CAFFEINE INFLUENCES ON EXERCISE AND PSYCHOLOGICAL STRESS

咖啡因的全身作用尚未得到很好的描述， 与人类的生理和心理压力有关。 要么 咖啡因或压力源挑战单独能够影响 心血管功能、神经激素输出和能量动员。 两者结合可能会对这些功能产生影响， 对方的影响。 这个项目的目的是研究咖啡因 改变了这些对心理和身体挑战的反应， 健康的年轻人和那些有发展风险的人 高血压 因此，拟议的研究将检查心理 和身体的挑战结合适度水平的咖啡因， 一对平衡、安慰剂对照、双盲、交叉 对这两个课题组的研究。 心理挑战将是 通过让受试者在高度警惕的状态下工作， 需要脑力劳动来获得金钱奖励。 物理挑战将 包括在分级系列的每一级踩踏自行车测力计 工作量和等长握杆的能力 因变量为： 心血管-心率、全身血压、每搏输出量， 心输出量，收缩末期和舒张末期容积，射血分数， 外周阻力和收缩时间间期;神经内分泌-血浆 去甲肾上腺素、肾上腺素和皮质醇的浓度;以及能量 动员-血浆游离脂肪酸水平和葡萄糖。 的长期 这项工作的目标是建立一个知识基础的作用， 咖啡因可能在调节正常人对压力的生理反应中起作用 以及有患心血管疾病风险的人， 高血压 这些信息将有助于确定 减少咖啡因的使用在预防疾病方面有任何潜力， 对全体人口或某些目标群体， 临界高血压

The systemic effects of caffeine have not been well delineated in conjunction with physical and psychological stress in humans. Either caffeine or stressor challenge alone is capable of influencing cardiovascular function, neurohormonal output, and energy mobilization. The two in combination may interact on these functions, perhaps enhancing each other's effects. The aims of this project are to study how caffeine modifies these responses to psychological and physical challenge both in healthy young men and in those at risk for the development of hypertension. The proposed research will therefore examine psychological and physical challenges in combination with moderate levels of caffeine in a pair of counterbalanced, placebo-controlled, double-blind, corssover studies on these two subject groups. Psychological challenge will be induced by having subjects work under a high state of vigilance on a very demanding mental task to attain monetary reward. Physical challenges will consist of pedalling a bicycle ergometer at each level of a graded series of workloads and isometric handgrip. Dependent variables are: Cardiovascular - heart rate, systemic blood pressures, stroke volume, cardiac output, end-systolic and end-diastolic volumes, ejection fractions, peripheral resistance, and systolic time intervals; Neuroendocrine - plasma concentrations of norepinephrine, epinerphrine, and cortisol; and Energy Mobilization - plasma free fatty acid levels and glucose. The longterm objective of this work is to establish a base of knowledge on the role caffeine may play in modifying physiological responses to stress in nromals and in persons at risk of developing cardiovascular diseases such as hypertension. Such information would be useful in determining whether reduction in caffeine use has any potential in disease prevention either for the population as a whole or for certain targeted groups such as borderline hypertensives.