Autonomic Modulation Of Heart Rate Variability Research Articles

Post-exercise heart rate recovery and its speed are associated with cardiac autonomic responsiveness following orthostatic stress test in men

Objective: The present study sought to expand upon prior investigations of the relationship between the post-exercise heart rate recovery (HRR) and the cardiac autonomic responsiveness after orthostatic stress test. Method: HRR at the 1st, 3rd, and 5th min after maximal exercise test were correlated with relative change (Δ%) of time-domain (CV, pNN50, and rMSSD) and frequency-domain (TP, LF, HF, and LF/HF ratio) indices of heart rate variability (HRV) after active orthostatic test in 46 healthy men. Statistical analysis employed non-parametric tests with a p-value set at 5%. Results: HRR at 1st min correlated with Δ%pNN50 (rs:0.36 – p = .02). In the 3rd and 5th min, these measures correlated with Δ%pNN50, Δ%rMSSD, Δ%CV, Δ%TP, and Δ%HF indices (rs:0.33, 0.59 – p ≤ .05). Coefficient of HRR at the 1st min correlated with Δ%pNN50, Δ%rMSSD, and Δ%HF (rs:0.28, 0.45 – p ≤ .05). The 3rd and 5th min showed correlation with Δ%pNN50, Δ%rMSSD, Δ%HF, Δ%CV, and Δ%TP (rs:0.37, 0.64 – p ≤ .05). No correlation was found with indices combined sympathetic-parasympathetic modulation and HRR. After the sample was divided into high and low parasympathetic responsiveness subgroups after the orthostatic test, faster HRR was associated with the degree of parasympathetic responsiveness (reduction) following postural change (p ≤ .05). Conclusion: HRR throughout the 1st to 5th min is positively correlated with parasympathetic responsiveness and overall cardiac autonomic modulation of HRV after the orthostatic stress test, and faster HRR is positively correlated with the relative degree of parasympathetic responsiveness after the active postural change at rest in healthy men.

Study of Heart Rate Variability and Stress Markers in Basketball Players Submitted to Selective Loads Periodization System

The decrease in the performance of athlete is often associated with an imbalance between workload and recovery period. Thus, it is very important to implement tools which can assist in the quantifying the effects of workloads, so that the maximum performance of the athlete is reached. In this context, we know little about the influence of selective load periodization system (SLPS) on cardiac autonomic control and the effects on stress markers already known. Thus, the aim of this study was to investigate if the application of SLPS promoted alterations in autonomic modulation of heart rate variability (HRV), as well as same stress markers. Therefore, sixteen male basketball players (mean ± SE: age 23.3 ± 1.0 years; mass 87.5 ± 3.5 kg; height 194  2 cm) were submitted to SLPS and evaluated before and after a competition period. The HRV was evaluated by a spectral analysis of the time series composed of R-R intervals obtained in the supine position and during a tilt test. The evaluation of stress markers consisted of measuring plasma catecholamines, cortisol and free testosterone. The results demonstrated that the training load used during the competition period did not cause significant changes in the autonomic modulation of HRV. This affirmation is supported by the absence of change in oscillations of low frequency (LF: 0,04-0,15Hz), that corresponding to sympathetic and parasympathetic modulations, and high frequency (HF:0,15-05Hz), that corresponding only to parasympathetic modulations of HRV. Additionally, no changes were observed in plasma concentrations of catecholamines, free testosterone, cortisol and, consequently, in testosterone/cortisol ratio, when pre-competition and post-competition values were compared. In summary, our findings suggest that the use of SLPS in basketball athletes presented balance between workloads and recovery periods. However, further investigations are needed, including in other sports, so that we can evaluate the effects of SLPS on cardiac autonomic modulation and stress markers evaluated in this study.

Cardiac autonomic modulation is determined by gender and is independent of aerobic physical capacity in healthy subjects.

BackgroundAerobic physical capacity plays an important role in reducing morbidity and mortality rates in subjects with cardiovascular diseases. This action is often related to an improvement in the autonomic modulation of heart rate variability (HRV). However, controversies remain regarding the effects of physical training on cardiac autonomic control in healthy subjects. Therefore, our objective was to investigate whether aerobic capacity interferes with the autonomic modulation of HRV and whether gender differences exist.MethodsHealthy men and women (N=96) were divided into groups according to aerobic capacity: low (VO2: 22-38 ml/kg-1 min-1), moderate (VO2: 38-48 ml/kg-1 min-1) and high (VO2 >48 ml/kg-1 min-1.) We evaluated the hemodynamic parameters and body composition. The autonomic modulation of HRV was investigated using spectral analysis. This procedure decomposes the heart rate oscillatory signal into frequency bands: low frequency (LF=0.04-0.15Hz) is mainly related to sympathetic modulation, and high frequency (HF=0.15-0.5Hz) corresponds to vagal modulation.ResultsAerobic capacity, regardless of gender, determined lower values of body fat percentage, blood pressure and heart rate. In turn, the spectral analysis of HRV showed that this parameter did not differ when aerobic capacity was considered. However, when the genders were compared, women had lower LF values and higher HF values than the respective groups of men.ConclusionThe results suggest that aerobic physical capacity does not interfere with HRV modulation; however, the cardiac modulatory balance differs between genders and is characterized by a greater influence of the autonomic vagal component in women and by the sympathetic component in men.

Physical therapy for airway clearance improves cardiac autonomic modulation in children with acute bronchiolitis

BackgroundThe effects of physical therapy on heart rate variability (HRV), especially in children, are still inconclusive. ObjectiveWe investigated the effects of conventional physical therapy (CPT) for airway clearance and nasotracheal suction on the HRV of pediatric patients with acute bronchiolitis. Method24 children were divided into two groups: control group (CG, n=12) without respiratory diseases and acute bronchiolitis group (BG, n=12). The heart rate was recorded in the BG at four different moments: basal recording (30 minutes), 5 minutes after the CPT (10 minutes), 5 minutes after nasotracheal suction (10 minutes), and 40 minutes after nasotracheal suction (30 minutes). The CG was subjected to the same protocol, except for nasotracheal suction. To assess the HRV, we used spectrum analysis, which decomposes the heart rate oscillations into frequency bands: low frequency (LF=0.04-0.15Hz), which corresponds mainly to sympathetic modulation; and high frequency (HF=0.15-1.2Hz), corresponding to vagal modulation. ResultsUnder baseline conditions, the BG showed higher values in LF oscillations, lower values in HF oscillations, and increased LF/HF ratio when compared to the CG. After CPT, the values for HRV in the BG were similar to those observed in the CG during basal recording. Five minutes after nasotracheal suction, the BG showed a decrease in LF and HF oscillations; however, after 40 minutes, the values were similar to those observed after application of CPT. ConclusionsThe CPT and nasotracheal suction, both used for airway clearance, promote improvement in autonomic modulation of HRV in children with acute bronchiolitis.

Frequency Ranges of Heart Rate Variability Related to Autonomic Nerve Activity in the Mouse

Mice have gained more and more attention in recent years and been widely used in transgenic experiments. Although the number of researches on the heart rate variability (HRV) of mice has been gradually increasing, a consensus on the frequency ranges of autonomic modulation has not been established. Therefore, the main purpose of this study was to find a HRV “prototype” for conscious mice in the state of being motionless and breathing regularly (called “genuinely resting”), and to determine the frequency ranges corresponding to the autonomic modulation. Further, whether these frequencies will change when the mice move freely was studied to evaluate the feasibility of the HRV spectrum as an index of the autonomic modulation of mice. The recording sites were specially arranged to simultaneously obtain the electrocardiography and electromyography data to be provided for the use of HRV analysis and motion monitoring, respectively. The states of being motionless and breathing regularly as judged from the electromyography results were selected as a genuine resting state of a conscious mouse. The frequencies related to autonomic modulation of HRV were determined by comparing the spectrum changes before and after blockades of the autonomic tone by different pharmaceutical agents in both the genuine resting state and freely moving states. Our results showed that the HRV of mice is not suitable for indexing sympathetic modulation; however, it is possible to use the spectral power in the frequency range between 0.1 and 1 Hz as an index of parasympathetic modulation.