I have been exercising regularly for about 2 years and completed my first half Ironman earlier this year. I am currently recovering from ACL injury (from recreational basketball game). It has been about 3 weeks since surgery and I can put some weight on it again. I am told that rehab will be about 3-4 months.

Maybe I can start swimming again relatively soon but expect it will be at least a few months before I can do most of what I was accustomed to.

I know my VO2 max will fall (it probably already has to some degree) but how large of a decrease in VO2 max is expected during recovery?

1 Answer 1


The negative effect on VO2max due to detraining varies a bit with different studies, with losses ranging from 4-14% when training is stopped for less than 4 weeks [1-8]. Obviously, the longer the inactivity, the more the negative impact on VO2max., to a point. For example one study found that endurance athletes lost 7% of their VO2max in the first 21 days of inactivity and eventually stabilized at a 16% loss after 56 days (1).

A different study found that over a 2400 meter run, women averaged 21 seconds slower following 15 days of inactivity. [18]

The better trained you were before the inactivity (higher trained-state VO2max), the bigger its decline when training is stopped (1).

You can find the references in the following link Link

  • 1
    You should take care when formatting your answers. You cut and paste from the link you provided. That gives the appearance that you are providing the information. I'd suggest that you edit your post to enclose the copied information in quotes to avoid any confusion as to the origin of the studies.
    – rrirower
    Commented May 25, 2016 at 13:17

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