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

Introduction: Flavonoids are oral venoactive drugs frequently prescribed to relieve the symptoms of chronic venous disorders. Micronized purified flavonoid fraction (MPFF, commercial Daflon 1000 mg) is a preparation that contains mainly diosmin and a small fraction of hesperidin. Both active ingredients are flavonoids, known for their anti-inflammatory and antioxidant properties.Objective: Whether the MPFF can alter hemodynamic behavior was examined.Methods: Daflon 1,000 mg was administered for 60 days, and the hemodynamic parameters were measured during the circadian cycle.Results: There were no significant differences for systolic blood pressure (100.1 ± 10.6 mmHg vs. 104.8 ± 7.7 mmHg) or diastolic blood pressure (73.8 ± 3.1 mmHg vs. 76.4 ± 6.6 mmHg) before and after MPFF intake, respectively (p > 0.05). However, in sharp contrast, the heart rate reduced significantly after intake of MPFF (88.8 ± 10.5 bpm vs. 79.3 ± 9.7 bpm; p < 0.05). The mean blood pressure was negatively correlated with the heart rate (HR) in the afternoon (r = −0.450, p = 0.016). During this period, there was a decrease in vein inflammation and varicosity, as shown by magnetic resonance imaging.Conclusion: We reported a new effect of MPFF as an attenuator of the heart rate. Because venous insufficiency decreased during the observed drug administration period, further studies are needed to examine whether the ability of diosmin and hesperidin to reduce vein disorders is directly linked to their action on heart rate.