The possible combined effects of caffeine and exercise on blood pressure (BP) regulation were examined in 34 healthy, normotensive (BP less than 135/85 mm Hg) young men (mean age 27 +/- 3 years) in a placebo-controlled, double-blind crossover design. Each subject performed submaximal and symptom-limited maximal supine bicycle exercise 1 hour apart after ingestion of placebo or caffeine (3.3 mg/kg). Heart rate, BP, cardiac output and peripheral vascular resistance were compared for placebo and caffeine days. Postdrug baseline showed that caffeine increased systolic and diastolic BP and peripheral vascular resistance (p less than 0.001 for each) and decreased heart rate (p less than 0.01) but did not change stroke volume or cardiac output. BP and vascular resistance effects of caffeine remained during submaximal exercise resulting in an additive increase in BP while negative chronotropic effects of caffeine disappeared. At maximal exercise substantially more subjects (15 on caffeine vs 7 on placebo, p less than 0.02) had systolic BP greater than or equal to 230 mm Hg and/or greater than or equal to 100 mm Hg for diastolic BP. Plasma norepinephrine levels were not significantly different across days, but epinephrine was higher at maximal exercise and cortisol was increased post-drug and throughout maximal exercise on caffeine days. Data indicate that caffeine increases BP additively during submaximal exercise and may cause excessive BP responses at maximal exercise for some individuals. The pressor effects of caffeine appear to be due to increasing vascular resistance rather than cardiac output.

译文

在安慰剂对照中,在34名健康,血压正常 (血压低于135/85mm Hg) 的年轻男性 (平均年龄27/- 3岁) 中检查了咖啡因和运动对血压 (BP) 调节的可能综合作用,双盲交叉设计。每个受试者在摄入安慰剂或咖啡因 (3.3 mg/kg) 后1小时间隔进行次最大和症状受限的最大仰卧自行车运动。比较安慰剂和咖啡因天数的心率,血压,心输出量和外周血管阻力。药物后基线显示,咖啡因增加收缩压和舒张压以及周围血管阻力 (每个p小于0.001) 和降低心率 (p小于0.01),但不改变中风量或心输出量。在次最大运动期间,咖啡因的BP和血管阻力效应仍然存在,导致BP的累加性增加,而咖啡因的负变时性效应消失了。在最大运动时,明显更多的受试者 (咖啡因组15例,安慰剂组7例,p小于0.02) 的收缩压大于或等于230毫米Hg和/或舒张压大于或等于100毫米Hg。血浆去甲肾上腺素水平在不同的日子没有显着差异,但肾上腺素在最大运动时较高,皮质醇在服药后和咖啡因的整个最大运动中增加。数据表明,咖啡因在次最大运动期间会增加BP,并可能导致某些人在最大运动时产生过多的BP反应。咖啡因的升压作用似乎是由于血管阻力增加而不是心输出量增加所致。

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