouts and races are stuck in a rut. Improvements are marginal and you might set a PR on a net downhill course if you are lucky and if you get a tailwind. You blame age, circumstance and the new shoes you just paid $200 for because they lack carbon fiber springs.

Fitness progression follows a curvilinear path. It looks like the simple graph below that I have stylized from the relevant research. And for almost everyone, that non-linear path is relatively universal, as we can only withstand training progression at a certain rate (you can’t go from running 0 miles per week to 100 miles per week in one week). Early on, you will improve more as a matter of coming from nothing than from the most brilliantly designed workout you think is making an impact. Later down the road as your physiology becomes more and more optimized, the improvements you seek are harder to identify. They are also more difficult to achieve, a point I always reinforce to our coaches when touting their athletes’ improvements. Correct training structure and efficacious coaching matter more the more experienced the athlete.

Figure 1-How training works

Detraining is the inverse. No matter how ‘intense’ your detraining is (going from 100 miles per week to 0 in one week), the effect it has on your fitness is more marked at first, and then become subtle later. We see this across specific physiological parameters (cardiac output, VO2max, speed at lactate threshold and metabolic enzymes) as well as performance as a whole (measured in time trials or time to exhaustion tests). Gradually, that performance decline levels off.


Figure 2- How detraining works

Unlike the seeming universal shape of the training curve, the deleterious shape of the detraining curve can be affected by a number of factors that determine the velocity and absolute degree of detraining that will occur.

  • Experience of the athlete. The more hours and years of training you have under your belt, the more resistant you are to detraining. Fortunately, most ultrarunners have experience in spades.
  • How much and what type training you were doing before the inflection point.
  • What your training looks like after the inflection point.

Of all of these, you can control point number 3 (most of the time, at least). In today’s everchanging world, it’s reasonable to assume that your training is going to have to change and that your fitness is going to take a hit. In fact, some recent straw poll data from researcher Stephen Seiler has indicated that endurance athletes on average are decreasing their training volume 1.3 hours per week, but within that data, the athletes who were training >12 hours per week indicated that their longest of long activities (aka the ultrarunning staple) are the ones that are being affected the most.

What decreased training means for you

If research on detraining has taught coaches and athletes anything, it’s that a little goes a long way. While complete training cessation (meaning zero training) for several weeks can result in performance declines of >20%, adding in as few as three sessions (~50% training reduction) per week can keep those losses in the 5-10% range, even if the detraining phase is several weeks in length. Meaning, if you cut your training in half, you are only going to pay a single digit penalty for it. Furthermore, your return to your previous fitness will not take all that long. I’ve run some theoretical examples below based on athletes that have to take 10%, 50% and 70% off of the table based on synthesizing the relevant research in this area.


Figure 3-Detraining sceanrios

In any of these cases where some minute form of training exists, the hypothetical athlete would be able to return to normal levels of fitness within a few or several weeks.

Free Ultrarunning Training Assessment Quiz

Take our free 2-minute quiz to discover how effective your training is and get recommendations for how you can improve.

The take home

Don’t be afraid of losing your fitness at this time. Times are chaotic and we’re settling into a new temporary norm, as oxymoronic as that sounds. If you do decide to take some training off of the table, whether from overall volume or the frequency of your runs, don’t be afraid. Detraining to any significant extent is harder to achieve than you might expect. It takes complete training cessation for several weeks to make a meaningful impact. If you are crunched for time, lacking motivation for the longest of long runs, quarantined to your house or have some other sort of restriction where your volume is going to be pinched, it’ll be OK. If you can, incorporate (but do not increase) shorter, high intensity workouts as a way to further flatten the detraining curve. The daily workouts we are posting in the quarantine project are effective, time efficient solutions even for the most time crunched of schedules. Most of all though, keep some level of training and activity. Be a person first and realize your role as an athlete can come further down the line. Focus on the runs and workouts that will make you a better you. They ultimately will make you a better athlete, just in due time.


Bosquet, Laurent & Mujika, I. (2012). Detraining.

Coyle, E. F., et al. “Effects of Detraining on Cardiovascular Responses to Exercise: Role of Blood Volume.” Journal of Applied Physiology, vol. 60, no. 1, Jan. 1986, pp. 95–99., doi:10.1152/jappl.1986.60.1.95.

Lacour, J.r., and C. Denis. “Detraining Effects on Aerobic Capacity.” Medicine and Sport Science Physiological Chemistry of Training and Detraining, pp. 230–237., doi:10.1159/000408790.

Mujika, Inigo, and Sabino Padilla. “Detraining: Loss of Training-Induced Physiological and Performance Adaptations. Part I.” Sports Medicine, vol. 30, no. 2, 2000, pp. 79–87., doi:10.2165/00007256-200030020-00002.

Enjoying This Article? Get More Free Running Training Tips

Get our coaches' best training advice, delivered straight to your inbox weekly. 

This field is for validation purposes and should be left unchanged.


Mujika, Inigo, and Sabino Padilla. “Detraining: Loss of Training-Induced Physiological and Performance Adaptations. Part II.” Sports Medicine, vol. 30, no. 3, 2000, pp. 145–154., doi:10.2165/00007256-200030030-00001.

Neufer, P. Darrell. “The Effect of Detraining and Reduced Training on the Physiological Adaptations to Aerobic Exercise Training.” Sports Medicine, vol. 8, no. 5, 1989, pp. 302–321., doi:10.2165/00007256-198908050-00004.

Pallarés, Jesús & Sánchez-Medina, Luis & Pérez, Carlos & Izquierdo-Gabarren, Mikel & Izquierdo, Mikel. (2009). Physiological Effects of Tapering and Detraining In World-Class Kayakers. Medicine and science in sports and exercise. 42. 1209-14. 10.1249/MSS.0b013e3181c9228c.

“Detraining (Reversibility).” Encyclopedia of Sports Medicine, doi:10.4135/9781412961165.n140.

Bosquet, Laurent & Mujika, I. (2012). Detraining.

Comments 15

  1. Pingback: Creating a Successful Off-Season or Transition Phase for Ultrarunners - Jason Koop

  2. Pingback: The Cyclists’ Ultimate Holiday Nutrition Guide - CTS

  3. Pingback: Masters and Grand Masters: Avoid These Cycling Training Mistakes - Chris Carmichael

  4. Pingback: How to Ride Faster at Your Favorite Repeat Cycling Events - Chris Carmichael

  5. Pingback: 6 STEPS TO RIDE FASTER » CyclingSmarter

  6. Pingback: 6 Steps to Go Faster in the Same Bike Race Next Year - Chris Carmichael

  7. Pingback: Trail Running Daily News | Wuesday Mar 8 - Yeovil Marathon

  8. Pingback: Missed Workouts: Simple Guide to Adjusting Training - Chris Carmichael

  9. Pingback: The Best Way to Return-to-Training Following Some Time Off - Jason Koop

  10. Pingback: Reconnect to Your WHY to Reinvigorate Your Runs - Jason Koop

  11. Pingback: CTS Position Statement on Coaching and Training During the COVID19 Pandemic - CTS

  12. Pingback: There is No Quarantine on Mental Training for Athletes - Jason Koop

  13. Pingback: Trail Running Daily News | Wuesday Mar 8 |

Leave a Reply

Your email address will not be published. Required fields are marked *