Scientific study: What happens if you take 12 weeks off from running...... After 2 weeks, your VO2 max will drop by xx percent.

rojo wrote:

Go ahead and guess.

Come on.

Give it a try.

Answer: 7%. "The two-week break in running shows signs of training regression, enzyme levels in your blood that are associated with endurance performance decline by 50 per cent and VO2 max drops by seven per cent."

https://runningmagazine.ca/sections/training/how-long-does-it-take-to-get-out-of-running-shape/

You said XX%, so I thought that it was a two-digit number (i.e., 12%). I guessed 10%, the lowest possible value.

In college we used to take between 7-12 completely off from physical activity at the end of XC season to “reset”. Used to feel like an absolute chump on the first run back after 2 weeks. Makes you remember why everyone who doesn’t run says running sucks.

But funny enough you’re back in the saddle just as quickly. I wonder if they can do a follow up study to see how quickly you regain the lost VO2 and fitness. A 7% loss is a lot less than I would expect. The article’s point about the most rapid loss occurring in the early stage and most the damage being done by the 1 month mark is interesting but makes a lot of sense.

In conclusion, keep running. If you cant run, then stay active how you can and be consistent about it. Dont take off 12 weeks!

*7-12 days

For the record my guess was about 15-20%.

in the past few years, i run every day. Though it is interesting.

I will try it.

I'd like to see a study with cross training (eg bike, elliptical) instead of rest. My guess is it would be closer to 1%.

I wish I had Daniels running formula in front of me... If someone else has it handy, they should take a look at the training breaks chapter and post his table for VDOT values. If I'm remembering correctly, he would agree that you lose that top end fitness pretty quickly, but then it really plateaus and even with a super long break, you only lose like 20%

Oppenheimer wrote:

I'd like to see a study with cross training (eg bike, elliptical) instead of rest. My guess is it would be closer to 1%.

Daniels Running Formula Chapter on Training Breaks has a comparison between running economy lost when cross training vs pure rest. Not a study exactly, but written by someone who's done plenty of studies.

That study would have been a heck of a lot more useful if they had continued to follow each athlete to see how long it took them to get back to the same previous performance level.

There's enzyme loss, hemoglobin loss, red blood cell loss, but capillary density takes a long long time to build back.

Two weeks off would probably not significantly affect capillary density but two months would.

n=7? Wow, that's some impressive research.

How much you gain back fitness also depends on the endurance base you had before the break.

And also, even after 3 months, or even a few years of non-activity, someone who was a very good endurance athlete will improve way faster than someone who never run in his life. Maybe due to "muscle memory" or something ?

The Dallas bed rest study (1966) had only five subjects and is considered a canonical experiment.

IIRC, one of its findings was that Vo2Max of modestly trained people tends to be very responsive to training stimulus/bed rest, and changes in hemoglobin mass explain only a fraction of the improvement/decline, which were faster and larger than changes in Hb mass. E.g. Vo2Max fell by 27 % in three weeks during bed rest whereas Hb mass likely fell only modestly in that short of a time.

Aragon wrote:

The Dallas bed rest study (1966) had only five subjects and is considered a canonical experiment.

IIRC, one of its findings was that Vo2Max of modestly trained people tends to be very responsive to training stimulus/bed rest, and changes in hemoglobin mass explain only a fraction of the improvement/decline, which were faster and larger than changes in Hb mass. E.g. Vo2Max fell by 27 % in three weeks during bed rest whereas Hb mass likely fell only modestly in that short of a time.

That doesn't make sense.

more is more wrote:

That study would have been a heck of a lot more useful if they had continued to follow each athlete to see how long it took them to get back to the same previous performance level.

There's enzyme loss, hemoglobin loss, red blood cell loss, but capillary density takes a long long time to build back.

Two weeks off would probably not significantly affect capillary density but two months would.

So what do you think happens to those capillaries? Do they just disappear?

umm, what? wrote:

That doesn't make sense.

It actually does.

Because Hb mass indeed changes relatively slowly, it is not unlikely that Vo2Max of better-trained athletes is replenished relatively quickly after a brief detraining period.

Aragon wrote:

umm, what? wrote:

That doesn't make sense.

It actually does.

Because Hb mass indeed changes relatively slowly, it is not unlikely that Vo2Max of better-trained athletes is replenished relatively quickly after a brief detraining period.

Your VO2 peak, in absolute terms isn't going to fall. Your metabolism doesn't work like that.

You will certainly lose endurance during a detraining period, but these issues get confused by people trying to explain the changes without reference to metabolism.

umm, what? wrote:

Aragon wrote:

It actually does.

Because Hb mass indeed changes relatively slowly, it is not unlikely that Vo2Max of better-trained athletes is replenished relatively quickly after a brief detraining period.

Your VO2 peak, in absolute terms isn't going to fall. Your metabolism doesn't work like that.

You will certainly lose endurance during a detraining period, but these issues get confused by people trying to explain the changes without reference to metabolism.

Apparently Vo2Peak in absolute terms did fall, becuase in the Dallas bed rest study, the average Vo2Max of the subjects fell from 3.3 l/min to 2.4 l/min after three weeks of total untraining, almost totally explained by the fall in stroke volume.