Autonomic contribution to heart rate recovery from exercise in humans

Abstract

To assess the contribution of the autonomic nervous system to heart rate recovery following exertion, heart rate was observed after peak treadmill exercise in six men following parasympathetic blockade (PB) with atropine sulfate (0.03 mg/kg), sympathetic blockade (SB) with propranolol hydrochloride (0.20 mg/kg), double blockade (DB) with both drugs, and no drugs (ND). Least-squares analysis of each subject's heart rate (HR) as an exponential function of recovery time (t) was computed for each treatment giving an equation of the form HR = aebt. HRs at rest, peak exercise, and 10 min of recovery, the coefficients a and b, and the least-squares correlation coefficient (r) were compared among treatments by nonparametric analysis of variance and rank-sum multiple comparisons. HR recovered in an exponential manner after dynamic exercise in each subject with each of the treatment modes (P less than 0.01 for each r, mean across all treatments r = 0.94). Coefficients a and b differed the most between PB and SB. At the cessation of exercise the decreases in venous return and the systemic need for cardiac output are accompanied by an exponential HR decline. The exponential character of the cardiodeceleration seen after peak exercise appears to be an intrinsic property of the circulation because it occurred under each experimental condition.

Heart rate variability is related to training load variables in interval running exercises

“…An increase in vagal activation as well as a decrease in sympathetic activation has been detected already during the first minutes of the recovery (Savin et al 1982). It has been suggested that the immediate first minute decline in HR after exercise cessation is mainly vagal in origin (Arai et al 1989;Imai et al 1994;Perini et al 1989;Savin et al 1982), although the relative role of sympathetic and vagal divisions seems to depend on exercise intensity (Imai et al 1994;Perini et al 1989). The recovery of heart rate has widely been investigated in clinical studies, and its prognostic value in different heart diseases has been confirmed.…”

Changes in heart rate recovery index after a programme of strength/endurance training in hypoxia

“…3 This improvement has been associated with various internal physiological adjustments in such a way that a lower heart rate in the recovery phase would be due to decreased venous return and systemic needs. 4 The increase in heart rate in response to exercise is accompanied by a reduction in vagal tone that is further increased over basal level after exercise has ended 5 through the activation of the autonomic nervous system immediately after cessation of maximum activity. 6 In addition to its use to evaluate physical condition, heart rate recovery (HRR) from maximal exercise in the first few minutes after ceasing the activity is also a valid indicator of risk of sudden death during exercise.…”

Heart rate recovery after exercise: relations to heart rate variability and complexity

“…Slower changes in the stimuli to metaboreceptors and baroreceptors accompanying clearance of metabolites and delayed elimination of body heat and catecholamines are thought to be other factors contributing to heart rate recovery after physical activity. Nevertheless, parasympathetic activation is considered to be the main mechanism underlying exponential cardiodeceleration after exercise (1)(2)(3)(4).…”