Carotid–cardiac baroreflex and training status: significance of initial responsiveness
- 1 January 1995
- journal article
- clinical trial
- Published by Canadian Science Publishing in Canadian Journal of Physiology and Pharmacology
- Vol. 73 (1), 98-106
- https://doi.org/10.1139/y95-014
Abstract
The aim of this study was to demonstrate that within a population of healthy men (n = 15) of varying levels of aerobic fitness [Formula: see text], (i) there are high and low responders with respect to carotid–cardiac baroreflex responsiveness, despite similar baseline heart rates (HRs) both at rest and during dynamic exercise, and (ii) there is a weak association between this responsiveness and training status [Formula: see text] because of a large overlap in the responses between trained (endurance, ET) and untrained (UT) individuals. Baroreflex function curves were derived during supine rest for each subject by applying varying pressures around the neck in a beat-to-beat ramp (for 12 beats) of +40 to −60 mmHg (1 mmHg = 133.3 Pa). Subjects were divided into low (n = 8) and high (n = 7) responders on the basis of the magnitude of the maximal dynamic R–R interval (RRI) range of the baroreflex curve. Both bradycardic (percent slowing) and tachycardic (percent acceleration) components of the baroreflex curve, and peak sinus node responses (HR, RRI) to continuous neck suction (−60 mmHg) at rest and during exercise (cycling, 45% [Formula: see text]) were greater in high compared with low responders (p < 0.05), as assessed using both HR and RRI scales. When subjects were divided into ET and UT groups, both RRI range and maximal gain at rest were the only indices of baroreflex responsiveness that were different (p < 0.05) between the two groups, and a significant correlation was found between [Formula: see text] and RRI range (r2 = 0.497, p < 0.01); a lower resting HR in ET and mathematical skewing with the RRI scale could in part explain these findings. Taken together, these results emphasize that initial carotid–cardiac baroreflex responsiveness must be considered when assessing the effect of exercise training on baroreflex function.Key words: arterial baroreflex, bradycardia, parasympathetic, endurance training.Keywords
This publication has 15 references indexed in Scilit:
- Unilateral carotid-cardiac baroreflex responses in exercise trained and untrained menMedicine & Science in Sports & Exercise, 1994
- Cardiopulmonary receptor reflexes in normotensive athletes with cardiac hypertrophy.Circulation, 1990
- 627 EFFECT OF CHRONIC ENDURANCE TRAINING ON REFLEX CONTROL OF BLOOD PRESSURE IN HUMANSMedicine & Science in Sports & Exercise, 1990
- Influence of physical training on heart rate variability and baroreflex circulatory controlJournal of Applied Physiology, 1989
- Autonomic mechanisms and sudden death. New insights from analysis of baroreceptor reflexes in conscious dogs with and without a myocardial infarction.Circulation, 1988
- Vagal and sympathetic components of the heart rate range and gain of the baroreceptor-heart rate reflex in conscious ratsJournal of the Autonomic Nervous System, 1987
- Parasympathetic control of resting heart rate: relationship to aerobic powerMedicine & Science in Sports & Exercise, 1985
- Vagal stimulation and cardiac slowingJournal of the Autonomic Nervous System, 1984
- Phase relationship between normal human respiration and baroreflex responsiveness.The Journal of Physiology, 1980
- 'Steady-state' properties of the baroreceptor-heart rate reflex in essential hypertension in manClinical and Experimental Pharmacology and Physiology, 1974