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The subjects were 170 moderately and severely mentally retarded men who were divided into two groups. The first group was used to formulate a new prediction equation and the second group was used to cross-validate and ascertain the stability of the derived equation. The prediction equation, employing waist and forearm circumferences, height and weight as predictors, and estimated percent body fat calculated by the generalized regression equation of Jackson and Pollock (1978) as the criterion measure, was formulated using a stepwise multiple regression analysis. A multiple R value of .86 was obtained for the derived equation with a standard error of estimate value of 3.35. The equation was cross-validated on the second sample to ascertain its stability. An r of .81 and a standard error of estimate of 4.41 was obtained between the subjects’ estimated percent body fat, using the new equation, and the criterion measure. This simplified equation provides practitioners with an accurate, reliable, and inexpensive method of estimating percent body fat for adult mentally retarded males.

The purpose of the present study was to determine the validity of near-infrared interactance (NIR) estimates of percent body fat (% fat) using Futrex-5000, Futrex-5000A, and Futrex-1000 instruments in youth wrestlers (age, M ± SD = 11.4 ± 1.5 years) by comparing them to % fat values from underwater weighing. Fifty-eight members of youth wrestling clubs (% fat, M ± SD = 10.7 ± 5.1% fat) volunteered to serve as subjects. The statistical analyses included examination of the constant error (CE), standard error of estimate (SEE), correlation coefficient (r), and total error (TE). The results indicated that the errors (TE = 8.0–16.2% fat) associated with the NIR instruments were too large to be of practical value for estimating % fat in young male athletes. It is recommended that (a) the instrument generated NIR % fat estimates be modified based on the CE values in the present investigation such that the CE = 0, and (b) the modified NIR % fat estimates be cross-validated on independent samples of young male athletes.

Little data exist on the comparison of blood lipids and percent body fat between Down Syndrome and non-DS adults with mental retardation (MR). The following study was undertaken to determine if there were physiological and biochemical differences between these two groups. Subjects included 294 non-DS adults with MR (162 males and 132 females) and 31 adults with Down Syndrome (21 males and 10 females). Level of mental retardation was similar for both groups (males/females, Down vs. non-DS). A two-factor ANOVA with a regression approach was used to analyze the data. Results of the study found that there were no significant differences between the Down Syndrome and non-DS subjects on total cholesterol, HDL cholesterol, LDL cholesterol, triglycerides, or percent body fat. The present study suggests that the composition of lipoproteins and storage of body fat are similar in Down Syndrome and non-DS adults with mental retardation, and that the risk for developing coronary heart disease appears to be the same for both groups.

Body composition assessment techniques provide estimates of percent body fat (%BF), fat mass (FM), and fat-free mass (FFM) based on indirect assessment models and methods. Prediction equations for %BF developed using a two-component model based on adult body composition constants will overestimate %BF in youths, especially prepubescent youths. Body composition prediction equations that have been validated and cross-validated using multiple-component criterion models which include measurements of body density and the water and mineral components of FFM provide the most accurate means for assessment of body composition in youths. Use of appropriate prediction equations and proper measurement techniques, for either bioelectrical impedance or skinfolds, results in body composition estimates with standard errors of estimate (prediction errors) of 3 to 4% BF and 2.0 to 2.5 kg of FFM. Poor measurement technique and inappropriate prediction equations will result in much larger prediction errors.

The aim of this study was to evaluate the effects of a hypertrophic training program during Ramadan on body composition and selected metabolic markers in trained bodybuilders. Sixteen male recreational bodybuilders (9 Ramadan fasters and 7 nonfasters) participated in the study. All visited the laboratory 2 d before the start of Ramadan (Bef-R) and on the 29th day of Ramadan (End-R). In the morning of each session, subjects underwent anthropometric measurement, completed a dietary questionnaire, and provided fasting blood and urine samples. Body mass and body-mass index in nonfasters increased by 2.4% (p = .05 and p = .04, respectively) from Bef-R to End-R but remained unchanged in fasters over the period of the investigation. Fasters experienced an increase in the following parameters from Bef-R to End-R: urine specific gravity (1%, p = .022) and serum concentrations of urea (5%, p = .008), creatinine (5%, p = .007), uric acid (17%, p < .001), sodium (2%, p = .019), potassium (6%, p = .006), chloride (2%, p = .028), and high-density lipoprotein cholesterol (10%, p = .005). However, only serum creatinine and low-density lipoprotein cholesterol increased in nonfasters (3%, p < .001 and 14%, p = .007, respectively) during the same period. Creatinine clearance values of fasters decreased by 3% (p = .03) from Bef-R to End-R. Continuance of hypertrophic training through Ramadan had no effect on body mass and body composition of bodybuilders, but a state of dehydration and reduced renal function were apparent, perhaps because of the restricted opportunity for fluid intake imposed by the study design.