1. Introduction & Purpose Practical Applications
COMPARISON OF 3-COMPARTMENT MODEL BODY FAT PREDICTIONS VIA BIOIMPEDANCE DEVICES AND THE INFLUENCE OF HYDRATION IN FEMALE ATHLETES
Ronald L. Snarr1, Michael R. Esco1, Jordan Moon2, Chih-Yin Tai3, Kristy Crowley4, and Brandon Spadley3
1Department of Kinesiology, The University of Alabama, Tuscaloosa, AL; 2Impedimed, Inc., Carlsbad, CA;
3United States Sports Academy, Daphne, AL; 4CPH Business Academy, Copenhagen, Denmark
Abstract
Introduction & Purpose
Results
Proper hydration status is not only important in sport performance, but can be helpful when attempting to estimate body fat percentage in athletes. Such methods of monitoring hydration status include deuterium oxide dilution (D2O), which may not be readily available and can be costly and time consuming. Therefore, alternative means of estimating total body water (TBW) have been suggested, such as single and multi-frequency bioelectrical impedance devices. However, the accuracy of these methods has yet to be validated in female athletes. PURPOSE: The purpose of this investigation was two-fold: 1) examination of the agreement between 3-C model estimates of BF%, which utilized D2O as a criterion, and six bioelectrical impedance devices and methods, using an estimation of TBW; and 2) determine the validity of BF% estimations when accounting for different levels of fat-free mass hydration status. METHODS: Fifty-two females (age = 24 ± 8.9 years, height = ± 5.7 cm, weight = 62.5 ± 8.3 kg) volunteered to participate in this investigation. Participants completed multiple laboratory measures to determine body fat percentage via 3-C model calculations. D2O was used as the criterion measure for TBW, while hydrostatic weighing served as the criterion for body volume. Additionally, TBW was estimated via the use of three laboratory bioimpedance devices (bioimpedance spectroscopy [BIS], multi-frequency bioimpedance [MFBIA], and single-frequency bioimpedance [SFBIA]) and three home-use bioimpedance scales (HS1, HS2, HS3). Furthermore, the accuracy of the six bioimpedance devices were compared within the entire sample (n = 52), as well as in a sub-sample of subjects (n = 28) who were characterized as having a FFM hydration value that was either > 74.8% or < 72.2%. RESULTS: Results of this investigation demonstrated a sample (n = 52) mean (±SD) BF% of ± 5.39% for the 3-C (criterion) model, ± 4.91% for BIS, ± 5.79% for MFBIA, ± 4.77% for SFBIA, ± 4.47% for HS1, ± 4.57% for HS2, and ± 6.28% for HS3. The bias and limits of agreement (bias ± 1.96*SD) for each of the predictive measures in the sample (n =52) were as follows: BIS 0.19 ± 4.78, MFBIA 0.36 ± 4.71, SFBIA ± 4.84, HS ± 4.81, HS ± 5.18, HS ± After accounting for improper hydration status, the sub-sample (n = 28) had a mean BF% of ± 5.09% for the 3-C model (criterion), ± 5.17% for BIS, ± 6.16% for MFBIA, ± 5.18% for SFBIA, ± 4.48% for HS1, ± 4.96% for HS2, and ± 6.72% for HS3. The limits of agreement (bias ± 1.96*SD) for each of the predictive measures in the sub-sample (n =28) were 0.25 ± 4.71 for BIS, 0.75 ± 5.46 for MFBIA, ± 4.98 for SFBIA, 0.59 ± 5.13 for HS1, ± 5.18 for HS2, and 0.38 ± 7.13 for HS3. CONCLUSION: Results of this investigation demonstrate that BIS and HS2 provided the smallest mean differences and limits of agreement for the entire sample; while BIS and HS1 provided the smallest differences and limits for the sub-sample with abnormal FFM hydration. Additionally, SFBIA significantly overestimated BF% as compared to the criterion 3-C model. PRACTICAL APPLICATION: Practitioners should take note that abnormal hydration (i.e., >74.8% or < 72.2%) status may alter 3C BF% results when using TBW from certain bioimpedance methods in female athletes. The BIS-based 3C model produced the best individual agreement and was not affected by abnormal hydration and therefore is suggest for use when measuring TBW in 3C model in female athletes.
Alternative means of estimating total body water (TBW) have been suggested, such as single and multi-frequency bioelectrical impedance devices. However, the accuracy of these methods has yet to be validated in female athletes.
Purpose of this investigation was two-fold: 1) examination of the agreement between 3-C model estimates of BF%, which utilized D2O as a criterion, and six bioelectrical impedance devices and methods, using an estimation of TBW; and 2) determine the validity of BF% estimations when accounting for different levels of fat-free mass hydration status.
Normal Hydration
Abnormal Hydration
95% Limits of Agreement
Methods
Fifty-two females (age = 24 ± 8.9 years, height = ± 5.7 cm, weight = 62.5 ± 8.3 kg) volunteered to participate in this investigation.
Participants completed multiple laboratory measures to determine body fat percentage via 3-C model calculations using D2O as the criterion measure for TBW and hydrostatic weighing served as the criterion for body volume
TBW was estimated via the use of three laboratory bioimpedance devices (bioimpedance spectroscopy [BIS] (SFB7, Impedimed, Inc.), multi-frequency bioimpedance [MFBIA] (InBody 720), and single-frequency bioimpedance [SFBIA] (DF50, Impedimed, Inc.) and three home-use bioimpedance scales ([HS1] (Taylor 5568), [HS2] (Tanita BF-680W), [HS3] (Health-o-Meter BFM081DQ1-63)).
The accuracy of the six bioimpedance devices were compared within the entire sample (n = 52), as well as in a sub-sample of subjects (n = 28) who were characterized as having a FFM hydration value that was either > 74.8% or < 72.2%.
BIS MFBIA SFBIA HS HS HS3
Body Composition Measure
Figure 1. 95% Limits of Agreement for each bioimpedance devices compared to 3-C criterion
Conclusions
Results of this investigation demonstrate that proper hydration plays a key role in the estimation of TBW and accuracy of using the 3-C model in female athletes.
The devices BIS and HS2 provided the smallest mean differences and limits of agreement for the entire sample; while BIS and HS1 provided the smallest differences and limits for the sub-sample with abnormal FFM hydration.
Additionally, SFBIA significantly overestimated BF% as compared to the criterion 3-C model.
Results
Practical Applications
Table 1. Validation of all methods for predicting BF% in women compared to 3CCRITERION (n = 52)
Practitioners should take note that abnormal hydration (i.e., >74.8% or < 72.2%) status may alter 3C BF% results when using estimated TBW from certain bioimpedance methods in female athletes.
The BIS-based 3C model produced the best individual agreement and was not affected by abnormal hydration and therefore is suggest for use when measuring TBW in 3C model in female athletes.
Value
Mean ± SD P r TE
SEE CE
Limits
3CCRITERION
23.5 ± 5.4 -
BIS
23.3 ± 4.9
0.58
0.89
2.42
2.46
0.19
±4.8
MFBIA
23.2 ± 5.8
0.29
0.91
2.41
2.26
0.36
±4.7
SFBIA
27.1 ± 4.8
0.001
4.33
2.50
-3.57
HS1
23.4 ± 4.5
0.79
2.43
-0.62
HS2
16.7 ± 7.9
0.1
0.87
2.69
2.67
±5.2
HS3
23.7 ± 6.3
0.66
0.86
3.15
2.76
-0.19
±6.2
ACKNOWLEDGMENTS
This study was funded by Impedimed, Inc.