Study finds limits of human endurance

Fascinating study reported on the BBC today. Long term energy balance trends to 2.5 x BMR which indicates that this is the upper limited for long term training loads.

BBC article I think there must be a typo given it says a standalone marathon is 15.6 x BMR which sounds ridiculous.

1 Like

on my reading list - thanks

Interesting study.

I’m not sure I agree entirely with the BBC summary, given the assumptions made in the study. No barriers have been found, in fact no barriers have even been tested in the study. This is a statistical trend only, surely?

Nordic skiers and TdF cyclists buck that trend at 3-5x BMR

I’m also not sure that cyclists are on a break in between major tours.

Also, regarding the TdF analysis:

“While neither group exceeded the apparent SusMS ceiling (Fig. 1A), it is unclear whether their above-average energy intake reflects special nutritional strategies (e.g., infusing glucose intravenously) or individual biological variation. Second, the signaling mechanisms linking energy imbalance to the body’s central regulation of activity, and that ultimately prevent humans from exceeding the observed SusMS versus duration curve, remain unknown.

The chart in the study shows that it trends towards (and under) 3 the longer the event goes on. I think even the TdF is too short and so 3-5 seems about right.

Again the study itself talks through some theories as to what physiologically may be causing this limit. The gut/bloody systems ability to transport is either limited or decreases in capacity during prolonged periods of stress. This is all my relatively limited understanding.

1 Like

Even if true it’s not like my training approaches that. I get a few days a week in the final months that I burn an additional 4,000Cal so a peak of ~3.5xbmr , but mostly iirc 2000 and I get off days.

If Strava is to be believed my Lanza effort was about 900Cal + 4000Cal +3500Cal so 8400 plus base burned in a day, so about 10000Cal or 6xbmr.

  1. Strava shouldn’t be believed - it’s a massive liar.
  2. Plus the other moving you did that day plus actual BMR. Probably takes it closer to 7.5 - well within the normal expected values.

Shows you that the 50-50-50 is really quite remarkable has to be close to what is possible.