Body composition changes in elite male bodybuilders during preparation for competition.

Anthropometric profiles together with a 4 compartment criterion model of body composition analysis (total body water, bone mineral, fat and residual masses via a combination of deuterium dilution, dual-energy x-ray absorptiometry and hydrodensitometry) were conducted on 3 elite male bodybuilders 10 wk and then 5 d before competition. A mean body mass reduction from 99.70 (Quetelet's Index = 31.6 kg/m2) to 92.79 kg (Quetelet's Index = 29.2 kg/m2) was accompanied by a decline in the sum of 8 skinfold thicknesses (triceps, subscapular, biceps, iliac crest, supraspinale, abdominal, front thigh and medial calf) from 51.1 to 36.7 mm. The 4 compartment body composition model indicated that there were reductions of: percent body fat (%BF) from 9.1 to 5.0%, fat free mass (FFM) from 90.60 to 88.14 kg and fat mass (FM) from 9.10 to 4.65 kg. Sixty-four percent of the 6.91 kg loss in body mass therefore came from the FM. The 2 compartment hydrodensitometric model yielded higher %BFs (initial = 11.2; final = 7.1) than the 4 compartment model (initial = 9.1; final = 5.0) which is theoretically more valid because it controls for biological variability in the percentages of water and bone mineral in the FFM. Nevertheless, both models registered decreases of 4.1%BF.

The Drinkwater-Ross anthropometric fractionation of body mass: comparison with measured body mass and densitometrically estimated fat and fat-free masses.

The Drinkwater-Ross anthropometric fractionation of body mass (mass = sigma skeletal, residual, fat and muscle masses), lean body mass (LBM = sigma skeletal, residual and muscle masses) and fat mass (FM) were compared with the measured body mass, together with the densitometrically estimated fat-free mass (FFM) and fat mass (FM), of 205 male (mean +/- S.D.: 74.66 +/- 10.55 kg; 10.1 +/- 3.7% BF by densitometry) and 177 female (mean +/- S.D.: 59.14 +/- 8.85 kg; 18.5 +/- 5.1% BF by densitometry) South Australian State representatives in a variety of sports. Most absolute differences (d) between the measured body masses and those resultant from the sum of the four fractionated masses (male: d = 2.15 kg or 2.9%; female: d = 1.27 kg or 2.2%) were within what one would expect from random day-to-day variation. However, this was not so for the comparisons between the fractionated LBM (male: d = 2.54 kg or 3.8%; female: d = 2.45 kg or 5.2%) and FM scores (male: d = 1.67 kg or 30.0%; female: d = 2.40 kg or 20.0%) and their densitometric counterparts. These differences are probably related to a combination of the densitometric and fractionation assumptions.

Relative body fat and anthropometric prediction of body density of female athletes.

Ninety-one percent (n = 182) of the female members of South Australian representative squads in 14 sports volunteered to act as subjects. Twenty-seven percent of them had represented Australia. The underwater weighing method together with the measurement of residual volume (RV) by helium dilution were used to determine body density (BD); the percent body fat (% BF) was then computed according to Siri. A stepwise multiple regression analysis yielded a correlation coefficient (R) of 0.863 between the criterion (BD) and the best weighted sum of predictors (anthropometric variables): BD (g X cm-3) = 1.14075-0.04959 (log10 sigma triceps, subscapular, supraspinale and calf skinfolds in mm) + 0.00044 (age in decimal years)-0.000612 (waist girth in cm) + 0.000284 (height in cm)-0.000505 (gluteal girth in cm) + 0.000331 (breast girth in cm). Only those predictors which resulted in a statistically significant increase in R (p less than or equal to 0.05) were included. The standard error of estimate of 0.00597 g X cm-3 was equivalent to 2.7% BF at the mean. This equation was shown to be largely population specific. There was a range of 7.6-35.8% of BF and the overall mean 18.5% was significantly lower (p less than 0.001) than that of 23.4% obtained on a moderately active reference sample of similar age (n = 135). If group sizes of only one or two are regarded as too small for meaningful comparison, then the lowest mean of 13.5% was achieved by the long-distance runners (n = 14). The highest averages were registered by the heavyweight rowers (24.2%; n = 7) and soccer players (22.0%; n = 11). The overall average for games players (n = 107) was 19.4%.