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%.

Warm- and fatigue in skill acquisition and performance.

Two experiments examined the effects of preliminary exercise on performance and learning of the Fitts' reciprocal tapping task. In the first experiment preliminary exercise was performed with either the preferred or nonpreferred arm. The tapping task was completed with the preferred by both groups. Low levels of preliminary exercise resulted in heightened performance for both groups, but higher levels resulted in a decrement for the group using the preferred arm. An arousal-plus-fatigue hypothesis can explain the results. A subsequent post-test without preliminary exercise showed no difference between the groups, indicating an effect on performance and not learning. In the second experiment preliminary exercise was provided by treadmill running to exhaustion. Again, a facilitatory effect of exercise was demonstrated on tapping performance even after exhaustive levels of running.