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New equations improve NIR prediction of body fat among high school wrestlers
R A Oppliger1, R R Clark, D H Nielsen
1Physical Therapy Graduate Program, The University of Iowa, Iowa City 52242-1997, USA. bob-oppliger@uiowa.edu
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 assessing 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 Midwestern 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) determined from hydrostatic weighing was the criterion measure, and NIR optical density (OD) measurements at multiple sites, plus height, weight, and body mass index (BMI) were the predictor variables.
Results:
Four equations were developed with multiple R2s 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 OD measurements at the biceps, triceps, and thigh sites, BMI, and age. The root 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 % BF among high school wrestlers. Cross-validation of these equations is warranted.
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