Total Error Values Research Articles

Estimating body fat in NCAA Division I female athletes: a five-compartment model validation of laboratory methods

The purpose of the present study was to determine the validity of various laboratory methods for estimating percent body fat (%fat) in NCAA Division I college female athletes (n = 29; 20 +/- 1 year). Body composition was assessed via hydrostatic weighing (HW), air displacement plethysmography (ADP), and dual-energy X-ray absorptiometry (DXA), and estimates of %fat derived using 4-compartment (C), 3C, and 2C models were compared to a criterion 5C model that included bone mineral content, body volume (BV), total body water, and soft tissue mineral. The Wang-4C and the Siri-3C models produced nearly identical values compared to the 5C model (r > 0.99, total error (TE) < 0.40%fat). For the remaining laboratory methods, constant error values (CE) ranged from -0.04%fat (HW-Siri) to -3.71%fat (DXA); r values ranged from 0.89 (ADP-Siri, ADP-Brozek) to 0.93 (DXA); standard error of estimate values ranged from 1.78%fat (DXA) to 2.19%fat (ADP-Siri, ADP-Brozek); and TE values ranged from 2.22%fat (HW-Brozek) to 4.90%fat (DXA). The limits of agreement for DXA (-10.10 to 2.68%fat) were the largest with a significant trend of -0.43 (P < 0.05). With the exception of DXA, all of the equations resulted in acceptable TE values (<3.08%fat). However, the results for individual estimates of %fat using the Brozek equation indicated that the 2C models that derived BV from ADP and HW overestimated (5.38, 3.65%) and underestimated (5.19, 4.88%) %fat, respectively. The acceptable TE values for both HW and ADP suggest that these methods are valid for estimating %fat in college female athletes; however, the Wang-4C and Siri-3C models should be used to identify individual estimates of %fat in this population.

Cross-cultural Validation Of Isokinetic Peak Torque Prediction Equations On Young American Wrestlers

PURPOSE: To determine the validity of fat-free weight equations derived on Saudi children and adolescents for predicting isokinetic peak torque in young American wrestlers. METHODS: One-hundred and eight males (x age ± SD= 11.3 ± 1.5y) volunteered to perform isokinetic leg extensions at 180 and 300°·s−1 on a Cybex II dynamometer to measure isokinetic peak torque (Nm) and underwater weighing to determine fat-free weight (FFW). Predicted peak torque values at 180 and 300°·s−1 were also calculated from FFW using the following formulas: EQ1: Extension Peak Torque at 180°·s−1 = 3.3(FFW) - 54.4 EQ2: Extension Peak Torque at 300°·s−1 = 2.4(FFW) - 38.5 The validity of EQ1 and EQ2 were determined by examining the constant error (CE), r, standard error of estimate (SEE), and total error (TE) values. RESULTS: There were significant (p<0.05) mean differences (CE) between the measured peak torque (x ± SD: 180°·s−1 = 54.9 ± 2.2 Nm; 300°·s−1 = 35.8 ± 1.5 Nm) and predicted peak torque (180°·s−1 = 62.0 ± 3.0 Nm; 300°·s−1 = 46.2 ± 2.2 Nm) at 180 and 300°·s−1. The CE, SEE, and TE values at 180°·s−1 were 7.1, 8.9, and 14.9 Nm, respectively. The CE, SEE, and TE values at 300°·s−1 were 10.4, 6.3, and 14.4 Nm, respectively. In addition, measured peak torque and predicted peak torque were correlated at r = 0.92 for both 180 and 300°·s−1. CONCLUSIONS: Although measured peak torque and predicted peak torque were highly correlated at both 180 and 300°·s−1, the TE values associated with EQ1 and EQ2 ranged from 27 to 40% of the mean measured peak torque values. Thus, EQ1 and EQ2 that were derived on Saudi children and adolescents resulted in error values that were too large to be used to predict isokinetic peak torque in young American wrestlers.

Percent body fat estimations in college men using field and laboratory methods: a three-compartment model approach.

BackgroundMethods used to estimate percent body fat can be classified as a laboratory or field technique. However, the validity of these methods compared to multiple-compartment models has not been fully established. The purpose of this study was to determine the validity of field and laboratory methods for estimating percent fat (%fat) in healthy college-age men compared to the Siri three-compartment model (3C).MethodsThirty-one Caucasian men (22.5 ± 2.7 yrs; 175.6 ± 6.3 cm; 76.4 ± 10.3 kg) had their %fat estimated by bioelectrical impedance analysis (BIA) using the BodyGram™ computer program (BIA-AK) and population-specific equation (BIA-Lohman), near-infrared interactance (NIR) (Futrex® 6100/XL), four circumference-based military equations [Marine Corps (MC), Navy and Air Force (NAF), Army (A), and Friedl], air-displacement plethysmography (BP), and hydrostatic weighing (HW).ResultsAll circumference-based military equations (MC = 4.7% fat, NAF = 5.2% fat, A = 4.7% fat, Friedl = 4.7% fat) along with NIR (NIR = 5.1% fat) produced an unacceptable total error (TE). Both laboratory methods produced acceptable TE values (HW = 2.5% fat; BP = 2.7% fat). The BIA-AK, and BIA-Lohman field methods produced acceptable TE values (2.1% fat). A significant difference was observed for the MC and NAF equations compared to both the 3C model and HW (p < 0.006).ConclusionResults indicate that the BP and HW are valid laboratory methods when compared to the 3C model to estimate %fat in college-age Caucasian men. When the use of a laboratory method is not feasible, BIA-AK, and BIA-Lohman are acceptable field methods to estimate %fat in this population.

Total body water estimations in healthy men and women using bioimpedance spectroscopy: a deuterium oxide comparison

BackgroundTotal body water (TBW) estimations have been used to estimate body composition, particularly fat-free mass, to aid in nutritional interventions, and to monitor hydration status. In the past, bioimpedance spectroscopy (BIS) devices have been used to estimate TBW. Previous investigations have examined the validity of the XiTRON 4000B (XiTRON Technologies) BIS device for estimating TBW. Recently, a new BIS device (Imp™ SFB7) has become available, claiming greater precision when estimating TBW. The Imp™ SFB7 (SFB7) is based on similar BIS principles, while offering increased portability and a greater range of frequencies when compared to older devices, such as the XiTRON 4000B (4000B). The purpose of this study was to examine the validity of the SFB7 for estimating total body water in healthy college-age men and women compared to the 4000B and deuterium oxide (D2O).MethodsTwenty-eight Caucasian men and women (14 men, 14 women; 24 ± 4 yrs; 174.6 ± 8.7 cm; 72.80 ± 17.58 kg) had their TBW estimated by the SFB7, the 4000B, and D2O.ResultsBoth BIS devices produced similar standard error of estimate (SEE) and r values (SFB7, SEE = 2.12L, r = 0.98; 4000B, SEE = 2.99L, r = 0.96) when compared to D2O, though a significant constant error (CE) was detected for the 4000B (2.26L, p ≤ 0.025). The 4000B produced a larger total error (TE) and CE (TE = 3.81L, CE = 2.26L) when compared to the SFB7 (TE = 2.21L, CE = -0.09L). Additionally, the limits of agreement were larger for the 4000B (-3.88 to 8.39L) than the SFB7 (-4.50 to 4.31L). These results were consistent when sex was analyzed separately, though women produced lower SEE and TE values for both devices.ConclusionThe 4000B and SFB7 are valid BIS devices when compared to D2O to estimate TBW in college-age Caucasian men and women. Furthermore, the new SFB7 device displayed greater precision in comparison to the 4000B, which may decrease the error when estimating TBW on an individual basis.

Validity of the BOD POD for Assessing Body Composition in Athletic High School Boys

The purpose of this study was to validate the percentage of body fat (%BF) values estimated from the BOD POD (BP) with those obtained from hydrostatic weighing (HW) in athletic American high school boys. Additionally, the %BF values measured via near-infrared interactance (NIR), bioelectrical impedance (BIA), and skinfold (SF) were compared to HW to determine the validity of these measures. Thirty white boys (mean age +/- SD = 15.8 +/- 1.0 years) who where currently participating in organized sports volunteered to have their %BF estimated. Measurements were obtained from NIR, BP, BIA, and SF in random order and concluded with HW. The findings from the present study indicated that the NIR and BIA instruments produced significant (P < 0.008) constant error (CE) and total error (TE) values that were too large to be of practical value (TE > 4.0%BF). The BP produced a significantly (P < 0.008) higher CE with acceptable TE values compared to HW, but compared to all three SF estimations, the BP TE values were higher. Two of the SF equations were nonsignificant (P > 0.008) and had the lowest TE values compared to HW. These data suggest that the BP can produce acceptable body fat measures for athletic white boys but is not superior to estimates made by the SF equations used in this study.

Establishment of Long-Term Monitoring System for Blood Chemistry Data by the National Health and Nutrition Survey in Japan

We established a monitoring system for the annual follow-up of blood chemistry data obtained by the National Health and Nutrition Survey in Japan. Blood chemistry testing has been entrusted to SRL Inc. We used two external quality control assurance programs established by the Japan Medical Association (JMA) and by CDC/CRMLN during the previous 8-year period. Ten analytes were measured: total cholesterol, HDL cholesterol, triglycerides, urea nitrogen, uric acid, creatinine, AST (GOT), ALT (GPT), gamma-GT (gamma-GTP), and glucose. Total error (TE) was calculated from accuracy by the JMA program and precision by internal quality control of SRL. The permissible range of TE values was determined to be 50% of the evaluation limit on one side in the evaluation criteria of the College of American Pathologists (CAP). When TE fell within the permissible range, the follow-up of annual changes was considered possible. Annual follow-up of blood chemistry data was considered possible for all the analytes except urea nitrogen. Based on this study, new permissible TE ranges are proposed. We confirmed the functioning of the monitoring system for the annual follow-up of blood chemistry data obtained by the National Health and Nutrition Survey in Japan.

Percent body fat estimations in college women using field and laboratory methods: a three-compartment model approach.

BackgroundMethods used to estimate percent body fat can be classified as a laboratory or field technique. However, the validity of these methods compared to multiple-compartment models has not been fully established. This investigation sought to determine the validity of field and laboratory methods for estimating percent fat (%fat) in healthy college-age women compared to the Siri three-compartment model (3C).MethodsThirty Caucasian women (21.1 ± 1.5 yrs; 164.8 ± 4.7 cm; 61.2 ± 6.8 kg) had their %fat estimated by BIA using the BodyGram™ computer program (BIA-AK) and population-specific equation (BIA-Lohman), NIR (Futrex® 6100/XL), a quadratic (SF3JPW) and linear (SF3WB) skinfold equation, air-displacement plethysmography (BP), and hydrostatic weighing (HW).ResultsAll methods produced acceptable total error (TE) values compared to the 3C model. Both laboratory methods produced similar TE values (HW, TE = 2.4%fat; BP, TE = 2.3%fat) when compared to the 3C model, though a significant constant error (CE) was detected for HW (1.5%fat, p ≤ 0.006). The field methods produced acceptable TE values ranging from 1.8 – 3.8 %fat. BIA-AK (TE = 1.8%fat) yielded the lowest TE among the field methods, while BIA-Lohman (TE = 2.1%fat) and NIR (TE = 2.7%fat) produced lower TE values than both skinfold equations (TE > 2.7%fat) compared to the 3C model. Additionally, the SF3JPW %fat estimation equation resulted in a significant CE (2.6%fat, p ≤ 0.007).ConclusionData suggest that the BP and HW are valid laboratory methods when compared to the 3C model to estimate %fat in college-age Caucasian women. When the use of a laboratory method is not feasible, NIR, BIA-AK, BIA-Lohman, SF3JPW, and SF3WB are acceptable field methods to estimate %fat in this population.

Development of a Metabolic Equation for Elliptical Crosstrainer Exercise

The purpose of this study was to develop an accurate metabolic prediction equation for elliptical crosstrainer (ECT) exercise. Male and female (n= 40) subjects (M+/- SD, age: 30+/-7 yr.; height: 173 +/- 11 cm; weight: 72.3 +/- 13.8 kg; body composition: 18.3 +/- 6.9%) completed two randomized testing sessions. Steady-state oxygen uptake (VO2) was measured, while subjects exercised on the ECT at nine separate workloads each testing session. Multiple regression analysis to predict steady-state VO2 from ECT resistance, ECT cadence, and subjects' body mass resulted in the following model (R2= .783): Steady-state VO2=3.5+/-0.15 (Cadence) + 1.22 (Resistance) - 0.11 (Weight). Both the standard error of the estimate (SEE) and total error (TE) for the prediction of steady-state VO2 under all ECT workload conditions combined were 2.8 mL/kg/min. The SEE and TE values are similar to those previously reported in the literature regarding the accuracy of metabolic equations for other exercise modalities. These findings support the use of the equation developed in the present study to predict steady-state VO2 for ECT exercise.

CROSS-VALIDATION OF VENTILATORY THRESHOLD PREDICTION EQUATIONS ON AEROBICALLY TRAINED MEN AND WOMEN

The purpose of this investigation was to determine the validity of the non-exercise-based equations of Davis et al. (13), Jones et al. (20), and Neder et al. (30) for estimating the ventilatory threshold (VT) in samples of aerobically trained men and women. One hundred and forty-four aerobically trained men (mean +/- SD age, 41.0 +/- 11.6 years; N = 83) and women (37.1 +/- 9.0 years, N = 61) performed a maximal incremental test to determine VO2max and observed VT on a cycle ergometer. The observed VT was determined by gas exchange measurements using the V-slope method (VCO2/VO2) in conjunction with analyses of the ventilatory equivalents (i.e., minute ventilation VE/VO2 and VE/VCO2) and end-tidal gas tensions (i.e., P(ET)O2 and P(ET)CO2) for oxygen and carbon dioxide. The predicted VT values from 14 equations were compared to the observed VT values by examining the constant error (CE), standard error of estimate (SEE), Pearson correlation coefficient (r), and total error (TE). The results of this investigation indicated that all 14 equations resulted in significant (p < 0.008) CE values ranging from 1.13 to 1.72 L x min(-1) for the men and from 0.58 to 1.12 L x min(-1) for the women. Furthermore, the SEE, r, and TE values ranged from 0.37 to 0.54, from 0.36 to 0.53, and from 0.68 to 1.81 L x min(-1), respectively. The lowest TE values for the men and women represented 45 and 36% of the mean of the observed VT values, respectively. The results of this study indicated that the errors associated with all 14 equations were too large to be of practical value for estimating VT in aerobically trained men and women.

Validity of VO2max equations for aerobically trained males and females.

The purpose of this investigation was to cross-validate existing VO2max prediction equations on samples of aerobically trained males and females. A total of 142 aerobically trained males (mean +/- SD; 39.0 +/- 11.1 yr, N = 93) and females (39.7 +/- 10.1 yr, N = 49) performed a maximal incremental test to determine actual VO2max on a cycle ergometer. The predicted VO2max values from 18 equations (nine for each gender) were compared with actual VO2max by examining the constant error (CE), standard error of estimate (SEE), correlation coefficient (r), and total error (TE). The results of this investigation indicated that all of the equations resulted in significant (P < 0.006) CE values ranging from -216 to 1415 mL x min(-1) for the males and 132 to 1037 mL x min(-1) for the females. In addition the SEE, r, and TE values ranged from 266 to 609 mL x min(-1), 0.36 to 0.88, and 317 to 1535 mL x min(-1), respectively. Furthermore, the lowest TE values for the males and females represented 10% and 12% of the mean actual VO2max values, respectively. The results of the analysis indicated that the two equations using age, body weight, and the power output achieved at VO2 as predictor variables had the lowest SEE (7.7-9.8% of actual VO2max) and TE (10-12% of actual VO2max) values and are recommended for estimating VO2max in aerobically trained males and females. The magnitude of the TE values (>or= 20% of actual VO2max) associated with the remaining 16 equations, however, were too large to be of practical value for estimating VO2max.

Validity of VO2max Prediction Equations for Aerobically Trained Females

0807 PURPOSE: The purpose of this investigation was to cross-validate existing max prediction equations on a sample of aerobically trained females. METHODS: Fortynine aerobically trained females (mean ± SD; 43.6 ± 7.6 ml/kg/min) performed a maximal incremental test to determine actual max on a cycle ergometer. The predicted max from each of 10 equations was compared to the actual max by examining the constant error (CE), standard error of estimate (SEE), correlation coefficient (r), and total error (TE). RESULTS: The results of this investigation indicated that all of the equations resulted in significant (P< 0.005) CE values ranging from 384 to 1475 ml/min. In addition the SEE, r, and TE values ranged from 149 to 373 ml/min, 0.40 to 0.80, and 564 to 1529 ml/min, respectively. Furthermore, the lowest TE value was 21% of the mean actual max value. CONCLUSION: The results of the analysis indicated that the errors associated with all the equations cross-validated in the present study were too large to be of practical value for estimating max in the female sample. Future studies should use the CE values from the present investigation to adjust the y-intercepts of the prediction equations in the present study and cross-validate the modified equations on an independent sample of aerobically trained females.

Metrological analysis of the LIDFT method

The estimation error components in the DFT linear interpolation (LIDFT) method have been presented in the paper. The equations for random errors, total error, the minimum and optimal parameter value of data window for the case of one complex oscillation, and also the metrological analysis of the multifrequency signal case are presented. This analysis allows us to estimate final method accuracy and obtain the relation for the optimal data window parameter.

THE VALIDITY OF THE TANITA?? BODY FAT MONITOR/SCALE FOR ESTIMATING PERCENT FAT

Recently, Tanita® introduced a commercially available bioelectrical impedance (BIA) device that resembles a bathroom scale and measures both body weight and percent fat (% fat). The scale ranges in cost from $80 – $160 and the manufacturer claims that it is as accurate as more sophisticated body composition techniques, such as underwater weighing (UWW). Therefore, the purpose of the present study was to compare estimates of % fat obtained from the Tanita® scale (TAN) and skinfold (SF) equations (Σ 7 and Σ 3) to values obtained from UWW. Twenty-one inactive males (n = 7) and females (n = 14) (X age ± SD = 26 ± 7 yr, range = 19 - 50 yr, X % fat = 22.5 ± 7.7%, range = 11.8 - 39.7%) volunteered to participate. Body weight (BW) was measured with a calibrated Detecto scale to the mearest 0.11 kg. The SF measurements were taken at the triceps, subscapular, midaxillary, supcailiac, abdomen, chest, and thigh sites. Body density values were calculated using the generalized Σ 7 and Σ 3 SF equations of Jackson and Pollock (Br. J. Nutr. 40:497–504, 1978) and Jackson, Pollock and Ward (MSSE 12:175–182, 1980) for the males and females, respectively. The manufacturer did not supply the BIA equation included with the TAN. Validation analyses included examination of the constant error (CE), correlation (r), standard error of estimate (SEE) and total error (TE): (p < 0.017, Bonferroni corrected alpha 0.05/3 = 0.017)TableThe results indicated that TAN (TE = 5.3 % fat) and SF equations (Σ 7 TE = 4.9 % fat; Σ 3 TE = 5.4 % fat) resulted in TE values that were too large to be of practical value. The results for the SK's are in agreement with others who reported that the technique and these equations have limited applicability to overweight and obese individuals, which represented the majority of subjects in the present study (X % fat ± SD = 19.3 ± 5.0 % and 28.5 ± 6.9 % for the males and females, respectively). Based upon these findings, the TAN and SF techniques are not recommended for estimating % fat in males and females with average to moderately high body fatness.

Regarding the validity of methods of body composition assessment in young and older men and women

To the Editor: In their recent paper, Clasey and coworkers ([3][1]) compared several different methods of estimating body fat. The authors took as their reference method a 4-compartment model involving the measurement of body density, total body water, and total body bone ash ([5][2]). They then

VALIDITY OF BIOELECTRICAL IMPEDANCE EQUATIONS FOR ESTIMATING FAT-FREE WEIGHT IN LEAN FEMALES

The present study examined the validity of bioelectrical impedance (BIA) equations for estimating fat-free weight (FFW) in lean males (X +/- SD = 9.1 +/- 2.2% fat) by comparing the estimates with values obtained from underwater weighing. Sixty-eight Caucasian male volunteers served as subjects. Cross-validation analyses included examination of the constant error (CE), standard error of the estimate (SEE), r, and total error (TE). The results indicated that the equations of Oppliger et al. (16), which resulted in small TE (1.70 kg) and CE (-0.02 kg) values, most accurately estimated FFW. Simple linear regression showed that FFW was more highly correlated with body weight (BW) (r = 0.98, P < 0.0001) and resulted in a lower SEE (1.68 kg) than either height2/resistance (Ht2/R) (r = 0.81, P < 0.0001; SEE = 5.12 kg) or the independent variable (weight x resistance)/height2 [WR/Ht2] utilized by the manufacturer of the BIA analyzer (r = 0.15, P > 0.05; SEE = 8.59 kg). Multiple regression showed that when WR/Ht2, Ht2/R, resistance, body mass index, Ht2, and/or Ht was added to the prediction equation, which utilized BW alone, they accounted for less than 1% additional variance and reduced the SEE by < or = 0.16 kg. The results indicated that BW alone estimated FFW as accurately as any of the BIA equations in lean males.

Validity of Self-Assessment Techniques for Estimating Percent Fat in Men and Women

This study examined the validity of the Accu-Measure™ (AM) and the Futrex 1000 (F-1000) for estimating % body fat (BF) by comparing the estimates to values obtained from skinfold equations (Sum3). Thirty Caucasian men (age 23 ± 3 yrs) and 26 Caucasian women (21 ± 2 yrs) participated in the study. Subjects practiced, then determined their %BF using the AM and the F-1000, while skinfold sites from the Sum3 equations (men = abdomen, chest, thigh; women = triceps, suprailiac, thigh) were measured by an experienced investigator with a Lange caliper. The validity (vs. underwater weighing) for each procedure was determined by examining the constant error (CE), standard error of the estimate, r, and total error (TE). The results were similar for both genders and indicated that the AM, which resulted in the lowest TE values and nonsignificant (p > 0.02) CE values, was as accurate as the Sum3 equations for estimating %BF, and is recommended over the F-1000 for self-assessments of body composition.

Comparison of existing skinfold equations for estimating body fat in African American and white women

The purpose of this study was to compare seven skinfold equations with underwater weighing (UWW) for estimating body fat in 39 African American [age: 22.8 +/- 3.6 y (x +/- SD); weight: 59.6 +/- 8.3 kg) and 39 white (age: 22.1 +/- 2.9 y; weight: 61.7 +/- 7.3 kg) women. The hypothesis examined was that the equations would produce more accurate body fat estimates in white women, but would be appropriate for use in African American women. Body fat estimated from two quadratic, three linear, and two logarithmic skinfold equations was compared with body fat estimated from UWW; the same procedures were used to evaluate the results in both African Americans and whites. The data were analyzed by using t tests, analysis of variance, Scheffé's honestly significant difference tests, correlations, error assessments, and agreement. The results showed that total error, SEE, and SD values were larger in the African American women than in the white women and were not within acceptable limits listed in the literature. The correlation coefficients were lower in the African American women than in the white women. Agreement between the skinfold equations and UWW, based on deviations from mean differences, was better in the white women. In conclusion, the skinfold prediction equations evaluated in this study were more variable and produced more error when used in African American women. Therefore, population-specific equations for African American women should be used to estimate body fat because they will probably yield more accurate estimates.

Reliability and Validity Characteristics of Cardiorespiratory Responses on the StairMaster 4000PT®

The purposes of this study were to determine (a) the test-retest reliability of cardiorespiratory responses to exercise performed on the StairMaster 4000PT® (SM-4000) and (b) the validity of the SM-4000 for estimating oxygen consumption (VO2) based on final SM-4000 stepping speed. Sixty-one participants (30 men, 31 women) performed two graded exercise tests separated by 6 to 8 days. Participants began stepping at the lowest intensity stage (26 steps/min-1) and intensity was increased by 1 stage each minute (8-9 steps/min-1) until volitional exhaustion or until maximal stepping speed was reached (138 steps/min-1). SM-4000-generated VO2 (SMVO2), measured VO2 (MVO2), heart rate, respiratory exchange ratio, and ratings of perceived exertion were measured during each minute of the test. Intraclass (Rxx') and interclass (rxx') reliability coefficients were high for both men and women for all variables (Rxx' ≥ .91 and rxx' ≥ .83 for men, Rxx' ≥ .92 and rxx' ≥ .88 for women). Estimated reliability coefficients from a single administration of the test based on intraclass reliability were high for all variables for both sexes (Rxx' ≥ .83). Standard errors of measurement for SMVO2 and MVO2 indicate these variables are reproducible within small ranges of variation. High concurrent validity coefficients for men and women (rxx' = .87 and .92, respectively) and small Standard Errors of Estimate (2.3 and 2.2 ml middot; kg-1 min-1, respectively), indicate a high correlation exists between SMVO2 and MVO2. However, significant differences between group means for SMVO2 and MVO2 occurred for men (44.3 vs. 37.9 ml · kg-1 · min-1, p < .0001) and women (41.3 vs. 33.2 ml · kg-1 · min -1, p < .0001). This, coupled with large total error values (6.9 and 8.5 ml · kg -1 · min-1 for...

VALIDITY OF DUAL-ENERGY X-RAY ABSORPTIOMETRY FOR ASSESSING CHANGES IN FAT-FREE WEIGHT

828 The present study examined the validity of dual-energy x-ray absorptiometry(DXA) for assessing changes in fat-free weight (FFW) following 8 weeks of weight training by comparing the estimates to values obtained from underwater weighing (UWW). Ten, college-age ([horizontal bar over]X age = 19.0 ± 0.7 yr) football players (n=8 Caucasian; n = 2 Black) served as subjects. FFW from DXA was determined using a Hologic QDR-2000 bone densiometer. Validation analyses pre-training (PRTR) and post-training (POTR) included examination of the constant error (CE), SEE, r value and total error (TE). FFW increased significantly by 3.8 kg following the training period (73.8 to 77.6 kg; p < 0.001). FFW from DXA was not significantly different (p > 0.025) from UWW both PRTR (CE = 0.4 kg) and POTR (CE = 0.3 kg) and resulted in TE values of 2.6 and 2.9 kg, respectively. Correlation analyses indicated that the estimated changes in FFW determined by DXA were moderately correlated with actual changes from UWW (r = 0.46). When evaluating individual data, DXA correctly identified the direction of change in all 10 subjects. However, the magnitude of the change (within 1.0 kg) was only correctly identified in five of the subjects. In summary, DXA was as accurate as UWW for assessing changes in FFW. However, it should be noted that there were differences between the methods for monitoring individual changes in FFW.

Validity of near-infrared interactance for estimating relative body fat in female high school gymnasts.

The present investigation examined the validity of near-infrared interactance (NIR) estimates of relative body fat (% fat) from the Futrex-5000 (F5000), Futrex-5000A (F5000 A), and Futrex-1000 (F1000) instruments. Ninety-eight female high school gymnasts (X age+/-SD = 15.7+/-1.2 yr) participated in this investigation. Subsamples were used to cross-validate the F5000 (n = 52), F5000A (n = 46), and F1000 (n = 89) instruments. The NIR % fat estimates were validated against criterion % fat from underwater weighing (UWW) using the adult conversion constants of Brozek et al. (6) (UWWB) and the female age-specific constants of Lohman (23) (UWWL). The cross-validation statistical analysis included examination of the constant error (CE), standard error of estimate (SEE), r, and total error (TE). In addition, full-model multiple regression analyses were used to predict UWWB or UWWL from body weight (BW) and height (HT). BW and HT were correlated with % fat at R = 0.65-0.70, while the validity coefficients for the NIR instruments ranged from r = 0.40-0.78. The F5000 resulted in nonsignificant CE values (-0.3 % fat vs UWWB and 1.5 % fat vs UWWL; p > 0.008) as well as the lowest TE values (TE = 3.1 % fat vs UWWB and 4.0 % fat vs UWWL). All other NIR estimates of % fat resulted in TE values > or = 6.3 % fat. In addition, for all NIR instruments there were negative correlations for the plots of the CE versus the mean of predicted and criterion (UWWB and UWWL) % fat. Therefore, the present findings indicated that the F5000 provided more accurate estimates of % fat than the F5000A or F1000 instruments, but may underestimate the desired minimal body weight for female gymnasts at the low end of the % fat distribution.