The gymnasts in the present study were approximately the same height and body weight (BW) but had less%fat than reference adolescent females of the same age (7). Compared with gymnasts of approximately the same age (4,23,35), the present subjects were taller, heavier, and had greater%fat. These differences in BW and%fat between samples of gymnasts may have been attributable to differences in training status. The subjects of Claessens et al. (4), Moffatt et al. (23), and Thorland et al.(35) were highly trained, while the present sample was measured during the preseason and prior to competition.
The following criteria were used in the present study to evaluate the results of the cross-validation analyses(6,9,14,17,29): (a) there should be a nonsignificant mean difference (CE) between the criterion and predicted%fat values; (b) the criterion and predicted%fat values should be significantly correlated; (c) there should be close agreement between the SD values of criterion and predicted%fat; (d) the SEE and TE values should be≤4%fat, and there should be a close similarity between the SEE and TE because it reflects the relationship between the regression line of criterion vs predicted%fat and the line of identity; and (e) if all other criteria are equal, equations that use the sum of skinfolds are preferred over those that use individual skinfold measures due to less intertester error. While all of these criteria should be considered, Sinning et al. (29) have stated that the TE is the best single criterion for determining the true difference between criterion and predicted%fat values.
Previous studies have cross-validated EQ 1-4, 6, and 8-11 on adolescent athletes (36,37), college athletes(20), and nonathletic children and adolescents(12). Thorland et al.(36,37) report TE values for EQ 1, 2, and 8-11 that ranged from approximately 2.2 (EQ 9) to 7.3 (EQ 11)%fat in samples of highly trained adolescent athletes (age range, 11.17-19.58 yr). As in the present study, EQ 1, 2, 9, and 10 resulted in low TE values of approximately 2.5, 2.6, 2.2, and 2.4%fat, respectively, while the equation (EQ 8) of Sloan et al. (32) has a TE of 4%fat(36,37). Mayhew et al. (20) cross-validated EQ 1-3, 8, and 11 on a sample of 111 college athletes([horizontal bar over]X age ± SD = 19.66 ± 1.24 yr) and found TE values of approximately 4, 4.3, 4.2, 3.9, and 5.1%fat, respectively. Except for EQ 11, these values were higher than those from the present investigation(Table 4). Janz et al. (12) report TE values of approximately 3.8 and 3.5%fat for EQ 6 and 7, respectively, in a sample of 55 children and adolescents ([horizontal bar over]X age ± SD= 11.5 ± 1.8 yr). These values were 0.4 to 1.4%fat less than those from the present investigation (Table 4).
In the present study, the quadratic sum-of-three skinfold equation (EQ 10) of Thorland et al. (37) satisfied the most cross-validation criteria and, therefore, is recommended for estimating body composition in high school female gymnasts. The other six equations with TE values ≤3.9%fat (EQ 1-3 and 7-9) do not meet as many of the criteria but should be considered acceptable alternatives to EQ 10. EQ 10 resulted in a nonsignificant CE (0.6%fat; P > 0.0045), as well as low SEE(3.1%fat) and TE values (3.4%fat). Furthermore, the SD of predicted%fat(4.8%fat) was similar to the SD of%fat from UWW (4.5%fat), and EQ 10 uses the sum of skinfolds, which is preferred over individual skinfold measures such as those used in EQ 3 and 8 due to less intertester error(9). Compared with EQ 9, EQ 10 uses fewer skinfold measures (3 vs 7 skinfolds) and more closely approximated the%fat distribution from UWW (SD from UWW = 4.5%fat; EQ 9 = 5.4%fat; EQ 10 = 4.8%fat).
A preseason estimation of body composition using EQ 10 may be valuable to coaches and high school female gymnasts for determining a safe minimal competitive body weight and reducing the use of the potentially pathogenic behaviors associated with excessive weight loss. It has been recommended that high school wrestlers compete at not less than 5-7%fat(1,38). Females, however, have essential fat (bone marrow, spinal cord, liver, heart, spleen, kidneys, etc.) plus sex-specific fat (breasts, genitals, lower body subcutaneous, intramuscular, etc.) levels that total approximately 9-14%fat (2,13). Furthermore, it has been suggested that 12-14%fat represents a realistic lower limit of fatness for maintaining good health in females(22). This range is consistent with the mean%fat(13.1-14.8%fat) of adolescent female gymnasts at their optimum training level(23,35). Therefore, it is recommended that: (a) EQ 10 be used for a preseason assessment of body composition for high school female gymnasts if a laboratory procedure such as UWW is not available, (b) a minimal body weight at not less than 12%fat be determined from the preseason body composition assessment, and (c) high school female gymnasts receive medical clearance before being allowed to compete at less than 12%fat. Using the mean data from the present study, the minimal body weight from UWW at the recommended 12%fat would be 50.5 kg (fat-free weight/0.88). According to EQ 10, the predicted minimal body weight would be 50.9 kg (±1 TE of 3.4%fat = 48.8-53 kg).
1. American College of Sports Medicine. Position statement on weight loss in wrestlers. Sports Med. Bull.
2. Behnke, A. R. New concepts of height-weight relationships. In: Obesity
, N. L. Wilson (Ed.). Philadelphia: F. A. Davis, 1969, pp. 25-53.
3. Brozek, J., F. Grande, J. T. Anderson, and A. Keys. Densitometric analysis of body composition: revision of some quantitative assumptions. Ann. N. Y. Acad. Sci.
4. Claessens, A. L., R. M. Malina, J. Lefevre, et al. Growth and menarcheal status of elite female gymnasts. Med. Sci. Sports Exerc.
5. Clark, R. R., J. M. Kuta, and R. A. Oppliger. The Wisconsin wrestling minimal weight project: cross-validation of prediction equations. Pediatr. Exerc. Sci.
6. Graves, J. E., M. L. Pollock, A. B. Calvin, M. Van Loan, and T. G. Lohman. Comparison of different bioelectrical impedance analyzers in the prediction of body composition. Am. J. Hum. Biol.
7. Haschke, F. Body composition during adolescence. In:Body Composition Measurements in Infants and Children
, W. J. Klish and N. Kretchmer (Eds.). Columbus, OH: Ross Laboratories, 1989, pp. 76-82.
8. Jackson, A. S. and M. L. Pollock. Practical assessment of body composition. Physician Sportsmed.
9. Jackson, A. S., M. L. Pollock, and L. R. Gettman. Intertester reliability of selected skinfold and circumference measurements and percent fat estimates. Res. Q
. 49:546-551, 1978.
10. Jackson, A. S., M. L. Pollock, J. E. Graves, and M. T. Mahar. Reliability and validity of bioelectrical impedance in determining body composition. J. Appl. Physiol.
11. Jackson, A. S., M. L. Pollock, and A. Ward. Generalized equations for predicting body density of women. Med. Sci. Sports Exerc.
12. Janz, K. F., D. H. Nielsen, S. L. Cassady, J. S. Cook, Y. T. Wu, and J. R. Hansen. Cross-validation of the Slaughter skinfold equations for children and adolescents. Med. Sci. Sports Exerc.
13. Katch, V. L., B. Campaigne, P. Freedson, S. Sady, F. I. Katch, and A. R. Behnke. Contribution of breast volume and weight to body fat distribution in females. Am. J. Phys. Anthropol.
14. Katch, F. I. and V. L. Katch. Measurement and prediction errors in body composition assessment and the search for the perfect prediction equation. Res. Q. Exerc. Sport
15. Katch, F. I. and W. D. McArdle. Prediction of body density from simple anthropometric measurements in college-age men and women.Hum. Biol.
16. Keppel, G. Design and Analysis: A Researcher's Handbook
, 3rd Ed. Englewood Cliffs, NJ: Prentice-Hall, 1991, p. 167.
17. Lohman, T. G. Skinfolds and body density and their relationship to body fatness: a review. Hum. Biol.
18. Lohman, T. G. Applicability of body composition techniques and constants for children and youths. In: Exercise and Sport Sciences Reviews
. New York: Macmillian, 1986, pp. 325-357.
19. Lohman, T. G. Advances in Body Composition Assessment
. Champaign, IL: Human Kinetics, 1992, pp. 43-45.
20. Mayhew, J. L., B. A. Clark, B. C. Mckeown, and D. H. Montaldi. Accuracy of anthropometric equations for estimating body composition in female athletes. J. Sports Med.
21. Mayhew, J. L., F. C. Piper, J. A. Koss, and D. H. Montaldi. Prediction of body composition in female athletes. J. Sports Med. 23:333-340, 1983.
22. McArdle, W. D., F. I. Katch, and V. L. Katch.Exercise Physiology: Energy, Nutrition, and Human Performance
. Philadelphia: Lea and Febiger, 1991, p. 603.
23. Moffatt, R. J., B. Surina, B. Golden, and N. Ayres. Body composition and physiological characteristics of female high school gymnasts. Res. Q. Exerc. Sport
24. Mukherjee, D. and A. F. Roche. The estimation of percent body fat by maximum R2
regression equations. Hum. Biol.
25. Nielsen, D. H., S. L. Cassady, K. F. Janz, J. S. Cook, J. R. Hansen, and Y. T. Wu. Criterion methods of body composition analysis for children and adolescents. Am. J. Hum. Biol.
26. Oppliger, R. A., R. D. Harms, D. E. Herrmann, C. M. Streich, and R. R. Clark. Grappling with weight cutting: the Wisconsin wrestling minimum weight project. Physician Sportsmed.
27. Petrie, T. A. and S. Stoever. The incidence of bulimia nervosa and pathogenic weight control behaviors in female collegiate gymnasts.Res. Q. Exerc. Sport
28. Rosen, L. W. and D. O. Hough. Pathogenic weight-control behaviors of female college gymnasts. Physician Sportsmed.
29. Sinning, W. E., D. G. Dolny, K. D. Little, et al. Validity of “generalized” equations for body composition analysis in male athletes. Med. Sci. Sports Exerc.
30. Slaughter, M. H., T. G. Lohman, R. A. Boileau, et al. Skinfold equations for estimation of body fatness in children and youth.Hum. Biol.
31. Slaughter, M. H., T. G. Lohman, R. A. Boileau, et al. Influence of maturation on relationship of skinfolds to body density: a cross-sectional study. Hum. Biol.
32. Sloan, A. W., J. J. Burt, and C. S. Blyth. Estimation of body fat in young women. J. Appl. Physiol.
33. Teitz, C. C. Sports medicine concerns in dance and gymnastics. Pediatr. Clin. North Am.
34. Thomas, T. R. and P. L. Cook. A simple inexpensive method for estimating underwater weight. Br. J. Sports Med.
35. Thorland, W. G., G. O. Johnson, T. G. Fagot, G. D. Tharp, and R. W. Hammer. Body composition and somatotype characteristics of Junior Olympic athletes. Med. Sci. Sports Exerc.
36. Thorland, W. G., G. O. Johnson, G. D. Tharp, T. G. Fagot, and R. W. Hammer. Validity of anthropometric equations for the estimation of body density in adolescent athletes. Med. Sci. Sports Exerc.
37. Thorland, W. G., G. O. Johnson, G. D. Tharp, T. J. Housh, and C. J. Cisar. Estimation of body density in adolescent athletes.Hum. Biol.
38. Thorland, W. G., C. M. Tipton, T. G. Lohman, et al. Midwest wrestling study: prediction of minimal weight for high school wrestlers. Med. Sci. Sports Exerc.
39. Wilmore, J. H. A simplified method for determination of residual lung volume. J. Appl. Physiol.
40. Wilmore, J. H. and A. R. Behnke. An anthropometric estimation of body density and lean body weight in young women. Am. J. Clin. Nutr.
BODY COMPOSITION; FEMALE ATHLETES; CROSS-VALIDATION; GYMNASTICS