I. Skinfold thickness, body circumferences and body density were measured in samples of 308 and ninetyfive adult men ranging in age from 18 to 61 years.2. Using the sample of 308 men, multiple regression equations were calculated to estimate body density using either the quadratic or log form of the sum of skinfolds, in combination with age, waist and forearm circumference.3. The multiple correlations for the equations exceeded 0.90 with standard errors of approximately +oao73 g/ml.4. The regression equations were cross validated on the second sample of ninety-five men. The correlations between predicted and laboratory-determined body density exceeded 0.90 with standard errors of approximately 0.0077 g/ml.5. The regression equations were shown to be valid for adult men varying in age and fatness.
In brief: The assessment of body composition has become an important method for determining a desirable body weight of adults and athletes. Hydrostatic weighing is a popular and valid method, but it is often not feasible for the clinical setting or for mass testing; thus, anthropometry has become the preferred method. This article reviews the scientific basis for generalized body composition prediction equations and provides methods for evaluating body composition. The authors recommend using a sum of three skinfolds (triceps, chest, and subscapula for men and triceps, abdomen, and suprailium for women) and give detailed instructions for securing accurate measurements of body fat.
The purpose of this study was to investigate the time course of skeletal muscle adaptations resulting from high-intensity, upper and lower body dynamic resistance training (WT). A group of 17 men and 20 women were recruited for WT, and 6 men and 7 women served as a control group. The WT group performed six dynamic resistance exercises to fatigue using 8-12 repetition maximum (RM). The subjects trained 3 days a week for 12 weeks. One-RM knee extension (KE) and chest press (CP) exercises were measured at baseline and at weeks 2, 4, 6, 8, and 12 for the WT group. Muscle thickness (MTH) was measured by ultrasound at eight anatomical sites. One-RM CP and KE strength had increased significantly at week 4 for the female WT group. For the men in the WT group, 1 RM had increased significantly at week 2 for KE and at week 6 for CP. The mean relative increases in KE and CP strength were 19% and 19% for the men and 19% and 27% for the women, respectively, after 12 weeks of WT. Resistance training elicited a significant increase in MTH of the chest and triceps muscles at week 6 in both sexes. There were non-significant trends for increases in quadriceps MTH for the WT groups. The relative increases in upper and lower body MTH were 12%-21% and 7%-9% in the men and 10%-31% and 7%-8% in the women respectively, after 12 weeks of WT. These results would suggest that increases in MTH in the upper body are greater and occur earlier compared to the lower extremity, during the first 12 weeks of a total body WT programme. The time-course and proportions of the increase in strength and MTH were similar for both the men and the women.
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