Saynor Zoe Louise, Barker Alan Robert, Oades Patrick John, Williams Craig Anthony
1Children's Health and Exercise Research Centre, Sport and Health Sciences, University of Exeter, Exeter, Devon, UNITED KINGDOM; and 2Paediatric Unit, Royal Devon and Exeter NHS Foundation Trust, Exeter, Devon, UNITED KINGDOM.
Med Sci Sports Exerc. 2016 Nov;48(11):2090-2099. doi: 10.1249/MSS.0000000000001004.
This study aimed to investigate the effects of mild-to-moderate cystic fibrosis (CF) on the pulmonary oxygen uptake (V˙O2) kinetics of seven pediatric patients (13.5 ± 2.8 yr) versus seven healthy matched controls (CON; 13.6 ± 2.4 yr). We hypothesized that CF would slow the V˙O2 kinetic response at the onset of moderate (MOD) and very heavy (VH) intensity cycling.
Changes in breath-by-breath V˙O2, near-infrared spectroscopy-derived muscle deoxygenation ([HHb]) at the vastus lateralis muscle and thoracic bioelectrical impedance-derived heart rate (HR), stroke volume index, and cardiac index were measured during repeat transitions to MOD (90% of the gas exchange threshold) and VH (Δ60%) intensity cycling exercise.
During MOD, the phase II V˙O2 τ (P = 0.84, effect size [ES] = 0.11) and the overall mean response time (MRT) (P = 0.52, ES = 0.11) were not significantly slower in CF versus CON. However, during VH exercise, the phase II V˙O2 τ (P = 0.02, ES = 1.28) and MRT (P = 0.01, ES = 1.40) were significantly slower in CF. Cardiac function, central O2 delivery (stroke volume index and cardiac index), and muscle [HHb] kinetics were unaltered in CF. However, the arteriovenous O2 content difference ((Equation is included in full-text article.)) was reduced during VH at 30 s (P = 0.03, ES = 0.37), with a trend for reduced levels at 0 s (P = 0.07, ES = 0.25), 60 s (P = 0.05, ES = 0.28), and 120 s (P = 0.07, ES = 0.25) in CF. Furthermore, (Equation is included in full-text article.)significantly correlated with the VH phase II V˙O2 τ (r = -0.85, P = 0.02) and MRT (r = -0.79, P = 0.03) in CF only.
Impairments in muscle oxidative metabolism during constant work rate exercise are intensity dependent in young people with mild-to-moderate CF. Specifically, V˙O2 kinetics are slowed during VH but not MOD cycling and appear to be mechanistically linked to impaired muscle O2 extraction and utilization.
本研究旨在调查轻度至中度囊性纤维化（CF）对7名儿科患者（13.5±2.8岁）与7名健康匹配对照者（CON；13.6±2.4岁）肺氧摄取（V˙O2）动力学的影响。我们假设CF会减缓中度（MOD）和极重度（VH）强度骑行开始时的V˙O2动力学反应。
在重复进行到MOD（气体交换阈值的90%）和VH（Δ60%）强度的骑行运动过程中，测量逐次呼吸的V˙O2变化、股外侧肌近红外光谱法测定的肌肉去氧血红蛋白含量（[HHb]）以及胸部生物电阻抗法测定的心率（HR）、每搏量指数和心脏指数。
在MOD期间，CF组与CON组相比，II期V˙O2时间常数（P = 0.84，效应量[ES] = 0.11）和总体平均反应时间（MRT）（P = 0.52，ES = 0.11）并无显著减慢。然而，在VH运动期间，CF组的II期V˙O2时间常数（P = 0.02，ES = 1.28）和MRT（P = 0.01，ES = 1.40）显著减慢。CF组的心脏功能、中心氧输送（每搏量指数和心脏指数）以及肌肉[HHb]动力学未发生改变。然而，在VH运动30秒时，CF组的动静脉氧含量差（（全文包含公式。））降低（P = 0.03，ES = 0.37），在0秒（P = 0.07，ES = 0.25）、60秒（P = 0.05，ES = 0.28）和120秒（P = 0.07，ES = 0.
