Oxygen Uptake and Plasma Catecholamines During Submaximal and Maximal Exercise After Long-Term β-Receptor Blockade

Abstract

Beta-receptor antagonists lower exercise heart rate and cardiac output, and can thus be expected to interfere with oxygen transport, and hence physical performance, particularly at higher levels of activity. Therefore, the effects of a 4-week and 15-month treatment period with the beta 1-selective receptor blocker acebutolol (500 mg daily) on oxygen uptake and plasma catecholamines during submaximal steady-state and maximal exercise and on maximal work load were studied in eight WHO stage 1 hypertensive men (mean age 36.4 years). Oxygen uptake, ventilation, and plasma noradrenaline, adrenaline, and dopamine concentrations during steady-state exercise were not significantly different from control conditions either after 4 weeks or after 15 months of receptor blockade, although heart rates were significantly (27% and 25%, respectively; P less than 0.01) reduced. After the 4-week treatment period, maximal oxygen uptake (3.9% reduction, NS) and maximal work load (2.4% reduction, NS) tended to be slightly lower after acebutolol compared with control values; maximal oxygen pulse was significantly (P less than 0.05) increased. However, after long-term treatment of 15 months, maximal oxygen uptake was virtually identical compared with pretreatment values, and maximal work load tended to be higher (5.2%, NS); plasma noradrenaline and adrenaline concentrations were significantly (P less than 0.05) enhanced. Since beta 1-selective receptor blockers do not affect maximal oxygen uptake and maximal work capacity after long-term treatment, they appear preferable for patients taking part in preventive and rehabilitative training programs.

Effect of β‐blocking agents with and without intrinsic sympathomimetic activity on work efficiency in healthy men

“…The mechanisms of the improvement of the work efficiency are probably related to several of the multiple metabolic and circulatory effects of &blockade, and no definite conclusions on the mechanism can be drawn from our data. After the intake of j3-blocking drugs the oxygen consumption was reduced at all work loads, which is in harmony with several earlier studies (van Baak, 1988, Kowalchuk & Hughson, 1990), but disagrees with some others (Martin et al, 1989;Franz et al, 1989;Franz et al, 1985). The reduced oxygen consumption rate may be associated with the decreased availability of free fatty acids, due to the inhibition of lipolysis by P-blockers, and the subsequently elevated participation of carbohydrates to energy production, leading to a 10% lower oxygen consumption to produce a certain amount of ATP (van Baak, 1988: Cleroux & Leenen, 1988.…”

Physiologic Responses to Heavy-Resistance Exercise with Very Short Rest Periods*

“…The experimental workout order and type of exercise stations were: (1) the bench press (Olympic barbell), (2) double leg extensions (Nautilus machine), (3) shoulder press (Olympic barbell), (4) double leg curls (Nautilus machine), (5) upright row (Olympic barbell), (6) leg press (Nautilus machine), (7) lat pull down (Universal machine), (8) seated calf raises (calf machine), (9) two-arm curls (barbell), and (10) hang cleans (Olympic barbell). Each exercise was performed for three sets of 10 RM (variable loads) with a 10-s rest between sets.…”

Factors contributing to increased muscle fatigue with β-blockers

“…max following @B (Reybrouck et al 1977;Wilmore et al 1985;SUar et al 1982). Similarly, although some studies suggest that PB significantly reduces oxygen uptake (V%) during submaximal exercise (Pearson et al 1979;Tesch and Kaiser 1983;Anderson et al 1985;Frisk-Holmberg et al 1985), other studies have demonstrated no change (Wilmore et al 1985;Franz et al 1985;Van Hemaarden et al 1979). …”