RELIABILITY OF BODY COMPOSITION MEASURED USING A SMARTPHONE APPLICATION AND DIFFERENT CAMERA RESOLUTIONS

Mary E. Lovelady, Casey J. Metoyer, Katherine Sullivan, Jacob Broeckel, Michael R. Esco, FACSM, Michael V. Fedewa. University Of Alabama, Tuscaloosa, AL. BACKGROUND: Many traditional laboratory methods of measuring body fat percentage (%Fat) are inaccessible to healthcare professionals due to the cost, complexity, time, and portability. Recently, a new smartphone application was developed that allows for an accurate estimate of %Fat by analyzing a single 2-dimensional digital image. Although the validity of the application has been previously examined, the reliability across different camera resolutions has not been thoroughly tested. PURPOSE: The aim of this study was to evaluate the reliability of %Fat estimates from digital images captured using devices with different megapixel cameras. METHODS: A convenience sample of adult participants was recruited for the study (n=12, 83.33% female, 83.33% Caucasian, 31.25±10.49 yrs., 69.44±11.77 kg/m2). Age, gender, and race/ethnicity were assessed via self-report. Height was measured to the nearest 0.1 cm using a stadiometer (SECA 213, Seca Ltd., Hamburg, Germany). Weight was measured to the nearest 0.1 kg using a calibrated digital scale (Tanita BWB-800, Tanita Corporation, Tokyo, Japan). A full-body digital image was taken from the posterior view, with participants standing in front of a white background, using a 12-megapixel iPhone 12 (Apple Inc., Cupertino, CA) (%Fat12mp) and an 8-megapixel iPad Air 2 (Apple Inc., Cupertino, CA) (%Fat8mp). %Fat was derived using an automated smartphone application and a proprietary algorithm (made Health and Fitness, LLC, Birmingham, AL). A paired samples t-test was used to examine potential mean differences between %Fat12mp and %Fat8mp. The reliability was also measured using Pearson’s r, and described as weak, moderate, strong, or near-perfect (r=0.2, 0.5, 0.8, or 0.9 respectively). Data are presented as mean±standard deviation, with an alpha level set to p\u3c0.05. RESULTS: No significant mean differences in %Fat were observed between %Fat12mp and %Fat8mp (26.92±4.96 %Fat and 27.16±3.08 %Fat, respectively; p=0.37). Near-perfect correlations were observed between %Fat12mp and %Fat8mp (r=0.99, p\u3c0.001). DISCUSSION: Based on the results of this study, the smartphone application provides a reliable estimate of %Fat across devices with different megapixel cameras. Future studies should explore other conditions, including different lighting, different color backgrounds, and other devices, as well as within a larger more diverse sample

THE TEST-RETEST RELIABILITY OF BODY COMPOSITION MEASURED USING DIGITAL IMAGES FROM A SMARTPHONE APPLICATION

Madeline L. Schwing, Casey J. Metoyer, Katherine Sullivan, Mary E. Lovelady, Michael R. Esco, FACSM, Michael V. Fedewa, FACSM. University of Alabama, Tuscaloosa, AL, AL. BACKGROUND: The ability to measure and track changes in muscle and fat is important for practitioners in the Allied Health and Sports Performance fields. An automated image analysis program was recently developed to measure muscle and fat from a single digital image using a smartphone application. However, the reliability of the application has yet to be assessed. PURPOSE: The purpose of this study was to evaluate the test-retest reliability of %Fat estimates from a single digital image when measured on two consecutive days. METHODS: A convenience sample of participants were included in the study (n=12, 83.33% female, 83.33% Caucasian 31.25±10.49 yrs, 24.82 kg/m2). Data collection occurred on two consecutive days with no more than 36 hours between visits. On Day 1, age, gender, and race were assessed via self-report. A full-body image from the posterior view was taken using an iPad Air 2 (Apple Inc., Cupertino, CA) against a white photography backdrop. A light meter (MT-912, Shenzhen Flus Technology Co., Ltd., Shenzhen, China) was used to measure brightness in Lux and ensure that testing conditions were consistent across both days. Participants returned on Day 2 and performed a second %Fat measurement under similar lighting and backdrop conditions. Images were analyzed using an automated smartphone application (made Health and Fitness LLC, Birmingham, AL. version 1.1.3), which provided estimates of %Fat using a proprietary algorithm. A paired samples t-test was used to assess potential mean differences in %Fat across the two trials. The test-retest reliability across the trials was measured using Pearson’s r, and described as weak, moderate, strong, or near-perfect (r=0.2, 0.5, 0.8, or 0.9, respectively). Data are presented as mean± standard deviation, with statistical significance set at p\u3c0.05. RESULTS: No significant mean differences were observed between measurements obtained on Day 1 (27.16±5.08 %Fat) and Day 2 (27.04±5.49 %Fat) (p=0.65). In addition, a near-perfect correlation was observed between the trials (r=0.99, p\u3c0.001). CONCLUSION: Given the negligible difference between measures and the near-perfect correlation, an inexpensive and portable technique to measure %Fat in field settings may be a valuable alternative when traditional assessment techniques are not available. Future research should examine the reliability across multiple camera types, image resolutions, lighting conditions, and color backgrounds

Determinantes nutricionais e sóciodemográficos da variação de peso no pós-parto: uma revisão da literatura Nutritional and socio-demographic determinants of post-partum weight change: a literature review

Trata-se de um estudo de revisão sobre os fatores nutricionais e sócio-demográficos da variação de peso no pós-parto. Foi realizada uma busca bibliográfica nas bases de dados eletrônicas Scientific Eletronic Library On-line (SciELO), Literatura Latino-Americana e do Caribe em Ciências da Saúde (LILACS) e Medical Literature Analysis and Retrieval System Online (MEDLINE) referente a literatura publicada na última década (1997-2008). Treze artigos, um informe técnico e dois livros considerados relevantes sobre o assunto e publicados anteriormente ao ano 1997 foram citados na revisão. A revisão priorizou estudos de ensaios clínicos randomizados e de seguimento realizados com gestantes e mulheres no pós-parto. Os resultados obtidos mostram como principais fatores associados com a variação de peso no pós-parto o ganho de peso gestacional acima das recomendações do Institute of Medicine, Índice de Massa Corporal Pré-Gestacional > 25 kg/m2, dieta, tempo e intensidade do aleitamento materno e os fatores sócio-demográficos: raça negra, primiparidade, idade materna, baixa renda e baixa escolaridade. A prática regular de atividade física é recomendada como uma estratégia para evitar o ganho de peso excessivo e melhorar a perda de peso durante o pós-parto. No Brasil não existe uma estratégia nacional para prevenir o ganho de peso excessivo e garantir a adequada perda de peso nesse período. Durante o pós-parto, a maioria das ações de saúde visa basicamente garantir o aleitamento materno.<br>This study is a review of nutritional and sociodemographic factors determining post-partum weight variation. A bibliographical search was carried out on the electronic databases Scientific Eletronic Library On-line (SciELO), Latin-American and Caribbean Literature on Health Sciences (LILACS) and Medical Literature Analysis and Retrieval System Online (MEDLINE) for titles published in the past decade (1997-2008). Thirteen articles, one technical note and two books considered relevant to the subject and published prior to 1997 are also cited in the review. The review prioritized studies involving randomized clinical trials and follow-up carried out among pregnant and post-partum women. The results show that the following are the main factors associated with post-partum weight variation: gestational weight gain above the recommendations of the Institute of Medicine, Pregestational Body Mass > 25 kg/m2, diet, duration and intensity of breast-feeding and socio-demographic factors, such as being black, having given birth only once, the age of the mother, low income and low schooling. Regular physical activity is recommended as a strategy for avoiding excessive weight gain and improving weight loss during post partum. In Brazil, there is no national strategy for preventing excessive weight gain and ensuring adequate weight loss during this period. During post-partum, most health service actions are restricted to ensuring that mothers breastfeed