Thomas S. Altena

Comparison of anthropometry to DXA: a new prediction equation for men

Objective: This study compared three professionally recommended anthropometric body composition prediction equations for men to dual energy X-ray absorptiometry (DXA), and then developed an updated equation, DXA Criterion (DC) from DXA.Design: Cross-sectional.Setting: Exercise Physiology Lab. University of Missouri-Columbia, USA.Subjects: A total of 160 men aged 18–62 y old.Interventions: Percent body fat (%BF) by anthropometry was compared to DXA on the same day.Results: Although %BF was significantly correlated (r=0.923–0.942) (P<0.01) with DXA for all three equations, each equation underestimated %BF (range=3.1–3.3%) (P<0.01) compared to DXA. The following DC equation for men was created: %BF=0.465+0.180(Σ7SF)−0.0002406(Σ7SF)2+0.06619(age); (Σ7SF=sum of chest, midaxillary, triceps, subscapular, abdomen, suprailiac, thigh; age=years). The predicted residual sum of squares (PRESS) R 2 was high (0.90) and the PRESS standard error of estimates was excellent (2.2% at the mean) for the DC equation when applied to our sample of 160 men.Conclusions: The currently recommended anthropometric equations for men underestimate %BF compared to DXA. The DC equation yields a more accurate estimation of %BF in men aged 18–62 y old. The results from this study support the need for the current %BF standards and norms for men to be adjusted upward.

Predicting Postprandial Lipemia in Healthy Adults and in At‐Risk Individuals With Components of the Cardiometabolic Syndrome

To determine whether a single‐point triglyceride (TG) concentration could estimate the 8‐hour postprandial lipemic (PPL) response, men and women performed baseline PPL (n=188) and postexercise PPL (n=92) trials. Correlations were generated between TG concentrations at baseline and at various time points after a high‐fat meal vs 8‐hour area under the TG curve (TG‐AUC) and peak TG level. Stepwise multiple regression and bootstrap simulations using TG level and additional predictor variables of sex, age, percentage of body fat, training status, and maximal oxygen consumption indicated that the 4‐hour TG concentrations accounted for >90% of the variance in TG‐AUC and peak TG responses during the PPL trials. Equations were confirmed by cross‐validation in healthy as well as at‐risk individuals with components of the cardiometabolic syndrome. Our data suggest that the 4‐hour TG value is highly related to the total 8‐hour PPL response and can be used for accurate estimation of PPL in a clinical or research setting.

Skinfold Assessment: Accuracy and Application

Although not perfect, skinfolds (SK), or the measurement of fat under the skin, remains the most popular and practical method available to assess body composition on a large scale (Kuczmarski, Flegal, Campbell, & Johnson, 1994). Even for practitioners who have been using SK for years and are highly proficient at locating the correct anatomical sites and pinching the skin, the question remains—how accurate are the results? Creation of new SK equations using Dual Energy X-Ray Absorptiometry (DXA)technology as the criterion have improved the estimation accuracy achieved by SK. Practitioners are asked to recognize that the equations currently recommended by the American College of Sports Medicine underestimate body fatness by about 3% in both men and women. New equations, developed using DXA as the criterion, are prompting fitness and health professionals to reinterpret the meaning of the percentage of body fat standards for their clients. In summary, the accuracy of various SK assessments are reviewed and various principles of application are presented for the practitioner.