T Nation

Calipers vs. Dunk Tank

Today I had the privelage of finally using a dunk tank in ASU’s lab. I thought I would post my results.

At 207.25lbs I came in at 13.6% bodyfat. I had been guessing I was at 14% so I was pretty close. There are a few factors that could be influencing this though:

  1. Lots to drink last night (But I drank a ton of water both last night and today so I should have been properly rehydrated)

  2. Creatine supplementation?

  3. I’m taking 1-ad which generally makes me hold onto to an additional 10lbs I don’t know where.
    But overall the results seems to coinside with how I look.

Also this was done by my T.A. (doctoral student) so I think we can assume she knows what she is doing.

As a comparision I used calipers on myself afterwards (using three-site JP) and plugging my measurements into a population specific ACSM equation); I came out at right about 5% bodyfat. I asked my TA (who has a lot more practice than I do; since I’ve only used Accutrac calipers on myself) and her reading actually came in lower than mine on a few sites (We both measured 7mm on my chest; I measured 14 on my abdomen; she measured 10; and I measured 10 on my thigh and she measured 8). I didn’t plug it into the equations this time.

Also; looking online I plugged the numbers into a JP calculator;
for my readings I"m at 8.4 and for hers I’m a 6.5%. Wierd huh?

Do some reasearch on Body Fat measurments and the history of how it was developed, etc… To make a long story short, it is only good for measuring progress, doesn’t tell you exact body fat %, and can’t be compared across techniques. In otherwords, aesthetically you are better off looking at the mirror, body fat % is best left for analyzing accumulation/loss of LBM.

It’s as simple as seeing that according to both measurements, you lost and gained fat in a matter of hours. Go figure.

As far as calipers, people are too scared to pinch; they never grab anything worthwhile. I’d be willing to bet she didn’t grab as much as she could’ve.

Either way, nice work. Hydrostatic weighing, despite it being “gold standard” is estimated to be 3-4% off actual body fat.

I have been told they now use DEXA scans for fat measurment. anyone else heard that.

Yeah; they do. We had a discussion about those after class.

I am having the DEXA done on Thursday. I will give an update on what happens. I recently did skinfold and was at around 12%. I posted some pics around here a couple of months ago if you want see what I look like.


[quote]miniross wrote:
I have been told they now use DEXA scans for fat measurment. anyone else heard that. [/quote]

DEXA has been used for this purpose for over 10 years now.


It is just now being considered the “new gold standard”


post what the difference is. would be good to get an idea.

Also might want to check with Eric Cressey since he is at UConn and they have a DEXA machine there that they use.


  • Return with honor.


Your values wouldn’t be as skewed in the tank due to water, as much as they would be with air left in your lungs or throughout your intestines. Some people have anxiety about blowing out all their air and will therefore keep a little extra in their lungs. Other people have a larger residual volume than the equation figures. This will cause them to have an artificially higher BF%.

Since we all know that you are full of hot air, that may account for the difference between your skin-folds and the tank :slight_smile:

By the way, what was Foopa’s BF%. Sorry, I couldn’t resist.

Using calipers, I always liked using the 7 site formula. If you know how to use Excel, you can put the equation into it and then just make columns for the measurements and enter them and the program automatically calculates BF for you.

Take care,


Let me throw this one out. Proteinpowda said “she” checked his measurements and came in “lower”.
How about this theory, a female doing measurements on a male will be “more gentle or cautious” in pinching the skin. And would a male also be more gentle or careful in testing a member of the opposite sex. Give it a try. Get a male student to test you. See if the come in higher or lower.