EFFECT OF ALPHA(1)-ADRENOCEPTOR BLOCKADE ON MAXIMAL VO2 AND ENDURANCECAPACITY IN WELL-TRAINED ATHLETIC HYPERTENSIVE MEN

The effect of alpha(1)-adrenoceptor blockade (doxazosin, 4 mg daily) o n maximal VO2 and physical endurance capacity in 16 mildly hypertensiv e, athletic men was investigated in a randomized, placebo-controlled, double-blind, two-period of 4 weeks, cross-over study. The maximal wor kload obtained during graded bicycle ergometer exercise and the corres ponding maximal VO2 were reduced by 16 +/- 3 W (mean +/- SE), (P = .00 003) and 3 +/- 1 mL/ (kg.min) (P = .0004), respectively, on doxazosin compared with placebo. The running time on a 5000 m track increased by 43 +/- 12 sec on doxazosin (P = .04). Heart rate was unchanged during the running session. Systolic blood pressure was reduced by 9 +/- 4.1 mm Hg (P = .04) immediately after finishing 5000 m. Six subjects repo rted side effects from doxazosin (headache, fatigue, and leg pain). Th us, antihypertensive treatment with alpha(1),selective adrenoceptor bl ockade moderately, but significantly, reduces maximal O-2 consumption and high intensity physical endurance capacity in mildly hypertensive athletic men. Significantly reduced systolic blood pressure and unchan ged heart rate immediately after running, combined with unchanged hear t rate during the race may, however, suggest a safer exercise performa nce.