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Influence of caffeine on metabolic and cardiovascular functions during sustained light intensity cycling and at rest.

机译:咖啡因对持续光强度循环和休息期间对代谢和心血管功能的影响。

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This study assessed the influence of caffeine on metabolic and cardiovascular functions during sustained, light intensity cycling and at rest. Eight healthy, recreationally active adults participated in four randomly assigned, double-blind experimental trials of 60 min upright seated cycle exercise (30% VO2 max) or equivalent rest with caffeine (5 mg.kg-1) or placebo consumed 60 min prior to data collection. Gas exchange was measured by open-circuit spirometry indirect calorimetry. Global blood flow was evaluated by thoracic impedance cardiography and arterial blood pressure by auscultation. A repeated measures ANOVA indicated that pretrial caffeine increased oxygen uptake and energy expenditure rate (p < 0.05) but did not change respiratory exchange ratio. Systolic, diastolic, and mean arterial blood pressure were elevated following caffeine intake (p < 0.05). Cardiac output, heart rate, stroke volume, and systemic vascular resistance were not significantly different between caffeine and placebo sessions. For each of the metabolic and hemodynamic variables examined, the effects of caffeine were similar during constant-load, light intensity cycling and at rest. These data illustrate that caffeine's mild thermogenic influence can be mediated without a major shift in substrate oxidation mixture. Caffeine at this dosage level alters cardiovascular dynamics by augmenting arterial blood pressure.
机译:这项研究评估了咖啡因对持续,轻度循环和休息期间代谢和心血管功能的影响。八名健康,具有娱乐活动能力的成年人参加了四个随机分配的双盲实验试验,这些试验分别是60分钟前进行60分钟的直立坐式自行车运动(最大VO2含量为30%VO2)或咖啡因(5 mg.kg-1)或安慰剂的同等休息时间。数据采集​​。通过开路肺活量测定法间接量热法测量气体交换。通过胸阻抗心动图评估总体血流量,并通过听诊评估动脉血压。重复测量的方差分析表明,庭前咖啡因可增加氧气吸收和能量消耗率(p <0.05),但不会改变呼吸交换率。摄入咖啡因后,收缩压,舒张压和平均动脉血压升高(p <0.05)。咖啡因和安慰剂治疗之间的心输出量,心率,中风量和全身血管阻力无明显差异。对于所检查的每个代谢和血液动力学变量,咖啡因的作用在恒定负荷,光强度循环和静止期间均相似。这些数据表明,咖啡因的温和生热作用可以被介导,而底物氧化混合物不会发生重大变化。此剂量水平的咖啡因可通过增加动脉血压来改变心血管动力学。

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