Predictive model specific to young adults for estimating thoracic gas volume for air‐displacement plethysmography

The BOD POD, a new air-displacement plethysmograph for measuring human body composition, utilizes the inverse relationship between pressure and volume (Boyle’s law) to measure body volume directly. The quantity of air in the lungs during tidal breathing, the average thoracic gas volume (Vtg), is also measured by the BOD POD by using a standard plethysmographic technique. Alternatively, the BOD POD provides the use of a predicted Vtg (Vtgpred). The validity of using Vtgpred in place of measured Vtg (Vtgmeas) to determine the percentage of body fat (%BF) was evaluated in 50 subjects (36 women, 14 men; ages 18–56 yr). There was no significant difference between Vtgmeas and Vtgpred (mean difference ± SE, 53.5 ± 63.3 ml) nor in %BF by using Vtgmeas vs. Vtgpred (0.2 ± 0.2 %BF). On an individual basis, %BF measured by using Vtgmeas vs. Vtgpred differed within ±2.0% BF for 82% of the subjects; maximum differences were −2.9 to +3.0% BF. For comparison, data from 24 subjects who had undergone hydrostatic weighing were evaluated for the validity of using predicted vs. measured residual lung volume (Vr pred vs. Vr meas, respectively). Differences between Vr meas and Vr pred and in %BF calculated by using Vr meas vs. Vr pred were significant (187 ± 46 ml and 1.4 ± 0.3% BF, respectively; P < 0.001). On an individual basis, %BF determined by using Vr meas vs. Vr preddiffered within ±2.0% BF for 46% of the subjects; maximum differences were −2.9 to +3.8% BF. With respect to %BF measured by air displacement, our findings support the use of Vtgpred for group mean comparisons and for purposes such as screening in young to middle-aged individuals. This contrasts with the use of Vr pred in hydrostatic weighing, which leads to significant errors in the estimation of %BF. Furthermore, although the use of Vtgpred has some application, determining Vtgmeas is relatively simple in most cases. Therefore, we recommend that the use of Vtgmeas remain as standard experimental and clinical practice.

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Validity of new child-specific thoracic gas volume prediction equations for air-displacement plethysmography

BMC Pediatrics ◽

10.1186/1471-2431-6-18 ◽

2006 ◽

Vol 6 (1) ◽

Cited By ~ 3

Author(s):

Paul B Higgins ◽

Analiza M Silva ◽

Luis B Sardinha ◽

Holly R Hull ◽

Michael I Goran ◽

...

Keyword(s):

Prediction Equations ◽

Air Displacement Plethysmography ◽

Thoracic Gas Volume ◽

Gas Volume

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Assessment and prediction of thoracic gas volume in pregnant women: an evaluation in relation to body composition assessment using air displacement plethysmography

British Journal Of Nutrition ◽

10.1017/s0007114512000906 ◽

2012 ◽

Vol 109 (1) ◽

pp. 111-117 ◽

Cited By ~ 12

Author(s):

Pontus Henriksson ◽

Marie Löf ◽

Elisabet Forsum

Keyword(s):

Body Composition ◽

Body Weight ◽

Pregnant Women ◽

Maternal Nutrition ◽

Body Volume ◽

Body Composition Assessment ◽

Air Displacement Plethysmography ◽

Bod Pod ◽

Thoracic Gas Volume ◽

Gas Volume

Assessment of body fat (BF) in pregnant women is important when investigating the relationship between maternal nutrition and offspring health. Convenient and accurate body composition methods applicable during pregnancy are therefore needed. Air displacement plethysmography, as applied in Bod Pod, represents such a method since it can assess body volume (BV) which, in combination with body weight, can be used to calculate body density and body composition. However, BV must be corrected for the thoracic gas volume (TGV) of the subject. In non-pregnant women, TGV may be predicted using equations, based on height and age. It is unknown, however, whether these equations are valid during pregnancy. Thus, we measured the TGV of women in gestational week 32 (n 27) by means of plethysmography and predicted their TGV using equations established for non-pregnant women. Body weight and BV of the women was measured using Bod Pod. Predicted TGV was significantly (P = 0·033) higher than measured TGV by 6 % on average. Calculations in hypothetical women showed that this overestimation tended to be more pronounced in women with small TGV than in women with large TGV. The overestimation of TGV resulted in a small but significant (P = 0·043) overestimation of BF, equivalent to only 0·5 % BF, on average. A Bland–Altman analysis showed that the limits of agreement were narrow (from − 1·9 to 2·9 % BF). Thus, although predicted TGV was biased and too high, the effect on BF was marginal and probably unimportant in many situations.

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Selection of a Thoracic Gas Volume When Using Air Displacement Plethysmography to Assess Longitudinal Body Composition Changes

International Journal of Sport Nutrition and Exercise Metabolism ◽

10.1123/ijsnem.2017-0085 ◽

2017 ◽

Vol 27 (6) ◽

pp. 485-486

Author(s):

Patrick B. Wilson

Keyword(s):

Body Composition ◽

Air Displacement Plethysmography ◽

Thoracic Gas Volume ◽

Gas Volume ◽

Composition Changes ◽

Selection Of

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Body-Density Measurement in Children: The BOD POD Versus Hydrodensitometry

International Journal of Sport Nutrition and Exercise Metabolism ◽

10.1123/ijsnem.21.3.240 ◽

2011 ◽

Vol 21 (3) ◽

pp. 240-247 ◽

Cited By ~ 4

Author(s):

Jason C. Holmes ◽

Ann L. Gibson ◽

J. Gualberto Cremades ◽

Constance M. Mier

Keyword(s):

Cross Validation ◽

Density Measurement ◽

Regression Analyses ◽

Body Density ◽

Air Displacement Plethysmography ◽

Bod Pod ◽

Thoracic Gas Volume ◽

Significant Difference ◽

Mean Differences ◽

Gas Volume

Objective:To compare estimates of body density (Db) from air-displacement plethysmography (ADP) with measured and predicted thoracic-gas-volume (TGV) measurements and those from hydrodensitometry (HD) in children.Methods:Seventeen participants (13 male and 4 female; 10.1 ± 2.20 yr, 42.0 ± 15.03 kg, 145.6 ± 17.41 cm, 30.0 ± 8.66 kg/m2) were tested using ADP and HD, with ADP always preceding HD. Db estimates were compared between ADP with measured TGV, ADP with predicted TGV, and the reference measure, HD. Regression analyses were used to assess the accuracy of the ADP methods, and potential bias between the ADP procedures and HD were evaluated using Bland–Altman analyses. The cross-validation criteria described by Lohman for estimating Db relative to HD were used to interpret the results of the study.Results:A significant difference was found between Db estimates from ADP with measured TGV (1.0453 ± 0.01934 g/cm3) and ADP with predicted TGV (1.0415 ± 0.01858 g/cm3); however, neither was significantly different from Db obtained by the reference HD procedure (1.0417 ± 0.02391 g/cm3). For both ADP procedures, regression analyses produced an r = .737–.738, r2 = .543−.544, and SEE = 0.02 g/cm3, and the regression lines deviated significantly from the line of identity; however, no significant biases were indicated.Conclusions:Despite no significant mean differences between Db estimates from the ADP procedures and HD, more cross-validation research is needed before recommending the BOD POD for routine use with children in clinical and research settings.

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Effect of Predicted Versus Measured Thoracic Gas Volume on Body Fat Percentage in Young Adults

International Journal of Sport Nutrition and Exercise Metabolism ◽

10.1123/ijsnem.2020-0342 ◽

2021 ◽

pp. 1-5

Author(s):

Jeremy B. Ducharme ◽

Ann L. Gibson ◽

Christine M. Mermier

Keyword(s):

Young Adults ◽

Body Fat ◽

Body Fat Percentage ◽

Fat Percentage ◽

Men And Women ◽

Percentage Body Fat ◽

Thoracic Gas Volume ◽

The Difference ◽

Predictor Model ◽

Gas Volume

The BodPod® (COSMED, Concord, CA) uses predicted (pTGV) or measured thoracic gas volume (mTGV) during estimations of percentage body fat (%BF). In young adults, there is inconsistent evidence on the variation between pTGV and mTGV, and the effect of sex as a potential covariate on this relationship is unknown. This study examined the difference between TGV assessments and its effect on %BF and potential sex differences that may impact this relationship. A retrospective analysis of BodPod® pTGV and mTGV for 95 men and 86 women ages 18–30 years was performed. Predicted TGV was lower than mTGV for men (−0.49 ± 0.7 L; p < .0001). For men, %BF derived by pTGV was lower than that by mTGV (−1.3 ± 1.8%; p < .0001). For women, no differences were found between pTGV and mTGV (−0.08 ± 0.6 L; p > .05) or %BF (−0.03 ± 0.2%; p > .05). The two-predictor model of sex and height was able to account for 57.9% of the variance in mTGV, F(2, 178) = 122.5, p < .0001. Sex corrected for the effect of height was a significant predictor of mTGV (β = 0.483 L, p < .0001). There is bias for pTGV to underestimate mTGV in individuals with a large mTGV, which can lead to significant underestimations of %BF in young adults; this was especially evident for men in this study. Sex is an important covariate that should be considered when deciding to use pTGV. The results indicate that TGV should be measured whenever possible for both men and women ages 18–30 years.

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Changes in thoracic gas volume with air-displacement plethysmography after a weight loss program in overweight and obese women

European Journal of Clinical Nutrition ◽

10.1038/sj.ejcn.1602709 ◽

2007 ◽

Vol 62 (3) ◽

pp. 444-450 ◽

Cited By ~ 7

Author(s):

C S Minderico ◽

A M Silva ◽

D A Fields ◽

T L Branco ◽

S S Martins ◽

...

Keyword(s):

Weight Loss ◽

Weight Loss Program ◽

Obese Women ◽

Air Displacement Plethysmography ◽

Thoracic Gas Volume ◽

Gas Volume

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Body composition measurement by air displacement plethysmography in pregnancy: Comparison of predicted versus measured thoracic gas volume

Nutrition ◽

10.1016/j.nut.2018.09.035 ◽

2019 ◽

Vol 60 ◽

pp. 227-229 ◽

Cited By ~ 2

Author(s):

Outi Pellonperä ◽

Ella Koivuniemi ◽

Tero Vahlberg ◽

Kati Mokkala ◽

Kristiina Tertti ◽

...

Keyword(s):

Body Composition ◽

Air Displacement Plethysmography ◽

Body Composition Measurement ◽

Thoracic Gas Volume ◽

Composition Measurement ◽

Gas Volume ◽

In Pregnancy

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Effect of Thoracic Gas Volume Changes on Body Composition Assessed by Air Displacement Plethysmography after Rapid Weight Loss and Regain in Elite Collegiate Wrestlers

Sports ◽

10.3390/sports7020048 ◽

2019 ◽

Vol 7 (2) ◽

pp. 48 ◽

Cited By ~ 1

Author(s):

Emi Kondo ◽

Keisuke Shiose ◽

Yosuke Yamada ◽

Takuya Osawa ◽

Hiroyuki Sagayama ◽

...

Keyword(s):

Weight Loss ◽

Body Composition ◽

Fat Free Mass ◽

Dilution Method ◽

Rapid Weight Loss ◽

Body Composition Assessment ◽

Air Displacement Plethysmography ◽

Time Points ◽

Thoracic Gas Volume ◽

Gas Volume

We investigated the effect of rapid weight loss (RWL) and weight regain (WR) on thoracic gas volume (VTG) and body composition assessment using air displacement plethysmography (ADP) in male wrestlers. Eight male elite collegiate wrestlers completed a RWL regimen (6% of body mass) over a 53-h period, which was followed by a 13-h WR period. ADP was used at three time points (baseline (T1), post-RWL (T2) and post-WR (T3)) according to the manufacturer’s testing recommendations. The total body water and bone mineral content were estimated using the stable isotope dilution method and dual energy X-ray absorptiometry, respectively, at the same time points. Body composition was assessed with two-component (2C) or four-component (4C) models using either the measured VTG (mVTG) or predicted VTG (pVTG). Measured VTG increased from T1 to T2 (0.36 ± 0.31 L, p < 0.05) and decreased from T2 to T3 (−0.29 ± 0.15 L, p < 0.01). However, the changes in fat mass and fat free mass, which were calculated by both 2C and 4C models, were not significantly different when compared between calculations using mVTG and those using pVTG. Our results indicate that VTG significantly changes during RWL and WR, but both measured and predicted VTG can be used to assess changes in body composition during RWL and WR.

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