Effects of cardioselective beta-blockade on plasma catecholamines and performance during different forms of exercise.

ABSTRACT

BACKGROUND: Beta-blockers are still frequently used in cardiovascular diseases but may negatively influence the exercise capacity. The aim of the study was to analyze the effect of beta-blockade on physical performance and plasma level of catecholamine during different forms of exercise. METHODS: Ten prehypertensive athletes (age 25.1±2.5 years, BMI 24.4±2.4 kg/m2) performed repeated incremental exercise and steady-state-tests without and with the cardioselective beta-blocker bisoprolol (5mg/day). The cardiopulmonary, metabolic and the catecholamine responses were monitored. RESULTS: Beta-blocker treatment had no effect on maximum power output (Pmax), lactate and the maximal oxygen uptake (VO2max) (Pmax 269.0±41.5 vs. 269.0±41.5 W; lactate 8.7±2.6 vs. 8.6±3.2 mmol/L and VO2max 3110±482 vs. 3077±425 mL/min, respectively; P not significant). Epinephrine and norepinephrine showed a similar exponential increase to maximum load with and without beta-blockade (epinephrinemax 1.92±1.8 vs. 1.93±1.3 nmol/L; P not significant; norepinephrinemax 12.78±7.9 vs. 16.89±12.2 nmol/L; P not significant). Beta-blockade lowered heart rate (HR) and systolic blood pressure (SBP) at rest and under maximum load (ΔHRrest 10.6±11.1 bpm, P<0.05, ΔHR-Max 27.8±6.6 bpm, P<0.01; ΔSBPrest 19.4±9.3 mmHg, P<0.05, ΔSBPmax 17.7±15.3 mmHg, P<0.01). The maximum oxygen pulse was higher in the tests performed under beta-blockade (IET ΔVO2/HR 3.1±2.2 mL/beat, P<0.01; SST ΔVO2/HR 3.4±1.4 mL/beat, P<0.001). CONCLUSIONS: Despite beta blockade and resulting differences in cardiopulmonary regulation during the exercise tests, the maximal oxygen capacity and the catecholamine concentration was similar. Higher exercise intensities (>50% Pmax) are associated with a marked increase in plasma catecholamines, which are not influenced by treatment with bisoprolol 5 mg/day.