Caffeine Attenuates Early Post-Exercise Hypotension in Middle-Aged Subjects

Background Sustained hypotension after an acute dynamic exercise bout is due primarily to peripheral vasodilation. We tested the hypothesis that adenosine-mediated vasodilation contributes to hypotension after exercise, by determining the effect of blocking its actions with caffeine. Methods Fourteen healthy middle-aged subjects (mean age = 51 ± 3 years), cycled to peak effort on 2 study days, after a randomized double-blind intravenous infusion of caffeine (4 mg/kg) selective for adenosine receptor blockade, or vehicle. Both studies were performed after 72 h of caffeine abstinence. Results Infusion achieved 52.0 ± 6.1 μmol/L caffeine in plasma. Significant reductions in mean and diastolic blood pressure (BP) were elicited by prior exercise on the vehicle day (from 93 ± 2 to 85 ± 2 mm Hg v from 79 ± 2 to 73 ± 3 mm Hg, respectively; both P< .05), but not after caffeine infusion. Systolic and mean BP, 10 min after exercise, were higher on the caffeine than on the vehicle day (by 9 ± 3 and 6 ± 2 mm Hg, respectively; P< .05), as was heart rate (HR) (100 ± 5 v 93 ± 4 beats/min; P< .05). Conclusions These data suggest that endogenous adenosine contributes to early hypotension after exercise in healthy middle-aged subjects and underscore the importance of caffeine abstinence if BP or HR immediately after exercise is used to infer cardiovascular risk.