3 ms·

You are confusing BMI with body fat percentage.

nordsieck 7y ago
> You are confusing BMI with body fat percentage. I understand that they are different things. Unless these are bizarrely jacked ultra-marathoners, BMI should work just fine.
- frickinLasers 7y ago
  For clarity, you could have just quoted the body fat percentages from the next couple sentences in the abstract. >> Mean (+/-SD) percent body fat values for men and women were 17+/-5 (range 5-35) and 21+/-6 (range 10-29) , and ranged from 6 to 14 and 14 to 27 among the fastest three men and women. I would imagine the fastest finishers are not "bizarrely jacked" (they usually look pretty scrawny), but their BMI is not very well correlated with their body fat percentage.
  - eredengrin 7y ago
    Also this line > We conclude that despite wide variations in BMI and percent body fat among ultramarathon participants, the faster men have lower percent body fat values than the slower men, and finishers have lower percent body fat values than non-finishers. So I do stand corrected that not all of them are significantly below 10% body fat, but some definitely were (I don't see a breakdown anywhere giving an indication of how many), including some of the top finishers. I'd also imagine the ones at higher percentages who performed well probably have higher floors to begin with for how little body fat they can reasonably reach. In any case, it is not at all abnormal for BMI to have nothing to do with body fat percentage or how jacked someone looks, especially with athletes. BMI is probably one of the most meaningless health metrics in common use.
  - dmix 7y ago
    Even further I'd imagine looking at the data for the top 30% of runners who are in the competitive tier this article is talking about would have more relevant and uniform data with narrower ranges.
- runamok 7y ago
  I've gone to ultras. You really need to have a range for the elites vs. everyone else. It's a very inclusive sport and you have participants that are fairly overweight even. Based on what I recall from my college track days where I knew my teammates' body fat percentages (4% to about 10%) I'd estinate that most elite men are at the lower end of that. Also because most men have more muscle mass their metabolic resting rate is higher so that definitely could be part of the reason why women and men peak performance is so close in ultras. They are using 10 to 15% more calories per hour I'd estimate. Also on a hilly course they need to tote that extra mass up a lot of extra climbs. I am surprised no one has mentioned Ann Trason that won 13 (iirc) Western States and used to win many ultras outright.
  - atomical 7y ago
    Elite athletes that can't manage their weight so that they have enough body fat to last until the end of the race? I think not. Also, extremely low body fat can cause a host of other issues like low testosterone that could effect race performance. It's a small sport with not much competition.
- Shorel 7y ago
  BMI is basically useless for people who exercise regularly.

> You are confusing BMI with body fat percentage. I understand that they are different things. Unless these are bizarrely jacked ultra-marathoners, BMI should work just fine.

frickinLasers 7y ago
For clarity, you could have just quoted the body fat percentages from the next couple sentences in the abstract. >> Mean (+/-SD) percent body fat values for men and women were 17+/-5 (range 5-35) and 21+/-6 (range 10-29) , and ranged from 6 to 14 and 14 to 27 among the fastest three men and women. I would imagine the fastest finishers are not "bizarrely jacked" (they usually look pretty scrawny), but their BMI is not very well correlated with their body fat percentage.
- eredengrin 7y ago
  Also this line > We conclude that despite wide variations in BMI and percent body fat among ultramarathon participants, the faster men have lower percent body fat values than the slower men, and finishers have lower percent body fat values than non-finishers. So I do stand corrected that not all of them are significantly below 10% body fat, but some definitely were (I don't see a breakdown anywhere giving an indication of how many), including some of the top finishers. I'd also imagine the ones at higher percentages who performed well probably have higher floors to begin with for how little body fat they can reasonably reach. In any case, it is not at all abnormal for BMI to have nothing to do with body fat percentage or how jacked someone looks, especially with athletes. BMI is probably one of the most meaningless health metrics in common use.
- dmix 7y ago
  Even further I'd imagine looking at the data for the top 30% of runners who are in the competitive tier this article is talking about would have more relevant and uniform data with narrower ranges.
runamok 7y ago
I've gone to ultras. You really need to have a range for the elites vs. everyone else. It's a very inclusive sport and you have participants that are fairly overweight even. Based on what I recall from my college track days where I knew my teammates' body fat percentages (4% to about 10%) I'd estinate that most elite men are at the lower end of that. Also because most men have more muscle mass their metabolic resting rate is higher so that definitely could be part of the reason why women and men peak performance is so close in ultras. They are using 10 to 15% more calories per hour I'd estimate. Also on a hilly course they need to tote that extra mass up a lot of extra climbs. I am surprised no one has mentioned Ann Trason that won 13 (iirc) Western States and used to win many ultras outright.
- atomical 7y ago
  Elite athletes that can't manage their weight so that they have enough body fat to last until the end of the race? I think not. Also, extremely low body fat can cause a host of other issues like low testosterone that could effect race performance. It's a small sport with not much competition.
Shorel 7y ago
BMI is basically useless for people who exercise regularly.