Purpose: The purpose of this study was to determine how differences in hydration states and ion content of hydrating fluids affected bioelectrical impedance (BI) and hydrostatic weighing (HW) measurements. Methods: Fifteen athletic subjects aged 19-56 yr were recruited. Relative body fat (%), fat- weight (FW), and fat-free weight (FW) were assessed using BI and HW under normal conditions (N), hypohydration (HPO), rehydration (RHY), and superhydration (SHY) states. During the RHY and SHY trial periods, subjects were hydrated with either distilled water or an electrolyte solution (ELS). HPO and SHY levels were set at 3% of each person's normally hydrated body weight. Results: Comparison between the distilled water and the ELS trials indicated that hydration solution had no effect on BI or HW. Thus, the results presented are the trial means of both hydration solutions combined. Both BI and HW were shown to be highly test-retest reliable (r-values: 0.96 and 0.99, respectively). The effects of exercise induced HPO followed by RHY on body composition values indicated that HW was very stable across measurement periods while BI was not. From N to the HPO state, BI %BF declined from 14.4 ± 5.3% to 12.3 ± 5.3%, respectively. After RHY, BIA %BF increased to 15.5 ± 5.8%. Similar findings occurred when subjects were superhydrated (N-BI = 13.2 ± 5.3%; SHY-BI = 15.4 ± 5.6%). With a comparison of the intercepts and slopes of HW and BIA for the N and SHY states, it was clear hydration status significantly affected the intercepts (HW: 0.37 vs. BI: 1.85) and not the slopes (HW: 1.00 vs BI: 0.99). As a result, a majority of all fluid changes were interpreted as FW by BI. During HPO, 82% of the weight loss was considered FW while during RHY or SHY, 128% and 85% of the water weight regain/gain was considered FW. Conclusion: These results indicate that BI is not a valid technique in athletes, especially when wanting to determine body composition effects of training/detraining. This study indicates that even small fluid changes such as those that occur with endurance training may be interpreted incorrectly as changes in an athlete's body fat content.

This study's purpose was to determine the validity of near-infrared interactance (NIR) and bioelectric impedance (BIA) in tracking changes in body composition over 12 wk of either a high intensity endurance (ET) or resistance (RT) training program in nondieting weight-stable untrained males. Prior to and following the control or training period, each subject completed a series of body composition analyses including hydrostatic weighing (HW) with a measurement of residual volume; anthropometric measurements including height, weight, skinfold, and girth; BIA measurement; and NIR measurements. Based on the HW results, there were no significant body composition changes in the control group. For the ET group, a significant decline in relative body fat resulted from a reduction in fat weight (FW) with no change in fat-free weight (FFW). In the RT group, both a significant decline in FW and an increase in FFW contributed to this group's decline in relative body fat. Tracking changes in relative body fat, FW, and FFW, skinfolds agreed reasonably well with HW in all groups while BIA and NIR did not always track body composition changes well. For example, SF and BIA were significantly correlated with the changes in FFW (HW = + 4.1%, SF = + 4.5%, BIA = + 3.1% NIR = - 0.7%) observed in the RT group compared to HW (SF: r-value = 0.45, SEE = 2.5; BIA; r = 0.33, SEE = 3.4) while the NIR measurements were nonsignificant (r = 0.09, SEE = 5.0). Interestingly, NIR underestimated the gain in FFW in the resistance trained group while BIA underestimated the changes in relative body fat, FW, and FFW in the endurance trained group. Based on these results, BIA aim NIR appear not to be appropriate measurement tools for tracking body composition changes in endurance and resistance training individuals respectively.

The purpose of this investigation was to determine the effects of a four day creatine load and simultaneous energy restriction on muscle creatine content, exercise performance, and body composition in 24 male recreational resistance trainers, age 18-26. Sixteen subjects were randomly divided into placebo (Pl, n=8) and creatine supplement (CrS, n=8) groups. Control (C, n=8) subjects of the same age were recruited separately g à d-1 to complete the performance and body composition tests while consuming their normal diet. The CrS group was administered 20 g à d-1 of creatine monohydrate (Cr) mixed with 5 g à d-1 of sucrose, while the Pl group was administered 25 of sucrose. Both CrS and Pl consumed a formula diet of 75.3 kJ (18 kcal) à kg-1 à d-1 for 4 d. Testing before and after energy restriction consisted of a repeated sprint cycle performance test (10 sprints of 6s, with 30s rest), hydrostatic weighing, and resting needle muscle biopsy. Testing revealed that subjects in CrS and Pl demonstrated significant decreases in body weight and % body fat (%BF) with no difference between groups. However, Pl demonstrated a significantly greater % loss in FFM (2.4 ± 0.25%) compared to CrS (1.4 ± 0.4%) (p<0.05). The muscle fuel stores of CrS and Pl responded significantly to the diet. Significant increases in muscle total Cr (p<0.01), free Cr (p<0.01), and CrP (p<0.05) of 16.5%, 16.8%, and 16% respectively were demonstrated by CrS over the energy restriction period, while Pl demonstrated significant decreases of 7.2% and 8.2% respectively in muscle total Cr (p<0.01) and free Cr (p<0.05). There were no significant differences between groups for performance during the cycle test, however, there were trends toward group by time interactions for performance enhancement in CrS relative to Pl, as total work (p=0.078) and work capacity (p=0.058) increased 3.8 ± 2.2% in CrS and decreased 0.5 ± 0.4% in Pl. It was concluded that short-term energy restriction resulted in decreased muscle Cr storage, and that Cr supplementation during energy restriction increased muscle Cr and CrP stores. Consumption of Cr allowed CrS to lose a significantly lower % FFM compared to Pl. Cr supplementation resulted in trends toward improved performance in CrS relative to Pl after energy restriction, but did not influence losses in body weight or %BF. / Master of Science

The present study had as objective to analyze the accuracy of different indicators of the nutritional status of adults of both sexes, having as reference method the hydrostatic weighing (HW). A total of 280 subjects (210 men and 70 women), aged between 17 and 48 years old, were investigated. The results of body fat percentage (%BF) obtained through the University of Navarra-Body Adiposity Estimator (CUN- BAE), body adiposity index (BAI), skinfold estimation equations (E-DC) and bioelectrical impedance (BIA). We also analyzed the results of the body mass index (BMI), new body mass index (BMI2.5), body fat mass index BFMI and the body mass index adjusted by the fat mass (BMIfat), all of them using HW as the reference method. The results indicated that no significant differences were observed between the %BF measures of the E-DC and BIA indicators and the HW for the male group; however, for the female group, despite the analyzes indicating agreement, the %BF values presented statistically different from those obtained with the reference method. The BAI presented an acceptable estimation error when evaluating the female group and the CUN-BAE presented a tendency to overestimate the values of %BF, in both sexes. On the other hand, the BFMI presented the highest agreement value, but classified as discrete (k=0.21). The other indexes presented small agreement with the results of the reference method (k <0.20). It is possible to conclude that, in a general way, the E-DC and BIA indicators were the ones that presented the best results, with the E-DC being more efficient to evaluate the male subjects. In addition, none of the indexes investigated showed good accuracy in assessing the nutritional status of adults, although they showed results of correlation with the reference method, did not reach the minimum criterion of agreement. / O presente estudo teve como objetivo analisar a acurácia de diferentes indicadores do estado nutricional de adultos, de ambos os sexos, tendo como método de referência a pesagem hidrostática (PH). Foram investigados 280 sujeitos (210 homens e 70 mulheres), com idade entre 17 e 48 anos, dos quais se analisou os resultados de percentual de gordura corporal (%GC) obtidos através do Clínica Universidad de Navarra-Body Adiposity Estimator (CUN-BAE), do índice de adiposidade corporal (IAC), das equações de estimativa a partir de dobras cutâneas (E-DC) e da impedância bioelétrica (IB). Também foram analisados os resultados do Índice de Massa Corporal (IMC), do novo Índice de Massa Corporal (IMC2,5), do Índice de Massa Gorda (IMG) e do Índice de Massa Corporal ajustado pela Massa Gorda (IMCgordura), todas as análises tendo como método de referência a PH. Os resultados indicaram que não foram observadas diferenças significativas entre as medidas de %GC dos indicadores E-DC e IB e a PH para o grupo masculino, no entanto, para o grupo feminino, apesar das análises indicarem concordância, os valores de %GC apresentaram-se estatisticamente diferentes dos obtidos com o método de referência. O IAC apresentou erro de estimativa aceitável ao avaliar o grupo feminino e o CUN-BAE apresentou tendência de superestimar os valores de %GC, em ambos os sexos. Por outro lado o índice IMG apresentou o maior valor de concordância, porém classificado como discreto (k = 0,21). Já os demais índices apresentaram concordância pequena com os resultados do método de referência (k<0,20). É possível concluir que, de uma forma geral, os indicadores E-DC e IB foram os que apresentaram os melhores resultados, sendo que o E-DC se mostra mais eficiente para avaliar indivíduos do sexo masculino. Além disso, nenhum dos índices investigados apresentou boa acurácia para avaliar o estado nutricional de adultos, pois apesar de mostrarem resultados de correlação com o método de referência, não atingem o critério mínimo de concordância.

Body composition has been shown to be an important indicator of health, since many chronic diseases are related to excess adiposity. In this context the appropriate assessment is required in order to obtain the correct diagnosis in terms of nutritional status. Thus, the aim of this study was to analyze the relationship between the components of body composition of college students in the city of Santa Maria, RS obtained from hydrostatic weighing (HW), bioelectrical impedance (BI) and anthropometry and agreement between shown diagnostics. The study included 164 college students (104 men and 60 women) aged between 18 and 30 years. For the determination of body composition, subjects were evaluated by means of HW, BI and anthropometry (weight, height, skinfolds thickness, body circumferences, and bone breadths), and analyzed 48 equations (32 generalized and 16 specific) for review the percentage of body fat (%BF), 7 equations of lean body mass (LBM), two of muscle mass (MM) and two bone mass (BM). Descriptive statistics, the Kolmogorov - Smirnov test, the t test for dependent samples, the Pearson correlation coefficient , the standard error of estimate, the total error and constant error of the scatter diagram was used as well, Bland - Altman (1986) and the kappa coefficient to verify the concordance of the results. The level of significance was set at 5%. Data analysis was performed with SPSS, version 14.0. The average %BF was found to be 16.3% in men and 26.3% women. As for the agreement, the generalized equations demonstrated greater power of the relative body fat, 16 equations (9 men and 7 for women) Petroski (1995) showed no significant difference data obtained using the method, as well as an equation Guedes and Guedes (1991) for women and BI for men. The kappa coefficient of concordance observed was low (≤0.44) having few overlapping diagnoses. MCM obtained by different equations differed from results obtained with the criterion method, as compared to BI (body composition analyzer), only the results obtained for men did not differ from the criterion method. The equations of MM Janssen et al. (2000) and Lee et al. (2000) showed a correlation coefficient of r = 0.72 for men and r = 0.76 for women, and no statistical difference was observed. BM already obtained by means of equations Von Döbeln modified by Rocha (1975) and Martin (1991) showed statistically different results. Based on the results we conclude that: a) for the determination of %BF equation Petroski (1995) that uses variables as the sum of nine skinfolds thickness and age, for men, and employing the sum of three skinfold thickness and age, for women were those that showed the best results in agreement with the reference method, however, the diagnostic showed up just the same; b) LBM provided by body composition analyzer proved acceptable for men, whereas for females the results were not satisfactory; c) the MM results presented good agreement between the equations for both genders; and d) the equations of BM demonstrate different results, both when analyzing the female group, as the male group. / A composição corporal tem se mostrado um importante indicador de saúde, visto que muitas doenças crônicas estão relacionadas ao excesso de adiposidade. Neste contexto a avaliação adequada é necessária, com o intuito de se obter o diagnóstico correto em termos de estado nutricional. Desse modo, o objetivo deste estudo foi analisar a relação entre os componentes da composição corporal de estudantes universitários da cidade de Santa Maria, RS obtidos a partir da pesagem hidrostática (PH), da impedância bioelétrica (IB) e da antropometria e a concordância entre os diagnósticos evidenciados. Participaram deste estudo 164 universitários (104 homens e 60 mulheres) com idade entre 18 e 30 anos. Para a determinação da composição corporal, os indivíduos foram avaliados por meio da PH, da IB e da antropometria (massa corporal, estatura, dobras cutâneas, perímetros corporais e diâmetros ósseos), sendo analisadas 48 equações (32 generalizadas e 16 específicas) para avaliação do percentual de gordura corporal (%GC), 7 equações de massa corporal magra (MCM), duas de massa muscular (MM) e duas de massa óssea (MO). Foi utilizada a estatística descritiva, o teste de normalidade de Kolmogorov-Smirnov, o teste t para amostras dependentes, o coeficiente de correlação de Pearson, o erro padrão de estimativa, o erro total e o erro constante, bem como, o diagrama de dispersão de Bland-Altman (1986) e o coeficiente kappa para verificar a concordância dos resultados. O nível de significância adotado foi de 5%. A análise dos dados foi feita com o programa SPSS, versão 14.0. O %GC médio encontrado foi de 16,3% nos homens e 26,3% nas mulheres. Com relação à concordância, as equações generalizadas demonstraram maior poder de precisão da gordura corporal relativa, 16 equações (9 para homens e 7 para mulheres) de Petroski (1995) não apresentaram diferença significativa dos dados obtidos com o método critério, bem como uma equação de Guedes e Guedes (1991) para as mulheres e a IB para os homens. O coeficiente de concordância kappa observado foi baixo (≤0,44), apresentando poucos diagnósticos coincidentes. A MCM obtida pelas diferentes equações diferiu estatisticamente do resultado obtido com o método critério, já em relação a IB (analisador de composição corporal), apenas os resultados obtidos para os homens não diferiu do método critério. As equações de MM de Janssen et al. (2000) e Lee et al. (2000) apresentaram coeficiente de correlação de r=0,72 para os homens e r=0,76 para as mulheres, bem como não foi observada diferença estatística. Já a MO obtida por meio das equações de Von Döbeln modificada por Rocha (1975) e de Martin (1991) demonstraram resultados estatisticamente diferentes. Com base nos resultados obtidos foi possível concluir que: a) para a determinação do %GC a equação de Petroski (1995) que utiliza como variáveis o somatório da espessura de nove dobras cutâneas e a idade, para os homens, e a que emprega o somatório da espessura de três dobras cutâneas e a idade, para as mulheres, foram as que demonstraram os melhores resultados de concordância com o método de referência, no entanto, os diagnósticos apresentaram-se pouco coincidentes; b) a MCM fornecida pelo analisador de composição corporal mostrou-se aceitável para os homens, já para o grupo feminino os resultados obtidos não foram satisfatórios; c) os resultados de MM apresentaramse concordantes entre as equações em ambos os sexos; e d) as equações de MO demonstram resultados distintos, tanto ao analisar o grupo feminino, quanto o grupo masculino.