The effect of acute vs chronic treatment with P–adrenoceptor blockade on exercise performance, haemodynamic and metabolic parameters in healthy men and women

Abstract

1 Variable results have been reported on the effect of P-adrenoceptor blockers on maximal oxygen uptake (Vo, max) and exercise endurance. This may in part be due to different subject populations, but it could also be due to an adaption of metabolic and haemodynamic responses to exercise during chronic treatment with P-adrenoceptor blockers. The present study was therefore carried out to examine the effect of acute and chronic administration of the non-selective P-adrenoceptor blocker propranolol on both peak Vo2 and exercise performance in the same subjects. Since the effect of P-adrenoceptor blockade has not been properly investigated in women, eight healthy women were compared with seven men. Progressive bicycle exercise to exhaustion was performed after propranolol 0.15 mg kg-' i.v. (acute) or 80 mg three times daily for 2 weeks (chronic) or placebo given according to a double-blind crossover design. 2 Mean (s.e. mean) peak Voz, was significantly reduced from 42.3 (1.6)ml min-' kg-' during placebo to 40.3 (1.2, P<O.O5) ml min-l kg-' after acute and 39.1 (1.2, P<O.OOl) ml min-l kg-' after chronic propranolol treatment. No significant difference in peak Vo, between the two propranolol treatment regimens was observed (mean difference 1.2, 95% CI -0.1 to 2.4 ml min-l kg-I). There was no treatment interaction with gender. 3 Cumulative work, 163 (9.3) kJ, was significantly reduced by acute, 148 (7.7, P < 0.001) kJ, and chronic, 147 (7.6, P <0.001) kJ, administration of propranolol since the time to exhaustion was reduced by 5.3% and 5.3%, respectively. There was no significant difference between the two regimens of propranolol (mean difference 0.2, 95% CI -6.7 to 7.0 kJ) or between the sexes. Maximal knee extensor and handgrip strengths were not affected by propranolol. 4 Whereas sex did not influence ventilatory, haemodynamic or metabolic parameters, some differences were observed between acute and chronic propranolol treatment. During submaximal exercise oxygen uptake was reduced by approximately 2% and RER values increased by 0.04-0.05 after chronic treatment in contrast to no effect of acute propranolol treatment. Heart rate and systolic blood pressure were reduced significantly more after chronic compared with acute propranolol treatment; peak heart rate being 186 (2.2), 147 (2.3) and 134 (2.3) beats rnin-l, and peak systolic blood pressure being 189 (7), 171 (4) and 161 (4) mmHg after placebo, acute and chronic propranolol administration, respectively. Also the exercise induced rise in potassium and lactate levels were modified differentially; the rise in potassium concentration was less after chronic compared with acute propranolol treatment and lactate levels were reduced only after chronic administration of propranolol. In contrast, ventilation, which was unchanged after propranolol during submaximal exercise, was reduced to similar extent at exhaustion from 108 (6.4) to 97 (7.2) and 96 (5.9) 1 min-l after acute and chronic propranolol administration, respectively. Diastolic blood pressure and subjective p...

Resting heart rate and physical activity as risk factors for lone atrial fibrillation: a prospective study of 309 540 men and women

“…However, active people might also prefer to avoid the ‘sick role’ and medication. Because flecainide only modestly reduces heart rate and does not affect exercise capacity, it is the preferred drug among physically active AF patients 18. However, using sotalol as the outcome gave similar results.…”

Esmolol acutely alters oxygen supply-demand balance in exercising muscles of healthy humans

“…A widening of the systemic arteriovenous O 2 difference has long been recognized as a compensatory adjustment during exercise in β –blocked humans (Gullestad et al. ; Hughson and Kowalchuk ; MacFarlane et al. ; Tesch ).…”

“…These hemodynamic effects are particularly evident during whole body exercise when compensatory increases in stroke volume are insufficient to preserve cardiac output and when sympathetic outflow increases to active skeletal muscles (Gullestad et al. ; Hughson and Kowalchuk ; MacFarlane et al. ; Tesch ).…”

“…However, these cardiac effects can also reduce the exercise tolerance in people taking these medications due to limitations in systemic O 2 delivery (via an impaired ability to raise heart rate and cardiac output) and active muscle blood flow (via a reduction in local perfusion pressure and/or augmented sympathetic vasoconstriction) (Hughson and Kowalchuk 1991;Pawelczyk et al 1992;Tesch 1985). These hemodynamic effects are particularly evident during whole body exercise when compensatory increases in stroke volume are insufficient to preserve cardiac output and when sympathetic outflow increases to active skeletal muscles (Gullestad et al 1996;Hughson and Kowalchuk 1991;MacFarlane et al 1983;Tesch 1985). For people taking b blockers and performing activities of daily living (e.g.…”

Heart rate recovery improvement in patients following acute myocardial infarction: exercise training, β‐blocker therapy or both

“…Based on the above information, the combination of physical training with b-blocker therapy appears promising for HRR improvement following MI. However, three specific aspects regarding the interaction between physical training and bblocker therapy in terms of HRR improvement need to be further investigated: (i) although b-blockers may facilitate the execution of ET by lowering cardiac work and reducing myocardial O 2 consumption, the adaptations that derive from ET, such as improved total time, O 2 pulse, HR max and VO 2max , appear to become attenuated with the chronic use of this medication (Sable et al, 1982;Wolfel et al, 1986), (ii) The acute effect of b-blocker therapy, compared to chronic use, significantly alters the behaviour of several physiological variables, including resting HR, HR max , Blood pressure (BP), VO 2peak and plasma lactate and potassium levels (Gullestad et al, 1996;Peres et al, 2015). Thus, the presence of b-blockers during HRR evaluation may lead to a result that does not reflect the chronic aspects of the disease, exercise training or long-term b-blocker therapy itself, (iii) Patients initially presenting with an HRR above 12 bpm may show different adaptations compared to patients with a more compromised HRR, because a more normal HRR would reflect intact autonomic function, which consequently may be less affected by ET or b-blocker therapy (Malfatto et al, 2000;Peres et al, 2015).…”