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

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 cardio-selective 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 W vs. 269.0±41.5 W; lactate: 8.7±2.6mmol/l vs. 8.6±3.2mmol/l and VO2max: 3110±482ml/min vs. 3077±425ml/min, respectively; p=ns). Epinephrine and norepinephrine showed a similar exponential increase to maximum load with and without beta blockade (epinephrine max 1.92±1.8 nmol/l vs. 1.93±1.3; p=ns; norepinephrine max 12.78±7.9 nmol/l vs. 16.89±12.2; p=ns). Beta-blockade lowered heart rate (HR) and systolic blood pressure (SBP) at rest and under maximum load (ΔHR rest: 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.