Sport Modality Affects Bradycardia Level and Its Mechanisms of Control in Professional Athletes

Abstract

We investigated the influence of sport modalities in resting bradycardia and its mechanisms of control in highly trained athletes. In addition, the relationships between bradycardia mechanisms and cardiac structural adaptations were tested. Professional male athletes (13 runners, 11 cyclists) were evaluated. Heart rate (HR) was recorded at rest on beat-to-beat basis (ECG). Selective pharmacological blockade was performed with atropine and esmolol. Vagal effect, intrinsic heart rate (IHR), parasympathetic (n) and sympathetic (m) modulations, autonomic influence (AI) and autonomic balance (Abal) were calculated. Plasmatic norepinephrine (high-pressure liquid chromatography) and cardiac structural adaptations (echocardiography) were evaluated. Runners presented lower resting HR, higher vagal effect, parasympathetic modulation (n), AI and IHR than cyclists (P<0.05). Abal, sympathetic modulation (m) and norepinephrine level were similar within athletes regardless of modality. The cardiac chambers were also similar between runners and cyclists (P=0.30). However, cyclists displayed higher septum and posterior wall thickness than runners (P=0.04). Further analysis showed a trend towards inverse correlation between IHR with septum wall thickness and posterior wall thickness (P=0.056). Type of sport influences the resting bradycardia level and its mechanisms of control in professional athletes. Resting bradycardia in runners is mainly dependent on an autonomic mechanism. In contrast, a cyclist's resting bradycardia relies on a non-autonomic mechanism probably associated with combined eccentric and concentric hypertrophy.

Irisin evokes bradycardia by activating cardiac-projecting neurons of nucleus ambiguus

“…; Azevedo et al. ). Since irisin is secreted by muscle and adipose tissue during exercise (Bostrom et al.…”

“…The type and intensity of exercise determine the level of resting bradycardia and its mechanisms of control (Azevedo et al. ). The current study examined the effect of irisin on cardiac‐projecting neurons of nucleus ambiguus, a critical site for central parasympathetic cardiac control (Mendelowitz ).…”

Heart Rate Variability and Body Composition as Vo2max Determinants

“…In addition, due to the use of digital signal processing systems, this TS can be analyzed by characteristics of its spectrum and by nonlinear methods 6 . Similarly, both HRV and heart rate (HR) at rest account for cardiovascular adaptations such as left ventricular hypertrophy and increased parasympathetic tone 7 .…”

Fatiguing exercise initiated later in life reduces incidence of fibrillation and improves sleep quality in Drosophila

“…After that, we explored the effect of distinct doses of physical exercise training initiated in 4-week-old flies on the cardiac dynamic aspect. We found that 2 or 2.5 h of exercise training per day for five weekly endurance exercise sessions over 2 weeks reduced the resting heart rate, which was manifested in an Bathlete's heart,^also named exercise bradycardia, which provides more cardiac reserve (Lewis et al 1980;Azevedo et al 2014;Heinonen et al 2014) when the individual is suffering from cardiac stress. The decreased heart rate was due to 271.67 ± 40.14 the increasing diastolic interval, which may be beneficial to heart filling.…”