title: Caffeine elevates blood pressure response to exercise in mild hypertensive men.
abstract: The present study examined the effects of caffeine on blood pressure (BP) regulation in hypertensive men during exercise. Twenty unmedicated, mild hypertensives (HT, BP = 140/90 to 160/105 mm Hg) and 12 age-matched, normotensives (NT, BP < 130/80 mm Hg) performed 30 min of extended bicycle exercise following a single dose of caffeine (3.3 mg/kg, equivalent to 2 to 3 cups of coffee) and placebo in a double-blind, cross-over design. Hemodynamic measurements were made at predrug, 40-min postdrug and during exercise. At predrug baseline, HT had significantly higher HR (67 v 57 beats/min) and BP (141/96 v 118/72 mm Hg) than NT. At postdrug baseline, caffeine increased systolic and diastolic BP, and peripheral vascular resistance (P < .01 in all cases), decreased HR (P < .05) and did not significantly change stroke volume and cardiac output for both groups. During exercise, HR response was greater on caffeine day than placebo day in HT (P < 0.05) only. Systolic BP was consistently elevated on caffeine day compared to placebo day in both groups (P < .001). Diastolic BP was elevated in HT for 30 min of exercise on caffeine day, but this pressor effect disappeared at 15 min of exercise in NT. As a result, rate-pressure products were significantly higher on caffeine days in HT at postdrug and during exercise. On caffeine day, 7 (39%) HT and 1 (8%) NT showed an excessive BP response (> 230 for systolic or > 120 for diastolic) during exercise. In conclusion, caffeine has significant hemodynamic effects on mild hypertensives at rest and during exercise. The increased rate-pressure products following caffeine during exercise place a greater workload on the heart, and abstinence from caffeine, especially before exercise, may be beneficial for persons with hypertension.
authors.affiliation: Department of Medicine, State University of New York, Buffalo 14209, USA.
authors.forename: B H
authors.initials: BH
authors.lastname: Sung
authors.forename: W R
authors.initials: WR
authors.lastname: Lovallo
authors.forename: T
authors.initials: T
authors.lastname: Whitsett
authors.forename: M F
authors.initials: MF
authors.lastname: Wilson
mesh_terms: D000328:Adult; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology*; D002110:Caffeine / Q000493:pharmacokinetics / Q000494:pharmacology*; D000697:Central Nervous System Stimulants / Q000493:pharmacokinetics / Q000494:pharmacology*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D004562:Electrocardiography / Q000187:drug effects; D015444:Exercise / Q000502:physiology*; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D006973:Hypertension / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged
chemical_list: D000697:Central Nervous System Stimulants; D002110:Caffeine