Cooper Dan M, Leu Szu-Yun, Galassetti Pietro, Radom-Aizik Shlomit
Department of Pediatrics, Pediatric Exercise Research Center, University of California, Irvine, CA.
Med Sci Sports Exerc. 2014;46(5):877-86. doi: 10.1249/MSS.0000000000000180.
Cardiopulmonary exercise testing (CPET) is increasingly used as a biomarker of fitness in children. Maximal or peak values remain the most common variables obtained in CPET, but these physiologically challenging high-intensity work rates (WR) are often not achieved. We hypothesized that interactions of gas exchange, heart rate (HR), and WR CPET variables (slopes) could yield useful mechanistic and clinical insights that might enhance the clinical utility of CPET in children. We further hypothesized that the dependence of the slope on body mass could be predicted by the first-principle analysis of body size and physiological response.
One hundred and sixty-nine healthy participants (8-18 yr old, body mass index <95th percentile, 82 females) underwent dual x-ray absorptiometry scan to estimate lean body mass (LBM) and performed a ramp-type progressive cycle ergometry exercise protocol with a breath-by-breath measurement of gas exchange. Linear regression was used to calculate the slopes among VO2, VCO2, VE, HR, and WR.
ΔWR/ΔHR (r = 0.87) and ΔVO2/ΔHR (r = 0.96) were strongly correlated with VO2peak, whereas ΔVO2/ΔWR (r = 0.42) and ΔVE/ΔVCO2 (r = -0.51) were mildly correlated with peak values. LBM was more highly correlated with those slopes predicted to be body size dependent (P < 0.0001) compared with total body mass.
The data largely supported our original hypotheses. Unlike peak or maximal values, which are derived from no more than a few data points at the end of a progressive exercise test, the CPET slopes were calculated from a much larger data set obtained throughout the test. An analysis of these slopes might ultimately prove useful clinically and in research studies when peak values are not achieved.
心肺运动试验（CPET）越来越多地被用作儿童体能的生物标志物。最大值或峰值仍然是CPET中最常获得的变量，但这些在生理上具有挑战性的高强度工作率（WR）往往无法达到。我们假设气体交换、心率（HR）和WR CPET变量（斜率）之间的相互作用可以产生有用的机制和临床见解，这可能会提高CPET在儿童中的临床应用价值。我们进一步假设，可以通过对身体大小和生理反应的第一性原理分析来预测斜率对体重的依赖性。
169名健康参与者（8 - 18岁，体重指数<第95百分位数，82名女性）接受双能X线吸收法扫描以估计瘦体重（LBM），并进行斜坡式递增功率自行车运动试验，同时逐次呼吸测量气体交换。使用线性回归计算VO₂、VCO₂、VE、HR和WR之间的斜率。
ΔWR/ΔHR（r = 0.87）和ΔVO₂/ΔHR（r = 0.96）与VO₂峰值密切相关，而ΔVO₂/ΔWR（r = 0.42）和ΔVE/ΔVCO₂（r = -0.51）与峰值轻度相关。与总体重相比，LBM与那些预计依赖于身体大小的斜率相关性更高（P < 0.0001）。
数据在很大程度上支持了我们最初的假设。与在递增运动试验结束时仅从几个数据点得出的峰值或最大值不同，CPET斜率是根据整个试验中获得的大得多的数据集计算得出的。当未达到峰值时，对这些斜率的分析最终可能在临床和研究中证明是有用的。
