The effect of a week's beta‐adrenoceptor antagonism on daytime heart‐ rates, subjective responses to exercise, and physical activity in normal subjects.

Abstract

1 The effects on heart rate (HR) and physical activity of 1 week's treatment with three different ,-adrenoceptor antagonists (20 mg betaxolol (Lorex); 160 mg propranolol LA; or 100 mg atenolol daily) have been compared with placebo in a double-blind study of 12 normal men. 2 On the fifth day of each treatment a body-borne tape-recorder was worn during waking hours for recording of ECG and footfall signals. Each record was calibrated in terms of the subject's response to laboratory ergometer exercise, and a computer analysis provided objective indices of physical activity. 3 While on ,-adrenoceptor antagonists the subjects perceived standard exercise as significantly harder than on placebo lnd reported more side-effects (albeit mild and transient). 4 Ambulatory monitoring of HR showed that subjects spent 13% of their waking day at heart rates below 50 beats min-' while on propranolol, compared with 1% on placebo and 20% on atenolol and betaxolol. On these latter drugs, the group spent as much as 10% of their waking time with HR below 45 beats min-1. The lowest individual heartrates recorded were below 35 beats min-. 5 Objective indices of physical activity, such as the duration of periods spent with heart rates above the HR found at 100 W in the ergometer test, showed no differences between the treatments. This negative finding was confirmed by pedometer step counts over the whole week.

The comparative effects of ICI 118551 and propranolol on essential tremor.

“…The well-reported cardiovascular effects of 1B-adrenoceptor blockers including hypotension, bradycardia and reduced exercise tolerance (Pearson et al, 1979;Twentyman et al, 1981;Patrick et al, 1985) may be unacceptable. However ICI 118551 had no significant effect on supine and standing blood pressures and resting heart rate and a relatively small effect compared with propranolol on exercise tachycardia.…”

“…There is evidence that the effect on tremor is mediated in part by mechanisms involving 12-adrenoceptors (Marsden et al, 1967;Dietrichson & Espen, 1981;Leigh et al, 1983;Findley & Cleeves, 1984). Since the effects of non-selective 13-adrenoceptor antagonists cannot be confined to those which are beneficial for tremor, some unwanted effects may arise such as bradycardia, hypotension and reduced exercise tolerance (Twentyman et al, 1981;Patrick et al, 1985).…”

Objective Measurements of Customary Physical Activity in Elderly Men and Women Before and After Retirement

“…min-m to allow for day-to-day variation) was also us,:I to provide the reference heart rate for assessment of the intensity of activity in the 24 h tape-recordings. This calibration procedure is necessary because there is wide variation in heart rate between individuals at a given activity due to variations in body fat, fat-free mass, age and customary activity level (3assey et al 1982), and sometimes due to the effects of prescribed drugs like ,3-adrenoceptor antagconists (Patrick, Wharrad, Wilson & Birmingham, 1985).…”