Effects of Moderate-Intensity Training Under Cyclic Hypoxia on Cardiorespiratory Fitness and Hematological Parameters in People Recovered From COVID-19: The Aerobicovid Study

Effectiveness of tele-exercise training on physical fitness, functional capacity, and health-related quality of life in non-hospitalized individuals with COVID-19: The COFIT-HK study

Background

The use of tele-exercise programs as an option for post-COVID-19 rehabilitation has been suggested, but its effectiveness in non-hospitalized individuals is not well understood.

Objective

This study aimed to determine the effectiveness of an 8-week tele-exercise training program (COFIT-HK) on physical fitness, functional capacity, and health-related quality of life (HRQoL) in non-hospitalized post-COVID-19 individuals.

Methods

Forty-one non-hospitalized individuals (age:47.4 ± 7.8 yrs) who had COVID-19 history were divided into two groups: the tele-exercise training group (TELE; n = 21) and the non-intervention control group (CON; n = 20). TELE engaged in online supervised multicomponent low-to-moderate intensity exercise training (including respiratory muscle, aerobic, and resistance training) three times per week, whereas CON received standardized educational leaflets based on World Health Organization (WHO) guidelines for post-COVID-19-related illness rehabilitation only. Various components of physical fitness, functional capacity, and HRQoL were assessed at baseline and after the 8-week intervention.

Results

TELE showed significant improvements in handgrip strength, arm flexibility, functional lower extremity endurance, and HRQoL after the 8-week intervention (all p < 0.05, ES = 0.50-1.10). When comparing the groups, TELE demonstrated significantly greater improvements in both the physical and mental component summary scores of HRQoL compared to CON (both p < 0.05). Other outcomes did not reveal significant group differences.

Conclusion

Our tele-exercise intervention was effective in improving physical fitness, functional capacity and HRQoL among non-hospitalized post-COVID-19 individuals. Further research is needed to explore the utility and limitations of tele-exercise programs for post-COVID-19 rehabilitation and beyond.

Effect of Physical Exercise-Based Rehabilitation on Long COVID: A Systematic Review and Meta-analysis

PURPOSE

The number of persons living with post-coronavirus disease 2019 (COVID-19) conditions or long COVID continues to rise worldwide; however, the etiology and the treatment of long COVID remain nebulous. Therefore, efficient, feasible, and cost-effective therapeutic strategies for a large population with long COVID remain warranted. Physical exercise-based rehabilitation is a promising strategy for long COVID, although its therapeutic effects remain to be determined. This systematic review and meta-analysis aimed to examine the effects of physical exercise-based rehabilitation on long COVID.

METHODS

The electronic databases Medline, Embase, Global Health (Ovid), CINAHL (EBSCO), Web of Science, WHO Global Research Database on COVID-19, LitCovid, and Google Scholar were searched from their inception to November 2022. The identified articles were independently screened by three reviewers, and a random-effects model was used to determine the mean differences in the meta-analysis.

RESULTS

Twenty-three studies involving 1579 individuals who had COVID-19 (752 women) were included. Physical exercise-based rehabilitation showed beneficial effects on long COVID-related symptoms characterized by dyspnea, fatigue, and depression, as well as on the 6-min walk test, forced expiratory volume in 1 s/forced vital capacity, and quality of life in people who had COVID-19.

CONCLUSIONS

Physical exercise-based rehabilitation is a potential therapeutic strategy against long COVID and can be applied as a routine clinical practice in people who have recovered from COVID-19. However, customized physical exercise-based rehabilitation programs and their effects on specific types of long COVID require future large-scale studies.

Rehabilitation and COVID-19: systematic review by Cochrane Rehabilitation

INTRODUCTION

Until the last update in February 2022, the Cochrane Rehabilitation COVID-19 Evidence-based Response (REH-COVER) action identified an increasing volume of evidence for the rehabilitation management of COVID-19. Therefore, our aim was to identify the best available evidence on the effectiveness of interventions for rehabilitation for COVID-19-related limitations of functioning of rehabilitation interest in adults with COVID-19 or post COVID-19 condition (PCC).

EVIDENCE ACQUISITION

We ran the searches on February 17th, 2023, in the following databases: PubMed, EMBASE, CENTRAL, CINHAL, and the Cochrane COVID-19 Study Register, applying a publication date restriction to retrieve only papers published in 2022. To retrieve papers published before 2022, we screened the reference lists of previous publications included in the REH-COVER action, covering papers from early 2020 to the end of 2022. This current review includes only randomised controlled trials and concludes the rapid living systematic reviews of the Cochrane Rehabilitation REH-COVER action. The risk of bias and certainty of evidence were evaluated in all studies using the Cochrane Risk of Bias tool and GRADE, respectively. We conducted a narrative synthesis of the evidence. PROSPERO registration number: CRD42022374244.

EVIDENCE SYNTHESIS

After duplicate removal, we identified 18,950 individual records and 53 RCTs met the inclusion criteria. Our findings suggest that the effect of breathing and strengthening exercise programs on dyspnea and physical exercise capacity compared to no treatment in non-severe COVID-19 patients is uncertain. Multicomponent telerehabilitation may slightly increase physical exercise capacity compared to educational intervention in adults with PCC. There is, however, uncertainty about its effect on lung function and physical exercise capacity when compared to no treatment. Finally, the effect of inspiratory muscle training on maximal inspiratory pressure compared to no treatment in adults with PCC is uncertain.

CONCLUSIONS

Interventions that are part of comprehensive pulmonary rehabilitation approaches may benefit dyspnea and exercise tolerance in adults with COVID-19 and PCC. The available evidence has several methodological limitations that limit the certainty of evidence and the clinical relevance of findings. Therefore, we cannot provide robust suggestions for practice. While high-quality RCTs are being conducted, clinicians should consider using high-quality evidence from other pulmonary conditions to rehabilitate patients with COVID-19 or PCC using context-specific interventions.

Intermittent Hypoxia Conditioning: A Potential Multi-Organ Protective Therapeutic Strategy

Severe hypoxia can induce a range of systemic disorders; however, surprising resilience can be obtained through sublethal adaptation to hypoxia, a process termed as hypoxic conditioning. A particular form of this strategy, known as intermittent hypoxia conditioning hormesis, alternates exposure to hypoxic and normoxic conditions, facilitating adaptation to reduced oxygen availability. This technique, originally employed in sports and high-altitude medicine, has shown promise in multiple pathologies when applied with calibrated mild to moderate hypoxia and appropriate hypoxic cycles. Recent studies have extensively investigated the protective role of intermittent hypoxia conditioning and its underlying mechanisms using animal models, demonstrating its potential in organ protection. This involves a range of processes such as reduction of oxidative stress, inflammation, and apoptosis, along with enhancement of hypoxic gene expression, among others. Given that intermittent hypoxia conditioning fosters beneficial physiological responses across multiple organs and systems, this review presents a comprehensive analysis of existing studies on intermittent hypoxia and its potential advantages in various organs. It aims to draw attention to the possibility of clinically applying intermittent hypoxia conditioning as a multi-organ protective strategy. This review comprehensively discusses the protective effects of intermittent hypoxia across multiple systems, outlines potential procedures for implementing intermittent hypoxia, and provides a brief overview of the potential protective mechanisms of intermittent hypoxia.

Effectiveness, implementation, and monitoring variables of intermittent hypoxic bicycle training in patients recovered from COVID-19: The AEROBICOVID study

Hypoxic exposure is safely associated with exercise for many pathological conditions, providing additional effects on health outcomes. COVID-19 is a new disease, so the physiological repercussions caused by exercise in affected patients and the safety of exposure to hypoxia in these conditions are still unknown. Due to the effects of the disease on the respiratory system and following the sequence of AEROBICOVID research work, this study aimed to evaluate the effectiveness, tolerance and acute safety of 24 bicycle training sessions performed under intermittent hypoxic conditions through analysis of peripheral oxyhemoglobin saturation (SpO₂), heart rate (HR), rate of perceived exertion (RPE), blood lactate concentration ([La^-]) and symptoms of acute mountain sickness in patients recovered from COVID-19. Participants were allocated to three training groups: the normoxia group (G_N) remained in normoxia (inspired fraction of O₂ (FiO₂) of ∼20.9%, a city with 526 m altitude) for the entire session; the recovery hypoxia group (G_HR) was exposed to hypoxia (FiO₂ ∼13.5%, corresponding to 3,000 m altitude) all the time except during the effort; the hypoxia group (G_H) trained in hypoxia (FiO₂ ∼13.5%) throughout the session. The altitude simulation effectively reduced SpO₂ mean with significant differences between groups G_N, G_HR, and G_H, being 96.9(1.6), 95.1(3.1), and 87.7(6.5), respectively. Additionally, the proposed exercise and hypoxic stimulus was well-tolerated, since 93% of participants showed no or moderate acute mountain sickness symptoms; maintained nearly 80% of sets at target heart rate; and most frequently reporting session intensity as an RPE of "3" (moderate). The internal load calculation, analyzed through training impulse (TRIMP), calculated using HR [TRIMP_HR = HR * training volume (min)] and RPE [TRIMP_RPE = RPE * training volume (min)], showed no significant difference between groups. The current strategy effectively promoted the altitude simulation and monitoring variables, being well-tolerated and safely acute exposure, as the low Lake Louise scores and the stable HR, SpO₂, and RPE values showed during the sessions.