Stephen D. Ball

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.

Comparison of anthropometry to dual energy X-ray absorptiometry: a new prediction equation for women.

Abstract The purpose of this study was to assess the accuracy of three recommended anthropometric equations for women and then develop an updated prediction equation using dual energy x-ray absorptiometry (DXA). The percentage of body fat (%BF) by anthropometry was significantly correlated (r = .896-.929; p < .01) with DXA, but each equation underestimated %BF (3.2-5.6 %BF; p < .01). The following DXA criterion (DC) equation was created: %BF = −6.40665 + 0.41946(S3SF) − 0.00126(S3SF)2 + 0.12515(hip) + 0.06473 (age); (S3SF = sum of triceps, suprailiac, thigh; hip = circumference in cm; age = years). The predicted residual sum of squares (PRESS) R 2 was high (0.86), and the PRESS standard error of estimate (SEE) was low (2.5 %BF) for our sample of 150 women. The DC equation was further crosschecked on a separate sample of women (n = 25) and again showed excellent agreement. The DC equation appears to be a more accurate estimation of %BF in women.

Outcomes of Stay Strong, Stay Healthy in Community Settings:

Loss of muscle strength, flexibility, and balance are strong predictors of falls in the elderly. Objectives: The goal of this research was to investigate the effectiveness of a 10-week, strength-based exercise program delivered by Extension professionals. Methods: Matched pair t tests were used to compare differences in five measures of fitness collected from 808 participants (mean age = 65.4 years) at the start and finish of the exercise program. Results: Following programming, participants significantly improved strength, flexibility, and balance. Discussion: Results indicate that an evidence-based program can be translated into a community Extension program that is able to improve the fitness level of seniors.

Body Composition Comparison: Bioelectric Impedance Analysis with Dual-Energy X-Ray Absorptiometry in Adult Athletes

The primary purpose of this study was to investigate the accuracy of the DF50 (ImpediMed Ltd, Eight Mile Plains, Queensland, Australia) bioelectrical impedance analysis device using dual-energy x-ray absorptiometry as the criterion in two groups: endurance athletes and power athletes. The secondary purpose was to develop accurate body fat percentage prediction equations for each group based on bioelectrical impedance analysis data and/or the combination of bioelectrical impedance analysis and anthropometric data. Eighty male athletes (40 elite endurance athletes and 40 were power athletes), age 19–48 with body mass indexes ranging from 18.9 to 37.4 were recruited. Anthropometric measurements were taken. Body composition was assessed by dual-energy x-ray absorptiometry and bioelectrical impedance analysis. An athlete-specific bioelectrical impedance analysis prediction equation was developed by stepwise regression analysis using dual-energy x-ray absorptiometry as the criterion and bioelectrical impedance analysis data and anthropometric measurements as predictor variables. The DF50 bioelectrical impedance analysis significantly overestimated body fat percentage by 6.4 ± 0.5 in the entire group (p < .001) and in both the endurance group (6.1 ± .6, p < .001) and the power group (6.7 ± 0.7, p < .001). The endurance and power group showed no significant difference in the error of estimation by bioelectrical impedance analysis (p = .554), indicating that bioelectrical impedance analysis has the same error in both groups. The final prediction equation incorporated both anthropometric variables as well as bioelectrical impedance analysis variables and produced an adjusted r2 of .982 and a standard error of the estimate (SEE) of 1.98 for the entire group. This prediction equation used bioelectrical impedance analysis measurements and anthropometric measurements, specifically trunk measurements, to account for trunk size, a common source of error in bioelectrical impedance analysis equations. Follow-up validation studies are necessary to further validate the equations produced.

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.

Effectiveness of Advanced Stay Strong, Stay Healthy in Community Settings

The goal of this research was to investigate the effectiveness of the 10-week, University of Missouri (MU) Extension strength training program Advanced Stay Strong, Stay Healthy (ASSSH). It was hypothesized that the program can improve strength, balance, agility, and flexibility—all physical measures of falling among seniors. Matched pair t tests were used to compare differences in five physical measures of health, body composition, and percent body fat (%BF). Two-way ANOVA was conducted to examine the age effects on changes in physical health from the start and finish of the exercise program. Following programming, participants significantly improved strength, flexibility, and balance, and significantly reduced %BF (p < .05). Our data indicate that ASSSH can improve the physical health of senior citizens and can successfully be translated into community practice by MU Extension professionals.

Validation of a New Skinfold Prediction Equation Based on Dual-Energy X-Ray Absorptiometry

Skinfold prediction equations recommended by the American College of Sports Medicine underestimate body fat percentage. The purpose of this research was to validate an alternative equation for men created from dual energy x-ray absorptiometry. Two hundred ninety-seven males, aged 18–65, completed a skinfold assessment and dual energy x-ray absorptiometry scan to determine percent of body fat. Three American College of Sports Medicine equations (JP7, JP3a, and JP3b) and the new dual energy x-ray absorptiometry criterion equation were used to predict percent of body fat. Mean age was 32.4 ± 14.0 years and mean BMI was 25.6 ± 3.3 kg/m2. The mean dual energy x-ray absorptiometry percent of body fat was 18.0 ± 5.9. The mean percent of body fat for Dual Energy X-Ray Aborptiometry (DC), JP7, JP3a, and JP3b were 19.1 ± 6.3, 16.1 ± 7.4, 14.8 ± 6.8, 15.6 ± 6.7, respectively. The standard error of the estimate of DC was low (2.72%) and was highly correlated (R2 = 0.87) with dual energy x-ray absorptiometry. The DC equation more accurately predicted percent of body fat across a general population of men than the recommended American College of Sports Medicine equations.