Peak VO2 correction for fat-free mass estimated by anthropometry and DEXA
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2001-11-01
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Neder, José Alberto [UNIFESP]
Lerario, Maria Cristina [UNIFESP]
Lazaretti-Castro, Marise [UNIFESP]
Sachs, Anita [UNIFESP]
Nery, Luiz Eduardo [UNIFESP]
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Purpose: Anthopometric (ANTHRO) and dual-energy x-ray absorptiometric (DEXA) estimates of total body and leg fat-free masses (FFM) were obtained in 77 randomly selected sedentary men and women, aged 20-80: intermethod limits of agreement and their clinical significance, as inferred from the differences on peak (V)over dotO(2) corrected for FFMANTHRO and FFMDEXA, were determined. Methods: Limits of agreement were calculated as mean bias +/- 95% confidence intervals: peak (V)over dotO(2) at maximum cycle ergometry was related to FFM(ANTHRO)and FFMDEXA by using both standard (y.x(-1)) and power function ratios (allometry). Results: Data distribution of the ANTHRO-DEXA differences presented significant heteroscedasticity in both sexes, i.e., differences were proportional to the mean (P<0.05). After logarithmic transformation, the mean bias 95% limits of agreement were expressed as ratios (ANTHRO-DEXA(-1) x/<divided by> error ratio): these corresponded to 0.95 x/divided by 1.11 or 0.99 x/divided by 1.15 for total body FFM and 0.90 x/divided by 1.10 or 1.02 x/divided by 1.07 for leg FFM in men and women, respectively. in addition, we found different allometric exponents for FFMANTHRO and FFMDEXA: the intermethod differences, therefore, increased after power function expression (P<0.05). Conclusion: Discrepancies between ANTHRO and DEXA measurements of FFM depend on the magnitude of the estimate: differences are typically within 10 to 15%. Importantly, FFM-corrected peak (V)over dotO(2) values can vary according to the method chosen for body composition assessment, especially when allometry is used for peak (V)over dotO(2) correction. These results demonstrate that ANTHRO-DEXA differences in FFM estimation do have relevant practical consequences for the analysis of maximum aerobic capacity in nontrained humans.
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Medicine and Science in Sports and Exercise. Philadelphia: Lippincott Williams & Wilkins, v. 33, n. 11, p. 1968-1975, 2001.