New equations improve NIR prediction of body fat among high school wrestlers

Study Design: Methodologic study to derive prediction equations for percent body fat (%BF). Objectives: To develop valid regression equations using NIR to assess body composition among high school wrestlers. Background: Clinicians need a portable, fast, and simple field method for a ssessing body composition among wrestlers. Near-infrared photospectrometry (NIR) meets these criteria, but its efficacy has been challenged. Methods and Measures: Subjects were 150 high school wrestlers from 2 Midwes tern states with mean +/- SD age of 16.3 +/- 1.1 yrs, weight of 69.5 +/- 11 .7 kg, and height of 174.4 +/- 7.0 cm. Relative body fatness (%BF) determin ed from hydrostatic weighing was the criterion measure, and NIR optical den sity (OD) measurements at multiple sites, plus height, weight, and body mas s index (BMI) were the predictor variables. Results: Four equations were developed with multiple R(2)s that varied from .530 to .693, root mean squared errors varied from 2.8% BF to 3.4% BF, and prediction errors varied from 2.9% BF to 3.1% BF. The best equation used O D measurements at the biceps, triceps, and thigh sites, BMI, and age. The r oot mean squared error and prediction error for all 4 equations were equal to or smaller than for a skinfold equation commonly used with wrestlers. Conclusion: The results substantiate the validity of NIR for predicting % B F among high school wrestlers. Cross-validation of these equations is warra nted.