Highlights There is a high prevalence of hypokalemia among patients with COVID-19 pneumonia. This suggests the presence of a disorder in the renin-angiotensin system activity. Hypokalemia is associated with requiring invasive mechanical ventilation. Hypokalemia seems to be a sensitive biomarker of severity-progression of COVID-19. Serum levels of potassium should be closely monitored in these patients.

Background: Exercise-based cardiac rehabilitation (CR) programs are used for improving prognosis and quality of life in patients with cardiovascular disease (CVD). Nonetheless, adherence to these programs is low, and exercise-based CR programs based on virtual reality (i.e., exergaming) have been proposed as an alternative to conventional CR programs. However, whether exergaming programs are superior to conventional CR programs in patients with CVD is not known. Objective: This systematic review with meta-analysis was conducted to explore whether exergaming enhances exercise capacity, quality of life, mental health, motivation, and exercise adherence to a greater extent than conventional CR programs in patients with CVD. Method: Electronic searches were carried out in PubMed, Embase, Web of Science, and Cumulative Index to Nursing and Allied Health Literature databases up to June 2021. Meta-analyses were performed using robust variance estimation with small-sample corrections. The effect sizes were calculated as the mean differences (MD) or standardized mean differences (SMD) as appropriate. The SMD magnitude was classified as trivial (<0.20), small (0.20–0.49), medium (0.50–0.79), or large (≥0.80). Heterogeneity was interpreted based on the I2 statistics as low (25%), moderate (50%), or high (75%). Results: Pooled analyses showed no differences between exergaming and conventional CR programs for enhancing exercise capacity (i.e., distance covered in the six-minute walk test) (MD+ = 14.07 m (95% confidence interval (CI) −38.18 to 66.32 m); p = 0.426) and mental health (SMD+ = 0.17 (95% CI −0.36 to 0.70); p = 0.358). The results showed a small, statistically nonsignificant improvement in quality of life in favor of exergaming (SMD+ = 0.22 (95% CI = −0.37 to 0.81); p = 0.294). Moderate heterogeneity was found for exercise capacity (I2 = 53.7%), while no heterogeneity was found for quality of life (I2 = 3.3%) and mental health (I2 = 0.0%). Conclusions: Exergaming seems not to be superior to conventional CR programs for improving exercise capacity, quality of life, or mental health in patients with CVD.

Background Exercise-based cardiac rehabilitation (CR) is considered an effective treatment for enhancing endothelial function in patients with heart failure (HF). However, recent studies have been published and the optimal “dose” of exercise required to increase the benefits of exercise-based CR programmes on endothelial function is still unknown. Objectives (a) To estimate the effect of exercise-based CR on endothelial function, assessed by flow-mediated dilation (FMD), in patients with HF; (b) to determine whether high-intensity interval training (HIIT) is better than moderate-intensity training (MIT) for improving FMD; and (c) to investigate the influence of exercise modality (i.e. resistance exercise vs. aerobic exercise and combined exercise vs. aerobic exercise) on the improvement of endothelial function. Methods Electronic searches were carried out in PubMed, Embase, and Scopus up to February 2022. Random-effects models of between-group mean differences were estimated. Heterogeneity analyses were performed by means of the chi-square test and I2 index. Subgroup analyses and meta-regressions were used to test the influence of potential moderator variables on the effect of exercise. Results We found a FMD increase of 3.09% (95% confidence interval [CI] = 2.01, 4.17) in favour of aerobic-based CR programmes compared with control groups in patients with HF and reduced ejection fraction (HFrEF). However, the results of included studies were inconsistent (p < .001; I2 = 95.2%). Higher FMD improvement was found in studies which were randomised, reported radial FMD, or performed higher number of training sessions a week. Moreover, HIIT enhanced FMD to a greater extent than MIT (2.35% [95% CI = 0.49, 4.22]) in patients with HFrEF. Insufficient data prevented pooled analyses for the effect of exercise in patients with HF and preserved ejection fraction and the influence of exercise modality on the improvement of endothelial function. Conclusion Aerobic-based CR is a non-pharmacological treatment for enhancing endothelial function in patients with HFrEF. However, higher training frequency and HIIT induce greater adaptation of endothelial function in these patients, which should betaken into consideration when designing exercise-based CR programmes. Trial registration The protocol was prospectively registered on the PROSPERO database (CRD42022304687).

The verification phase (VP) has been proposed as an alternative to the traditional criteria used for the determination of the maximum oxygen uptake (VO2 max) in several populations. Nonetheless, its validity in patients with heart failure with reduced ejection fraction (HFrEF) remains unclear. Therefore, the aim of this study was to analyse whether the VP is a safe and suitable method to determine the VO2 max in patients with HFrEF. Adult male and female patients with HFrEF performed a ramp-incremental phase (IP), followed by a submaximal constant VP (i.e., 95% of the maximal workload during the IP) on a cycle ergometer. A 5-min active recovery period (i.e., 10 W) was performed between the two exercise phases. Group (i.e., median values) and individual comparisons were performed. VO2 max was confirmed when there was a difference of ≤ 3% in peak oxygen uptake (VO2 peak) values between the two exercise phases. Twenty-one patients (13 males) were finally included. There were no adverse events during the VP. Group comparisons showed no differences in the absolute and relative VO2 peak values between both exercise phases (p = 0.557 and p = 0.400, respectively). The results did not change when only male or female patients were included. In contrast, individual comparisons showed that the VO2 max was confirmed in 11 patients (52.4%) and not confirmed in 10 (47.6%). The submaximal VP is a safe and suitable method for the determination of the VO2 max in patients with HFrEF. In addition, an individual approach should be used because group comparisons could mask individual differences.

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