hamster

There are different aspects of "shape".

One aspect that responds really quickly is heart stroke volume. You _will_ see a decrease in stroke volume and a corresponding decrease in VO2max and in your power after as little as 10 days sitting on the couch.

However, it's easy to lose and easy to gain back. It is more or less maxxed out by about 2-3 months of doing regular intervals, even starting from low levels. That's the core idea behind periodization of training. You do long slow distance off-season, working on everything except your heart, and then you add speed and intervals just before you start racing.

There are other adaptations, like the ability to eliminate lactate and the density of mitochondria in the muscles, and those take longer to lose. At the extreme, your maximum sprint power can stay near original levels after 2 months of detraining.

I would say that the 1:3 rule is accurate for breaks in training above 5 days and up to 2-3 months. Beyond that, the ratio could be closer to 1:1.

Clipped_in

^^^^Nice post! What is "out of shape" is an excellent question.
I had a good year going last year, but had to go out of town for 3 weeks in August with no real exercise except for some light hiking and a little bit of time on a stationary at the hotel.
When I got back, I went for one of my favorite rides of about 50 miles that includes quite a bit of climbing, but nothing really steep. I absolutely scortched it on the ride doing it as fast and strong as I had ever done it. The catch; however, was in the recovery. The next day I was a lot more fatigued than normal after that ride. So in that cirucumstance, the being "out of shape" was my bodies ability to recover quickly. It took a couple of weeks of working hard and resting before I was back with the program.

VegasVic

First time back on the bike after more than a couple weeks off and it feels like I've never ridden before. Doesn't take long to get back into the swing of things though.

sced

Age makes a big difference in how long. Same with healing from injuries. At 56, some injuries never really go away...without surgery, and injuries you had in your teens come back to haunt with a vengeance. I could easily run a sub-5minute mile in my 20's and now I'd have to devote the rest of my life to getting under 7:-)

bikerjp

Agree about cross training but if I don't have the time to ride it's hard to find the time for other stuff. I have tried a few time to add in some running but I got injured. Maybe should just take it slower but not really a fan.

RT

Evidently my magic number lies between 1 and 16 days. This morning's ride sucked ass. Meant to get out two days ago, but winds were 40+ mph.

jbchybridrider 

I,ve just had 4 months off from an operation and I'm done finished and toast. It's a long road back to fitness from here.

hamster

There is a classic story about Greg Lemond. He had a near-fatal hunting accident (collapsed lung, lead pellets stuck in heart lining, and massive blood loss), which kept him off the bike for about 2 months. 6 months after the accident, he was competing in world-class events; after 10 months, he placed second out of 90 cyclists in one stage of the Tour of the Americas; and 2 years after the accident, he won Tour de France.

He was 25 and very fit at the time of the accident, so that had to have helped recovery. Still, it's a good example of what is achievable.

gregf83 

According to "Time course of loss of adaptations after stopping prolonged intense endurance training" there is a significant drop in the first 12 days, although the test on the 12th day seems to have limited the drop for the 21 day test.

hamster

That's VO2max, and VO2max is not the entire story.

This article looks interesting (but paywalled): https://www.ncbi.nlm.nih.gov/pubmed/10999420

"Resting muscle glycogen levels return to baseline, carbohydrate utilisation increases and the lactate threshold is lowered, although it remains above untrained values in the highly trained. At the muscle level, capillarisation, arterial-venous oxygen difference and oxidative enzyme activities decline in athletes and are completely reversed in recently trained individuals, contributing significantly to the long term loss in VO2max. Oxidative fibre proportion is decreased in endurance athletes, whereas it increases in strength athletes, whose fibre areas are significantly reduced. Force production declines slowly, and usually remains above control values for very long periods."

RT