Time Off: What Happens with Detraining?

What happens with 5 weeks of rest in elite riders?

TOOLBOX: The holidays, social events, winter weather, and less daylight are all good reasons for taking time off from training and kicking back a bit. But how does this time off, and detraining affect your cycling fitness?

Kicking Back

Stress + Rest = Growth can succinctly summarize any training theory. Indeed, this applies to everything in life too. We all need a break, whether it’s from the stress of training or the stress of work and everyday life. There’s no need to feel guilty for periodically reducing training or even taking a complete break.

Of course, for many of us, being fit is more than just about exercise. Being fit and exercising is wrapped up in our sense of identity, to the point that exercise itself can become an addiction. Besides anxiety, this can also lead to the other extreme of burnout, where all desire for exercise vanishes, sometimes permanently.

So we want a happy medium, where we structure breaks intelligently. This can be in the form of reduced training every few weeks, or it can be completely off the bike or with no exercise for a period of time at the end of the competitive season. What happens though if we go feral and take an extreme amount of time off?

Maldonado-Martin et al. 2017

While there has been a good amount of research on detraining, including one case study following Miguel Indurain 14 years after his retirement, there has not been a really systematic tracking of what happens physiologically to elite cyclists pre/post a prolonged period of complete cessation of exercise.

Maldonado-Martin et al. (2017) tested 10 elite U23 cyclists who were extremely fit (VO2max 78.5 mL/kg/min, 18-22h weekly training) at the end of competition season (September), and again after 5 weeks of complete training cessation in November. In between, the athletes performed no physical training and had no dietary control. Essentially, they were allowed to go feral!

The testing included:

  • Anthropometry (body mass, skinfold at six sites).
  • Blood was taken to measure red blood cell counts, haemoglobin, and haematocrit prior to exercise testing.
  • Graded exercise test to exhaustion (100 W start and increments of 35 W every 3 min). Wmax was calculated as the final power output, pro-rated in case they couldn’t complete all 3 min of a stage. Blood lactate was taken at each stage to calculate wattage at LT1 (increase of 1 mmol above baseline) and LT2 (4 mmol). VO2max was measured according to validated criteria.

Slamming the Brakes

So the researchers let the young elite cyclists go feral for 5 weeks. It’s understandable but unfortunately, they didn’t obtain records of their actual activity or diet. What did they find after the prolonged period of inactivity?

  • Body mass gain was surprisingly minor at 1.7 kg, and the sum of six skinfolds went up from 45.2 to 50.6 mm. So there was definitely some gain in fat mass and probably not that much muscle mass loss.
  • Red blood cell count (4.9 down to 4.6 106/mL) and haemoglobin content 14.9 down to 14.0 g/dL) both decreased. Haematocrit also decreased (43.0 to 41.7%) given the decrease in red blood cells.
  • We can see the decreases in test performance measures in the figure below. Note that the decreases were larger when normalized to body mass, showing that the weight gain had a disproportionate impact on the detraining response.

Sudden Stop

The study’s results are not surprising in that prolonged detraining negatively impacted every measure of fitness. What’s unique about the study is the relatively high fitness and racing level of the participants, and the prolonged period of presumably full detraining. This gives us a good insight into the actual magnitude of changes with detraining.

We see that VO2max dropped by about 8-11%, which is in line with the drop seen in elite athletes from other sports with similar detraining durations. The good news is that a lot of the drop is likely from decreased blood volume (decreases of ~6-7%). While it takes time for blood cell production to ramp up again with training, this is still a shorter recovery timeline than that required for structural changes to the heart and blood vessels.

One area of concern is that the decreases in power output at LT1 and LT2 were higher (12-15%) than those with VO2max. While VO2max is a good indicator of overall aerobic fitness, endurance capacity is often more determined by the ability to sustain a high percentage of VO2max.

What would be brilliant, of course, is further testing of these cyclists upon the resumption of training and over the whole year. This would help us see whether and how quickly they could return to “baseline.”

One other unknown is how much detraining goes on with less fit and masters level riders. It could be that we have a lower peak and therefore a lower drop. It could also be that we have a lower floor and a lower capacity to regain any lost fitness.


Personally, I wouldn’t recommend such a prolonged detraining period for most recreational level riders. Given that masters athletes take longer to recover from an individual hard effort, it is also most likely that we also take longer to recover lost fitness. If you are going to take time completely off, I would recommend not more than two weeks away from the bike. If possible, I would also pair this with some level of alternative activity rather than totally sitting on the couch.

As you read this, I’ll actually be on a planned 8-day training break to visit my parents in Vancouver for Chinese New Year. I’m not planning on any cycling or running, but will pack my climbing shoes because they’re so easy to pack in case I have the chance to get to a climbing gym. Otherwise, I’ll be doing a couple of brisk walks. Enjoy the time off. Remember, training breaks are as much for the mind as for the body!

Have fun and rest hard!


Maldonado-Martín S, Cámara J, James DVB, et al (2017) Effects of long-term training cessation in young top-level road cyclists. Journal of Sports Sciences 35:1396–1401. https://doi.org/10.1080/02640414.2016.1215502


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