Caracterização da variabilidade da frequência cardíaca em indivíduos com síndrome metabólica

Effects of moderate-intensity intermittent hypoxic training on health outcomes of patients recovered from COVID-19: the AEROBICOVID study protocol for a randomized controlled trial

Background

Recent studies point to a lower number and reduced severity of cases in higher altitude cities with decreased oxygen concentration. Specific literature has shown several benefits of physical training, so, in this sense, physical training with hypoxic stimulus appears as an alternative that supports the conventional treatments of the COVID-19 patient’s recovery. Thus, this study’s primary aim is to analyze the effects of moderate-intensity intermittent hypoxic training on health outcomes in COVID-19 recovered patients.

Methods

A clinical trial controlled double-blind study was designed. Participants (30–69 years old) will be recruited among those with moderate to severe COVID-19 symptoms, approximately 30 days after recovery. They will be included in groups according to the training (T) and recovery (R) association with hypoxia (H) or normoxia (N): (a) T_H:R_H, (b) T_N:R_H, (c) T_N:R_N, and last (d) the control group. The 8-week exercise bike intervention will be carried out with a gradual load increase according to the established periods, three times a week in sets of 5 min, 90 to 100% of the anaerobic threshold (AT), and a 2.5-min break. Blood will be collected for genotyping. First, after 4 weeks (partial), after 8 weeks, and later, 4 weeks after the end of the physical training intervention, participants will perform assessments. The primary outcome is the maximum oxygen consumption (VO₂peak). The secondary outcomes include lung function, inflammatory mediators, hematological, autonomic parameters, AT, body composition analysis, quality of life, mental health, anthropometric measurements, and physical fitness. The statistical analysis will be executed using the linear regression model with mixed effects at a 5% significance level.

Discussion

This study is designed to provide evidence to support the clinical benefits of moderate-intensity intermittent hypoxic training as a part of the treatment of patients recovered from COVID-19. It may also provide evidence on the efficacy and safety of intermittent hypoxic training in different health conditions. Lastly, this study presents an innovative strategy enabling up to 16 participants in the same training session.

Trial registration

ClinicalTrials.gov RBR-5d7hkv. Registered after the start of inclusion on 3 November 2020 with the Brazilian Clinical Trials Registry

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-021-05414-2.

Effects of Different Periodization Strategies of Combined Aerobic and Strength Training on Heart Rate Variability in Older Women

ABSTRACT

Rodrigues, JAL, Santos, BC, Medeiros, LH, Gonçalves, TCP, and Júnior, CRB. Effects of different periodization strategies of combined aerobic and strength training on heart rate variability in older women. J Strength Cond Res 35(7): 2033-2039, 2021-The preservation of autonomic function has been proposed to be a key determinant of health and longevity. Periodization in combined training (CT) (strength plus aerobic exercise in the same session) might improve autonomic modulation. However, the specific influences of nonperiodized (NP), flexible nonlinear periodized (FNLP), and nonlinear periodized (NLP) strategies of CT on heart rate variability (HRV) are currently unknown. Therefore, we investigated the effects of NP, FNLP, and NLP strategies of CT on HRV in physically active women. In total, 54 physically active older women (61.6 ± 6.3 years) previously engaged in a regular exercise training were randomly allocated into 3 groups: NP, FNLP, and NLP. All the subjects performed 12 weeks of training, 3 times per week, with the sessions divided into aerobic (bicycle or treadmill) and strength exercises. Before and after the exercise training, we examined anthropometric, body composition, and HRV measures (low-frequency [LF], high-frequency [HF], LF/HF, and root mean square successive difference of RR intervals [RMSSD]) during rest, a maximum exercise test, and recovery post-test. Mixed-model measures were used, and statistical significance was set at α = 0.05. The waist circumference reduced only in the NP group (∆ = -2.01%). The RMSSD increased in the NLP (∆ = 76.5%) and LF/HF ratio increased in the FNLP (∆ = 34.51%) during the rest period. There were no differences during the exercise test and recovery after test for LF, HF, LF/HF, or RMSSD. In active women, nonlinear periodization strategies of CT improved one of the cardiovascular health outcomes because HRV is a direct predictor of cardiovascular risk.

β2 adrenergic interaction and cardiac autonomic function: effects of aerobic training in overweight/obese individuals

PURPOSE

To verify the influence of different volumes and intensities of aerobic exercise on cardiac autonomic function (CAF) through heart rate variability (HRV) analysis as well the influence of β2 adrenergic receptor (ADRB2) variants in overweight/obese individuals.

METHODS

70 physically inactive adults were randomly allocated into the following 16-week training: 1-high-intensity interval training (HIIT) (n = 25, 1 × 4 min bout at 85-95%HR peak, 3×/week), 4-HIIT (n = 26, 4 × 4 min bouts at 85-95%HR peak, interspersed with 3 min of recovery at 50-70%HR peak, 3×/week), and moderate continuous training (MCT) (n = 19, 30 min at 60-70%HR peak, 5×/week). Before and after the exercise training, anthropometric, BP, cardiorespiratory fitness, and HRV measures were evaluated. R-R intervals recorded for 10 min in a supine position at pre- and post-intervention were used to analyze HRV in the plot-Poincare indexes (SD1, SD2), and frequency-domain (LF, HF, LF/HF). Full blood samples were used for genotyping.

RESULTS

4-HIIT and MCT showed positive outcomes for almost all variables while 1-HIIT had a positive influence only on SBP and SD2 index. No associations were observed between isolated ADRB2 variants and changes in HRV. In the analysis of the interaction genotypes, all groups responded positively for the SD1 index of HRV and only the H1 (GG and CC) and H2 (GG and CG + GG) groups presented increases in the RMSSD index. Furthermore, there was an increase in the LF index only in the H3 (CC and AA + AG) and H4 (AA + AG and CG + GG) groups.

CONCLUSIONS

ADRB2 variants and aerobic exercise training are important interacting variables to improve autonomic function and other health variables outcomes in overweight or obese individuals.

Fed and fasted states on heart rate variability, hemodynamic heart rate and blood pressure in adults submitted to moderate aerobic exercise

Background

Heart rate variability (HRV) has proven to be a powerful non-invasive tool to investigate cardiac autonomic control and, seems to be influenced by nutritional status and exercise practice. However, the acute effects of fed or fasting states on HRV and blood pressure (BP) during low-to-moderate intensity aerobic exercise are currently unknown. Therefore, we investigated the baseline values and behavior of HRV, BP, and heart rate (HR) before and after low-to-moderate intensity aerobic exercise in fed and fasted states in healthy adults.

Methods

12 healthy individuals with mean age (SD) 59.0 (9.1) years performed two tests on a treadmill at 80% of the mean velocity of the 6-min walking test separated by 48 h: 12 h fasted (FST) or 1 h fed (FED). HRV, BP and HR were analyzed at rest, posttest, and at the third, fifth, and seventh minutes of recovery.

Results

HRV and HR presented no significant alterations between nutritional conditions. HR at baseline was not different between nutritional conditions. Diastolic blood pressure was increased during the fasted baseline state.

Conclusions

The results of the current study provide that 12 h overnight fasting does not seem to be enough to affect significant changes in the autonomic modulation in healthy adults submitted to low-to-moderate intensity aerobic exercise.