Interval training based on ventilatory anaerobic threshold increases cardiac vagal modulation and decreases high-sensitivity c-reative protein: randomized clinical trial in coronary artery disease

Beneficial impacts of physical activity on heart rate variability: A systematic review and meta-analysis

BACKGROUND

Cardiovascular diseases (CVD) are the leading causes of morbidity and mortality. Heart rate variability (HRV) represents the modulatory capacity of the autonomous nervous system and influences mortality. By surveying this meta-analysis, we investigated the impact of physical activity on HRV.

METHODS

Databases, online journal libraries and clinical trial registries were searched for publications of randomized controlled and non-randomized controlled trials concerning adults with coronary artery disease (CAD)/ischemic heart disease (IHD), congestive heart failure (CHF), peripheral arterial disease (PAD) or after acute coronary syndrome (ACS) joining an intervention group with physical activity or a control group with usual care or no intervention. Extracted time-domain and frequency-domain parameter of HRV were analyzed in a meta-analysis using a random effect model. Subgroup analyses concerning intervention type, study design and type of heart disease and sensitivity analysis were performed.

RESULTS

Significant results were obtained for RR-Interval (p = 0.05) and standard deviation of Normal-to-Normal intervals (SDNN) (p = 0.01) for short-term assessment and for the ratio of low-frequency power (LF) to high-frequency power (HF) (p = 0.05) for 24-hour assessment. Subgroup analyses also resulted significant: root-mean-square difference of successive normal R-R intervals (RMSSD) (p = 0.01), SDNN (p = 0.02) and HF (p < 0.01) concerning CHF.

CONCLUSION

We were able to demonstrate the positive impact of physical activity on HRV, especially in patients with CHF. Cardiac rehabilitation exercise programs need to be individualized to identify the most beneficial method of training for improving the prognosis of patients with CVD.

Comparison of intradialytic continuous and interval training on hemodynamics and dialysis adequacy: A crossover randomized controlled trial

AIM

Circulating blood volume (BV) during exercise changes depending on the intensity and duration, and post-exercise hypotension is observed after continuous exercise. We investigated the safety and efficacy of both interval and continuous IDE at anaerobic threshold (AT) levels with respect to hemodynamic stability and dialysis efficiency.

METHODS

In this crossover randomized controlled trial, 16 patients on haemodialysis were subjected to three trial arms, including non-IDE, interval-IDE, and continuous-IDE arms. Systolic blood pressure (SBP), BV, and ultraviolet absorbance - an indicator of dialysis efficiency - were continuously measured, and each change was compared between the three arms by two-way analysis of variance.

RESULTS

Continuous IDE decreased SBP from post-exercise to the end of dialysis compared with baseline (pre 142.8 ± 19.0 vs. post 127.5 ± 24.5 mmHg, p = .02), whereas interval IDE maintained better SBP levels post-exercise (pre 139.9 ± 17.1 vs. post 140.1 ± 15.8 mmHg, p = 1.0) than continuous IDE (non-IDE 133.2 ± 19.9 vs. interval 140.1 ± 15.8 vs. continuous 127.5 ± 24.5 mmHg, p = .04). Moreover, interval IDE caused less tiredness and few symptoms (p < .05), despite reaching higher intensity than continuous IDE (p = .001). The BV of each IDE arm decreased during exercise and recovered post-exercise to the same level as non-IDE. Ultraviolet absorbance was not different between each arm (p = .16).

CONCLUSION

AT-level interval IDE maintains better hemodynamic stability from post-exercise to the end of dialysis and may represent a novel approach that can be effectively performed with fewer symptoms.

Effects of High Intensity Interval Training versus Sprint Interval Training on Cardiac Autonomic Modulation in Healthy Women

BACKGROUND

For the prevention of cardiovascular diseases, the practice of physical exercises is an effective strategy in improving or maintaining cardiorespiratory health; however, a lack of time is a barrier to access and interval training appears as possible facilitator. This study aims to compare the effects of two interval training protocols on cardiac autonomic modulation in healthy women.

METHODS

we conducted a randomized clinical trial with 43 women with a mean age of 29.96 ± 6.25 years, allocated into two groups; high-intensity interval training (HIIT) consisting of four four-minute high-intensity sprints interspersed with three minutes of active recovery and the Sprint interval training (SIT) with four 30-s sprints all-out, interspersed with four minutes of recovery (active or passive).

RESULTS

the HIIT group presented better results for the patterns without variation (0V) variables (p = 0.022); Shannon entropy (p = 0.004) Conditional Entropy (p = 0.025). However, there was a significant group effect for some variables, Oxygen Volume (VO2) (p = 0.004), Square root of the mean quadratic differences between the adjacent normal R-R intervals (p = 0.002) and standard deviation of all normal R-R intervals recorded in a time interval (p = 0.003), demonstrating an improvement independent of the protocol.

CONCLUSION

we conclude that eight weeks of interval training were able to produce positive effects on cardiac autonomic modulation in healthy women, with better results for HIIT in this population.

Hydration Influence on the Autonomic Recovery of the Coronary Diseases Patient: Geometric Indices Analysis

Purpose: To evaluate the recovery period of autonomic modulation, through geometric indices of heart rate variability (HRV), on coronary artery disease (CAD) patients submitted to a cardiovascular rehabilitation session (CR), associated with hydration. Methods: Thirty male participants of a CR program, diagnosed with CAD were submitted to the control (CP) and hydration protocol (HP) characterized by a CR session. Only during HP were the participants given 8 equal portions of water. The water amount was determined through the hydric loss measured at the CP. During the protocols, the heart rate was measured beat-by-beat at rest (5-10 minutes[M1]) and at recovery (0-5 minutes [M2], 5-10 minutes [M3], 15-20 minutes [M4], 25-30 minutes [M5], 40-45 minutes [M6], 55-60 minutes [M7]) for the HRV analysis, performed by the geometric indices: TINN, RRTRI, SD1, SD2 and SD1/SD2 ratio. Results: Statistically significant differences were observed between the protocols (SD1, p_value = 0.022), moments (TINN, p_value = 0.001; SD1, p_value = 0.019; SD2, p_value = 0.001; SD1/SD2, p_value = 0.001) and moments vs. protocol interaction (SD1, p_value = 0.019). The SD1 index pointed to acceleration of parasympathetic recovery in the first minutes after exercising (HP recovery after M3 [86.07 ± 32.31%] vs. CP recovery after M5[86.43 ± 24.56]) and increase in global variability (TINN-HP remained increased in longer, until M5 (M1 83.10 ± 55.76 ms to M5 116.82 ± 67.54 ms) vs. CP that remained increased for a short time, until M2 (M1 77.93 ± 68.56 ms to M2 134.82 ± 56.08 ms). Conclusions: In CAD patients, hydration promoted a more efficient recovery on parasympathetic autonomic modulation and increased the global HRV in the recovery period.

Excess ischemic tachyarrhythmias trigger protection against myocardial infarction in hypertensive rats

Increased level of C-reactive protein (CRP) is a risk factor for cardiovascular diseases, including myocardial infarction and hypertension. Here, we analyzed the effects of CRP overexpression on cardiac susceptibility to ischemia/reperfusion (I/R) injury in adult spontaneously hypertensive rats (SHR) expressing human CRP transgene (SHR-CRP). Using an in vivo model of coronary artery occlusion, we found that transgenic expression of CRP predisposed SHR-CRP to repeated and prolonged ventricular tachyarrhythmias. Excessive ischemic arrhythmias in SHR-CRP led to a significant reduction in infarct size (IS) compared with SHR. The proarrhythmic phenotype in SHR-CRP was associated with altered heart and plasma eicosanoids, myocardial composition of fatty acids (FAs) in phospholipids, and autonomic nervous system imbalance before ischemia. To explain unexpected IS-limiting effect in SHR-CRP, we performed metabolomic analysis of plasma before and after ischemia. We also determined cardiac ischemic tolerance in hearts subjected to remote ischemic perconditioning (RIPer) and in hearts ex vivo. Acute ischemia in SHR-CRP markedly increased plasma levels of multiple potent cardioprotective molecules that could reduce IS at reperfusion. RIPer provided IS-limiting effect in SHR that was comparable with myocardial infarction observed in naïve SHR-CRP. In hearts ex vivo, IS did not differ between the strains, suggesting that extra-cardiac factors play a crucial role in protection. Our study shows that transgenic expression of human CRP predisposes SHR-CRP to excess ischemic ventricular tachyarrhythmias associated with a drop of pump function that triggers myocardial salvage against lethal I/R injury likely mediated by protective substances released to blood from hypoxic organs and tissue at reperfusion.

Exercise-based cardiac rehabilitation and parasympathetic function in patients with coronary artery disease: a systematic review and meta-analysis

PURPOSE

The effects of exercise-based cardiac rehabilitation (CR) on parasympathetic modulation are controversial. This systematic review and meta-analysis aims to (a) determine the effect of exercise-based CR on heart-rate-derived indices associated with cardiac parasympathetic modulation in resting and post-exercise conditions in coronary artery disease (CAD) patients and (b) identify the possible moderator variables of the effect of exercise-based CR on parasympathetic modulation.

METHODS

We searched CENTRAL and Web of Science up to November 2018 for the following terms: adult CAD patients, controlled exercise-based CR interventions and parasympathetic modulation measured in resting (vagal-related heart rate variability [HRV] indices of the root mean square of the differences in successive in RR interval [RMSSD] and high frequency [HF]) and post-exercise (heart rate recovery [HRR]) pre- and post-intervention. We estimated a random-effects model of standardised mean difference (SMD) and mean difference (MD) for vagal-related HRV indices and HRR, respectively. We assessed the influence of categorical and continuous variables.

RESULTS

The overall effect size showed significant differences in RMSSD (SMD₊ = 0.30; 95% confidence interval [CI] = 0.12-0.49) and HRR (MD₊ = 5.35; 95% CI = 4.08-6.61 bpm) in favour of the exercise-based CR group. The overall effect size showed no differences in HF between groups (SMD₊ = 0.14; 95% CI,  -0.12-0.40). Heterogeneity analyses reached statistical significance, with high heterogeneity for HF (p < 0.001; I² = 70%) and HRR (p < 0.001; I² = 85%). Analysis of the moderator variables showed that the effect on HRR is greater in young patients (p = 0.008) and patients treated with percutaneous intervention (p = 0.020).

CONCLUSIONS

Exercise-based CR improves the post-exercise parasympathetic function, with greater effects in younger CAD patients and in those who were revascularised with percutaneous intervention. The effects on resting parasympathetic function are more controversial due to methodological inconsistencies in measuring HRV, with the use of RMSSD recommended instead of HF because its results show higher consistency. Future studies involving women, focusing on methodological issues, and performing other training methods are needed to increase our knowledge about this topic.

Periodized Aerobic Interval Training Modifies Geometric Indices of Heart Rate Variability in Metabolic Syndrome

Background: Metabolic syndrome (MetS) influences the autonomic modulation, increasing the risk of cardiovascular events, which demands the identification of effective treatments for this population. Considering this, the study has the objective of evaluating the effects of periodized aerobic interval training (AIT) on geometrical methods of heart rate variability (HRV) on individuals with MetS. Methods: 52 individuals with MetS were considered for analysis. They were divided into two groups: aerobic interval training group (AITG; n = 26) and control group (CG; n = 26). The AITG performed 16 weeks of periodized AIT. For HRV analysis, the heart rate was recorded beat-by-beat at the beginning and the end of the AIT program and geometrical methods were used for analysis. Results: significant increase was observed for triangular index (RRtri, -1.25 ± 0.58 vs. 1.41 ± 0.57), standard deviation of distances from diagonal to points (SD1, -0.13 ± 1.52 vs. 4.34 ± 1.49), and standard deviation of distances from points to lines (SD2, -2.14 ± 3.59 vs. 11.23 ± 3.52) on AITG compared to CG. Significant differences were not observed for triangular interpolation of normal heartbeats interval histogram (TINN, -4.05 ± 17.38 vs. 25.52 ± 17.03) and SD1/SD2 ratio (0.03 ± 0.02 vs. 0.00 ± 0.02). Qualitative analysis of the Poincaré plot identified increase on dispersion of both short and long-term intervals between successive heartbeats (RR interval) on AITG after the AIT program. Conclusion: geometric indices of HRV suggest an increase in cardiac autonomic modulation in individuals with MetS after 16 weeks of periodized AIT.

Effects of a new approach of aerobic interval training on cardiac autonomic modulation and cardiovascular parameters of metabolic syndrome subjects

OBJECTIVE

To evaluate the effects of 16 weeks of periodized aerobic interval training (AIT) on cardiac autonomic modulation and cardiovascular parameters of metabolic syndrome (Mets) individuals.

SUBJECTS AND METHODS

The sample was composed of 52 subjects with a diagnosis of Mets, allocated into two groups: AIT (AITG; n = 26) and control (CG; n = 26). The AITG was submitted to a periodized AIT program, over 16 weeks, while CG was not submitted to any training program. To evaluate the autonomic modulation and cardiovascular parameters in both groups, heart rate variability (HRV) indices, blood pressure (BP), and heart rate (HR) were measured at the beginning and end of the training.

RESULTS

Statistically significant differences were not observed in HFms2 (high frequency in milisseconds), LFnu (low frequency in normality unit), HFnu (high frequency in normality unit), and LF/HF ratio indices, or in the cardiovascular parameters BP and HR when comparing the AITG with the CG. However, significant increases in rMSSD (root-means square differences of successive R-R intervals), LFms2 (low frequency in milliseconds), and SDNN (standard deviation of normal to normal intervals) were observed in the AITG.

CONCLUSION

Periodized AIT promoted positive effects on autonomic modulation of Mets subjects, characterized by an increase in the parasympathetic, sympathetic, and global modulation of this population. Additionally, cardiovascular parameter alterations were not observed in Mets subjects submitted to periodized AIT.

Heart rate variability: are you using it properly? Standardisation checklist of procedures

BACKGROUND

Heart rate variability is used as an assessment method for cardiac autonomic modulation. Since the Task Force's publication on heart rate variability in 1996, the European Heart Rhythm Association Position Paper in 2015 and a recent publication in 2017, attention has been paid to recommendations on using heart rate variability analysis methods, as well as their applications in different physiological conditions and clinical studies. This analysis has proved to be useful as a complementary tool for clinical evaluation and to assess the effect of non-pharmacological therapeutic interventions, such as physical exercise programmes, on cardiac autonomic modulation.

OBJECTIVE

The aim of this article is to make recommendations and to develop a checklist of normalisation procedures regarding the use of heart rate variability data collection and analysis methodology, focusing on the cardiology area and cardiac rehabilitation.

METHODS

Based on previous heart rate variability publications, this paper provides a description of the most common shortcomings of using the analysis methods and considers recommendations and suggestions on how to minimise these occurrences by using a specific checklist.

CONCLUSIONS

This article includes recommendations and a checklist regarding the use of heart rate variability collection and analysis methods. This work could help improve reporting on clinical evaluation and therapeutic intervention results and consequently, disseminate heart rate variability knowledge.

Water exercise in coronary artery disease patients, effects on heart rate variability, and body composition: A randomized controlled trial

BACKGROUND AND PURPOSE

It is important to assess the effectiveness and efficiency of water-based training programs in order to prescribe it as an alternative in cardiac rehabilitation for patients who have coronary artery disease (CAD). In these patients, autonomic dysfunction is an important physiological change strongly associated with adverse outcomes, morbidity, and mortality. Given that the beneficial effects of physical training in CAD patients have been traditionally evidenced with programs involving land-based aerobic exercises, this study aims to evaluate the effects of water aerobic exercise training (WAET) on the autonomic modulation of heart rate (HR) and body composition, in the rehabilitation of CAD patients.

METHODS

Twenty-six male subjects with CAD were randomly divided into a training group (n = 14), submitted to the WAET, and a control group (n = 12). The WAET consisted of 3 weekly sessions on alternate days, totalling 48 sessions. The analysis of HR variability was used to evaluate the autonomic modulation of HR, from the recording of R-R intervals for 15 min, at rest in the supine position, and the body composition was evaluated through the bioelectrical impedance analysis.

RESULTS

Only the training group participants had improvement in the HR variability indices; patterns without variation decreased (0V, p = .005) and an increase of patterns of two different variations (p < .001), Shannon entropy (p = .02), and normalized conditional entropy (p = .03), whereas the control group had an increase of 0V (p = .04) and a decrease of normalized conditional entropy (p = .01). All body composition variables remained unchanged.

CONCLUSIONS

The WAET protocol improved the cardiac autonomic modulation of patients with CAD and can be considered as exercise training strategy in cardiac rehabilitation programs.

Caracterização da variabilidade da frequência cardíaca em indivíduos com síndrome metabólica

RESUMO Introdução: A variabilidade da frequência cardíaca (VFC) tem sido considerada um mecanismo de modulação do sistema nervoso autônomo. A diminuição da VFC pode estar associada à síndrome metabólica (SM). Objetivo: Comparar a VFC e variáveis de saúde em indivíduos com e sem SM. Métodos: Cento e dezenove participantes foram divididos em dois grupos: sem SM (SSM, n = 68) e com SM (CSM, n = 51). Foi avaliada a análise espectral da VFC em repouso, durante teste cardiopulmonar de exercício (TCPE) e na recuperação em bandas de baixa frequência (LF = 0,04-0,15 Hz), alta frequência (HF = 0,15-0,4 Hz) e razão LF/HF. Adicionalmente, a frequência cardíaca (FC) de repouso (FCrep), FC máxima (FCmáx), pressão arterial sistólica (PAS) e diastólica (PAD), glicemia, perfil lipídico, consumo de oxigênio pico (VO2pico) e composição corporal foram avaliados. Resultados: A FCrep e o VO2pico não apresentaram diferenças entre o CSM e o SSM (73,3 ± 9,1 vs. 70,1 ± 11,0 bpm) (26,8 ± 4,6 vs. 28,1 ± 6,6 ml.kg-1.min-1), respectivamente. A VFC foi similar entre os grupos nos diferentes momentos analisados. A glicemia (99,8 ± 22,5 vs. 87,6 ± 8,6 mg/dl) foi superior no CSM comparado ao SSM. Os valores de triglicérides (159,5 ± 68,8 vs. 89,2 ± 34,3 mg/dl) e VLDL-c (31,9 ± 13,8 vs. 17,8 ± 6,9 mg/dl) foram superiores no CSM comparado ao SSM. O HDL-c (40,7 ± 11,5 vs. 49,3 ± 9,8 mg/dl) foi menor no CSM comparado ao SSM. O IMC (33,1 ± 4,7 vs. 30,8 ± 3,8 Kg/m²) foi superior no CSM comparado ao SSM. A PAS (128,6 ± 12,9 vs. 119,5 ± 11,3 mmHg) e a PAD (77,2 ± 10,5 vs. 72,9 ± 8,1 mmHg) foram superiores no CSM comparado ao SSM, p < 0,05. Conclusão: Os resultados sugerem que a presença de SM não é suficiente para provocar alterações nos índices de VFC em repouso, durante teste cardiopulmonar de exercício (TCPE) e na recuperação quando os pacientes são comparados a indivíduos sem a doença.