Bod pod or hydrostatic

[shan]

I found a research study designed to see how hydration affected different methods of body composition analysis, it compared hydrostatic weighing (HW in the results), air displacement via bodpod (ADP) and skinfold (SK)
here is a portion of the results, I will include a link to the paper at the bottom.

hydration status (N  66).
Hydrated Dehydrated
Weight (kg) 76.7
13.1 74.7
12.9*
%BF HW 11.3
4.8 11.1
4.7
%BFADP 11.0
5.3 10.1
5.1*
%BFSK 12.4
4.8† 12.2
4.5‡
FFMHW (kg) 67.7
10.1 66.1
10.0*
FFMADP (kg) 67.9
9.7 66.8
9.7*
FFMSK (kg) 66.9
10.5 65.4
10.3*
Values are expressed as mean
SD.
* Significantly different from the hydrated state (P  0.001) (multiple pairedsample
t-tests with Bonferroni’s adjustment).
† Significantly different from the corresponding body composition variables by
HW within the hydrated state and dehydrated state (‡) (P  0.05) (repeatedmeasures
one-way ANOVA, with Dunnett multiple comparison procedure).
‡ Significantly different from the corresponding body composition variables by
HW within the dehydrated state (P  0.05) (repeated-measures one-way ANOVA,
with Dunnett multiple comparison procedure).
Db, body density; %BF, percent body fat; FFM, fat-free mass; HW, hydrostatic
weighing; ADP, air displacement plethysmography; SK, skinfolds.
TABLE 1. Subject characteristics (N  66).
Age (yr) 20.2
2.0
Height (m) 1.73
0.08
Weight (kg) 77.1
13.2
Wrestling experience (yr) 9.0
1.1
Values are expressed as mean
SD.
502 Official

http://wweb.uta.edu/faculty/ricard/...ed Measures ANOVA/Repeated Measures ANOVA.pdf

 

[shan]

notice that while all testing methods were impacted by hydration (or more accurately, lack thereof) the hydrostatic weighing and skinfold were only off by 0.2 percent while the air displacement was off by almost a full percentage (0.9)
%BF HW 11.3 hydrated 11.1 dehydrated
%BFADP 11.0 hydrated 10.1 dehydrated
%BFSK 12.4 hydrated 12.2 dehydrated

with this in mind, it would seem logical that overhydration would increase bf% by a similar amount (but I have not seen a study to confirm that).

 

[Rottenrogue]

lol shan my head just exploded reading that.But I got the jist of it .Thankyou

 

[shan]

LOL! Sorry if TMI...the scientist in me feels obligated to provide research LOL. Density fluctuates with changes in hydration..thats it in a nutshell LOL.

 

[SugarFree]

Gotta thow some contradictions at ya

Evaluation of Air Displacement for Assessing Body Composition of Collegiate Wrestlers

Conclusions: This study demonstrates that the BOD POD air displacement method provides similar estimates of Db, %BF, and FFM when compared with HW in a heterogeneous collegiate wrestling population during hydrated and acutely
dehydrated states

 

[dangerouscurves]

Ok one more question can any of them differentiate skin from fat ??

 

[r4mpage]

What do the prices generally range for the services of either of the dexa, bodpod or the others? I mean, Arnold, Dorian, Lou and Franco just used mirrors, I might stay old school with them unless these tests are cheap lol.

 

[shan]

I think that the scientific conclusion that it is not statistically significant difference is because it is less than 5% which is the usually accepted standard deviation (I did not have time to read the whole thing at the moment). But...in my opinion the fact that it was a 0.2% difference for SF and HW as opposed to 0.9% difference for bodpod shows there is more room for error with ADP in a dehydrated state(which has nothing to do with scientific evaluations, more from a bb'r point of view).

They cannot determine skin from fat and having excess skin could probably skew results in the bodpod (if it is enough skin to move around during the test it could for sure affect results)..since even body hair can cause fluctuations LOL.

Cost for bodpod here is 25 bucks, the hydrostatic weighing was 55 for the first time and 35 thereafter, so not a huge amount on either one (not something you need to do every month).

 

[r4mpage]

I think that the scientific conclusion that it is not statistically significant difference is because it is less than 5% which is the usually accepted standard deviation (I did not have time to read the whole thing at the moment). But...in my opinion the fact that it was a 0.2% difference for SF and HW as opposed to 0.9% difference for bodpod shows there is more room for error with ADP in a dehydrated state(which has nothing to do with scientific evaluations, more from a bb'r point of view).

They cannot determine skin from fat and having excess skin could probably skew results in the bodpod (if it is enough skin to move around during the test it could for sure affect results)..since even body hair can cause fluctuations LOL.

Cost for bodpod here is 25 bucks, the hydrostatic weighing was 55 for the first time and 35 thereafter, so not a huge amount on either one (not something you need to do every month).

Oh, that's nothing. I heard people throwing numbers out there in the couple hundreds, I was like wtf.

 

[SugarFree]

What do the prices generally range for the services of either of the dexa, bodpod or the others? I mean, Arnold, Dorian, Lou and Franco just used mirrors, I might stay old school with them unless these tests are cheap lol.

This can vary greatly depending on the location. The bodpod I goto is $50 but more often then not I usually see others quoting $25 where they go for it. I like the place I goto so the fee isnt a problem.

For the Dexa, I've read anywhere from 100 to $250 per test. The place I went to the other week though was only $50. Im still kinda surprised by this specially since there were 2-3 staff helping us the whole time. I think there way undercharging there but not gonna complain.

Many of these places seem to have deals for customers going on a semi regular basis.

 

[SugarFree]

Cmon now Shan, lets not get carried away. The BodPod isnt a wind tunnel and its not like a persons skin is flopping around in the little bit of air it disperses. Although I did laugh thinking about it.

Shan, what type of place does the HW testing? Is it a fitness type company or a college/hospital type thing. No clue where to look around here although as said, I'm interested in trying all methods.

I never did think to ask this question of the doc though about skin being counted as fat - just assumed it would be counted towards LBM. However I did ask (for the wife of course) how much breast implants would effect the test or not (I bet that would mess up the HW tests)... DC if ya want a more detailed answer for the bodpod, I can email the doc and ask her. She's great about answering this stuff.

I think if your that worried about the detail of the results though, you would be better suited for looking into the dexa scan which is a 3 compartment scan opposed to bodpod or hydrodrastic which is 2 compartment. The two compartment test divides the answers into fat mass and fat free mass. The 3 compartment scan divides the results into fat mass, bone mass, and lean mass.

I dont know if that winds up being more benifical to judging progress or not but the reults they gave were really in depth and although Im not sure why they seemed in more detail for females then males. The wife was given many more print outs then I. Even got xray type pictures showing where you hold the fat in your body.

 

[shan]

have you been in a bodpod LOL...the air pressure changes can feel pretty "whooshy"....and I have seen peoples skin flapping in the breeze outdoors...why not in the pod LOL. Just saying, if body hair can impact it I am sure skin folds can too (whether or not they flap in the breeze) if air could get into the folds it could affect it-just sayin

being a biologist actually makes me think of lots of intricate variables that "could" theoretically affect readings LOL...I would want to do a study to test some of these...." hair or not, a case study for air displacement", "3 skin flaps in the wind, yet another case study on air displacement"...."dehydrated AND smooth vs. overhydrated and smooth" with it's sister studies "overhydrated and smooth vs. overhydrated and hairy" and "dehydrated and smooth vs. dehydrated and hairy"
yes, I am ready for the weekend