Abstract
The effects of long-term (6 months) antihypertensive treatment with three different
types of beta-blockers (propranolol, nonselective without ISA; pindolol, nonselective
with ISA; metoprolol, beta,-selective without ISA) on submaximal exercise capacity
and metabolic variables during submaximal endurance exercise were studied in seven
subjects with essential hypertension. Exercise tests were performed on a bicycle ergometer
at 70% of estimated V̇O2max.
Similar reductions of resting and exercise blood pressure and exercise heart rate
were obtained with the three beta-blockers. Exercise time was significantly reduced
by all three beta-blockers during chronic antihypertensive therapy. The reduction
tended to be more pronounced after 5-6 months of treatment than after 1 week (P = 0.06). During exercise, the plasma glycerol and nonesterified fatty acid concentrations
were reduced. Plasma glucose concentration was reduced at the end of the exercise
test during propranolol treatment only. Plasma lactate concentrations tended to be
increased, but the difference was significant during pindolol treatment only. Oxygen
uptake tended to decrease and respiratory exchange ratio to increase. Plasma potassium
concentrations during exercise were significantly increased with all three beta-blockers.
The effects on the metabolic variables during exercise were similar after 1 week and
during long-term (20/24 weeks) beta-blocker treatment.
The study shows that submaximal endurance exercise capacity is impaired in patients
with essential hypertension on beta-blocker therapy and that the impairment is maintained
during long-term antihypertensive beta-blocker treatment.
Key words
beta-adrenergic blockade - essential hypertension - submaximal exercise capacity -
chronic treatment - energy metabolism - potassium
