1. THE ACCURACY OF BIOELECTRICAL IMPEDANCE ANALYSIS FOR ESTIMATING BODY COMPOSITION IN INDIVIDUALS WITH DEVELOPMENTAL DISABILITIES Brett S. Nickerson, ED.S; Angela R. Russell, M.Ed; Christopher T. Jenkins, B.S; Emily V. Witte, B.S.; Ronald L. Snarr Jr., B.S.; A.J. Mahurin, D.O.; and Michael R. Esco, Ph.D. Human Performance Lab, Auburn University Montgomery, Montgomery, AL Individuals with Developmental Disabilities (DD) are at a greater risk of obesity and chronic related diseases. Thus, predicting body fat percentage (BF%) in this population is important. However, accurate field methods such as bioelectrical impedance analysis (BIA) have not been thoroughly examined in individuals with DD. Most field measures of BF% have been validated using the general population. PURPOSE: The purpose of this investigation was to cross-validate the hand-to-foot BIA (HF-BIA) for predicting BF% in individuals with DD. METHODS: Seventeen individuals (15 men and 2 women) with DD (age = 32.3 ± 13.7 years) volunteered to participate in this study. Criterion BF% was determined via dual-energy x-ray absorptiometry (DXA). In addition, BF% was estimated by HF-BIA while the subjects assumed a supine position. RESULTS: The mean (+/- SD) determined by DXA was 37.6 ± 14.3% and by HF-BIA was 27.0 ± 11.4%. These values were significantly different (p < 0.05). A regression analysis revealed that HF-BIA significantly correlated with DXA (r = 0.77, R 2 = 0.60, p < 0.05) with a standard error of estimate ± 9.31%. The constant error (CE) for HF-BIA was -10.5% and revealed limits of agreement of 28.4% below to 7.4% above the DXA. CONCLUSIONS: This study found that HF- BIA significantly underestimated BF% and provided a large SEE in individuals with DD. Therefore, practitioners should use extreme caution when predicting BF% with HF-BIA in this population. Future research is warranted to develop appropriate field predictors of BF% in individuals with DD. Procedures Height was measured with a SECA stadiometer and rounded to the nearest 0.05 cm. Weight was measured with a TANITA (BWB-800A) digital scale and rounded to the nearest 0.05 kg. For HF-BIA, subjects were asked to take off their shoes and socks, lie in supine position, and to place arms by their sides. A whole-body DXA scan (GE Lunar Prodigy, Software version 10.50.086, GE Lunar Corporation, Madison, WI, USA) was used as the criterion method of BF%. DXA was calibrated before each scan on a subject. Prior to each DXA scan, subjects looked over pictures of what a scan would be like to serve as a visual for understanding. If subjects were comfortable with proceeding, they were asked to remove all metals such as jewelry, etc. and shoes. Subjects were then asked to lie motionless in supine position with their arms by their sides. To limit motion, subjects ankles were held together with a Velcro strap. Conclusions Introduction Methods Individuals with Developmental Disabilities (DD) are at a greater risk of obesity and related chronic related diseases. Accurately measuring BF% is important for knowing whether a person is at risk for cardiovascular diseases (2). Predicting body fat percentage (BF%) in special populations is important when establishing life style interventions designed to promote healthy body weight. Hand-to-foot bioelectrical impedance analysis (HF-BIA) is a simple and inexpensive method for predicting BF% in field and clinical settings. Various studies have measured the accuracy of HF-BIA in the general population. However, there is very little research to date cross-validating HF-BIA in individuals with DD (3). Participants Seventeen individuals with DD (n=17) volunteered to participate in this study. Subjects were measured for height, weight, HF-BIA, and DXA. Abstract Purpose The purpose of this investigation was to cross-validate HF-BIA for measuring BF% in individuals with DD by using dual energy x-ray absorptiometry (DXA) as the criterion. The mean (+/- SD) determined by DXA was 37.6 ± 14.3% and by HF-BIA was 27.0 ± 11.4%. These values were significantly different (p < 0.05). A regression analysis revealed that HF-BIA significantly correlated with DXA (r = 0.77, R 2 = 0.60, p < 0.05) with a standard error of estimate ± 9.31%. The constant error (CE) for HF-BIA was -10.5% and revealed limits of agreement of 28.4% below to 7.4% above the DXA. References This study found that HF-BIA significantly underestimated BF% and provided a large SEE in individuals with DD. Therefore, practitioners should use extreme caution when predicting BF% with HF-BIA in this population. Future research is warranted to develop appropriate field predictors of BF% in individuals with DD. Practical Applications Exercise Scientists, Personal Trainers, and Strength and Conditioning Specialist who work with individuals with DD in a health and fitness setting should be aware of the HF-BIA. Because of the HF-BIA ease of use, low cost, and quick administration, it has potential to become widely used for people with special needs. However, practitioners should consider the results of this investigation before using this method for measuring BF% as it appears to have a large SEE, in addition to under predicting BF&.. 1. Gonzalez-Aguero, A., Ara, I., Moreno, L.A., Vicente- Rodriguez, G., & Casajus, J.A. (2011). Fat and lean masses in youths with Down syndrome: gender differences. Research in Developmental Disabilities, 32, 1685-1693. 2. Koutoubi, S., & Huffman, F.G. (2005). Body Composition Assessment and Coronary Heart Disease Risk Factors among College Students of Three Ethnic Groups. Journal of the National Medical Association, 97(6), 784-91. 3. Loveday, S.J., Thompson, J.M., & Mitchell, E.A. (2012). Bioelectrical Impedance for measuring body fat in young persons with Down syndrome: validation with dual-energy absorptiometry. Acta Paediatr, 101(11), 491-495. Results HUMAN PERFORMANCE LABORATORY Figure 1: Mean BF% comparison between the DXA and HF-BIA (n = 17). *HF-BIIA was significantly lower than DXA (p < 0.05) * Figure 2: Bland-Altman Plot representing the relationship between the differences between the two measures and the mean. The middle solid line represents the constant error (CE). The two outside dashed lines represent 1.96 SD of the CE. Table 1. Descriptive Characteristics (n=17) Variable Mean ± SD Age yrs 21.10 ± 1.95 Height cm 164.16 ± 7.84 Weight kg 69.50 ± 14.88 Table 2. Developmental Disabilities (n=17) DisabilityParticipants Down Syndrome 4 Cerebral Palsy 3 Traumatic Brain Injury 3 Spinal Cord Injury 3 Intellectual Disability 2 Multiple Sclerosis 1 Stroke 1 DXA + HF-BIA / 2 DXA – H F-BIA