Neder J A, Lerario M C, Castro M L, Sachs A, Nery L E
Centre for Exercise Science and Medicine (CESAME), Institute of Biomedical & Life Sciences (IBLS), University of Glasgow, Glasgow, UK.
Med Sci Sports Exerc. 2001 Nov;33(11):1968-75. doi: 10.1097/00005768-200111000-00025.
Anthropometric (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 VO2 corrected for FFMANTHRO and FFMDEXA, were determined.
Limits of agreement were calculated as mean bias +/- 95% confidence intervals: peak VO2 at maximum cycle ergometry was related to FFMANTHRO and FFMDEXA by using both standard (y x x(-1)) and power function ratios (allometry).
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 x DEXA(-1) x// error ratio): these corresponded to 0.95 x// 1.11 or 0.99 x// 1.15 for total body FFM and 0.90 x// 1.10 or 1.02 x// 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).
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 VO2 values can vary according to the method chosen for body composition assessment, especially when allometry is used for peak VO2 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.
对77名年龄在20 - 80岁之间随机选取的久坐不动的男性和女性进行人体测量学（ANTHRO）和双能X线吸收法（DEXA），以获取全身和腿部的去脂体重（FFM）；确定两种方法间的一致性界限及其临床意义，这是根据经ANTHRO法和DEXA法校正的峰值摄氧量（VO2）差异推断得出的。
一致性界限计算为平均偏差±95%置信区间：使用标准（y×x⁻¹）和幂函数比率（异速生长法），将最大运动负荷时的峰值VO2与ANTHRO法和DEXA法测得的FFM相关联。
ANTHRO - DEXA差异的数据分布在两性中均呈现出显著的异方差性，即差异与均值成比例（P < 0.05）。经对数转换后，平均偏差±95%一致性界限表示为比率（ANTHRO×DEXA⁻¹×误差比率）：全身FFM在男性和女性中分别对应于0.95×1.11或0.99×1.15，腿部FFM分别对应于0.90×1.10或1.02×1.07。此外，我们发现ANTHRO法和DEXA法测得的FFM具有不同的异速生长指数：因此，在幂函数表达后，两种方法间的差异增加（P < 0.05）。
ANTHRO法和DEXA法测量FFM之间的差异取决于估计值的大小：差异通常在10%至15%以内。重要的是，经FFM校正的峰值VO2值会因用于身体成分评估的方法不同而有所变化，尤其是在使用异速生长法进行峰值VO2校正时。这些结果表明，ANTHRO - DEXA在FFM估计上的差异对于分析非训练人群的最大有氧能力确实具有相关的实际影响。
