My wife and I are having an argument about percentage of body fat on highly trained runners. I'm saying it is possible to have as low as 3%, she's saying just shy of 10%. What are the facts?
My wife and I are having an argument about percentage of body fat on highly trained runners. I'm saying it is possible to have as low as 3%, she's saying just shy of 10%. What are the facts?
You're correct for men, she's correct for women.
Numbers vary considerably according to the method of testing. Skinfold measurements are probably the most reliable.
Elite men at their peak of race fitness tend to be around 6% and Women 10%
When you read about someone with 3% they are probably in the 6% range by the Skinfold test.
Funny you mention this. I just had my body fat composition taken via the skin fold test and I was at 3 percent. I\'m not \"highly trained\", just run a lot and really skinny :)
3-8 percent
wellnow wrote:
Skinfold measurements are probably the most reliable.
Wrong, the under water test is the actual test that is 100% accurate. Skin fold is the next best thing, though. I don't trust anything else. The scales that have a body fat measurement varies for about 3%.
DEXA (Dual Energy X-ray Absorptiometry) is actually more accurate.
I've read 5% (men) to 10% (women).
Anyone who actually thinks they're 3% is probably wrong. That's about the lowest amount of fat your body needs just to function, let alone run all the time. Even the really lean elite runners are probably closer to 5%, with most well-trained male runners at 7-12 percent. I could be wrong though because I'm not an exercise physio or anything like that.
Underwater weighing isn't 100% accurate. Even it has a +/- error of about 2%. Mostly due to not expiring all of your air before being "weighed". DEXA has a +/1 error of about 1%.
As always with most means of body fat measurement, if you're extremely lean or extremely obese there is a higher rate of error.
The lowest you can possibly go is likely very dependant on genetic factors. Bodybuilders during competiton have the lowest body fat of any athlete at around 3-5%...and this is because they nearly starve themselves and drain their body of any available water for two weeks leading up to competiton..ie: it is not healthy. Anything under 10% is considered very lean and any endurance athlete should have no problem getting to around 5-10%.
Let's look at an athlete with 130lbs of fat free mass. At 5% body fat he weighs about 136lbs, at 10% body fat he weights about 145lbs.
Alan
Runningart2004, I think your math might be backwards. Percentage body fat is relative to current weight.
To figure out what a 130 lbs fat free body would weight with 5 & 10% body fat, you'd use:
CW = 100*LW/(100 - PBF)
LW = CW*(100 - PBF)/100
CW == current weight (with fat)
LW == lean weight
PBF is the Percentage of body fat.
So 130 lbs fat free body with 5% BF gives 136.8 and with 10% gives 144.4 Rounding off means 137 lbs and 144 lbs.
Yeah its nick picking, but with larger numbers is makes a big difference.
They have a pretty accurate means of measuring the air left in your lungs. The lab I worked had an apparatus from which you exhale as much air as you can and then inhale a known volume of nitrogen. After several breaths in and out of the apparatus, the mixture reaches and equilibrium from which you can calculate the residual volume of the lungs.
My favorite part of the calculation was the standard estimate of the volume of "air" in the intestinal tract. (I know that was a big variable for me.)
At the time I was 5'9 1/2" and 132 lbs. Underwater weighing had me at 7% fat. I didn't function well any lighter than that.
So I think for athletes, measuring your body fat % might give you a nice number to brag about, but finding your ideal weight is mostly by trial and error.