Severe loss of mechanical efficiency in COVID-19 patients

Effects of Exercise Rehabilitation on Cardiorespiratory Fitness in Long-COVID-19 Survivors: A Meta-Analysis

Background: Poor cardiorespiratory fitness poses the highest risk of mortality. Long-COVID-19 survivors exhibit a reduced cardiorespiratory fitness (CRF). While exercise rehabilitation, such as cardiopulmonary exercise, is used for long-COVID-19 survivors, the effects of exercise on CRF in this population remain inconclusive. In this study, we aim to systematically summarise and synthesise whether exercise rehabilitation improves CRF among long-COVID-19 survivors. Methods: A comprehensive search was performed through PubMed, CINAHL, Embase, Scopus, and the Cochrane Library (since their inception to November 2023) and study reference lists. Studies presenting the effects of exercise rehabilitation on CRF (peak oxygen consumption (VO2peak) and six-minute walk distance (6MWD)) in long-COVID-19 survivors were identified. The standardised mean difference (SMD), mean difference (MD), and 95% confidence interval (CI) were used for analyses. The certainty of evidence was measured using a Grading of Recommendation Assessment, Development and Evaluation approach. Results: Twelve eligible studies (five RCTs and seven non-RCTs) with 682 participants were analysed. The meta-analysis showed significantly improved 6MWDs (MD 76.47, 95% CI 59.19-93.71, low certainty) and significantly greater 6MWDs (SMD 0.85, 95% CI 0.11-1.59, very low certainty) in the exercise rehabilitation group compared to the control group. A significantly improved 6MWD was found in subgroups of young to middle-aged adults and subgroups of patients who undertook aerobic exercise combined with resistance and respiratory exercise and centre-based training programs. Conclusions: Exercise rehabilitation is effective for improving CRF, as measured by the 6MWD in long-COVID-19 survivors. Improvements are likely to be more pronounced in specific subgroups of young to middle-aged adults and patients undertaking aerobic exercise combined with resistance and respiratory exercise and centre-based training programs. However, recommendations for clinical practice are limited due to the very low evidence certainty.

Determinants of cardiorespiratory fitness measured by cardiopulmonary exercise testing in COVID-19 survivors: a systematic review with meta-analysis and meta‑regression

BACKGROUND

The relationship between cardiorespiratory fitness and its possible determinants in post-COVID-19 survivors has not been systematically assessed.

OBJECTIVES

To identify and summarize studies comparing cardiorespiratory fitness measured by cardiopulmonary exercise testing in COVID-19 survivors versus non-COVID-19 controls, as well as to determine the influence of potential moderating factors.

METHODS

We conducted a systematic search of MEDLINE/PubMed, Cochrane Library, EMBASE, Google Scholar, and SciELO since their inceptions until June 2022. Mean differences (MD), standard mean differences (SMD), and 95% confidence intervals (CI) were calculated. Subgroup and meta-regression analyses were used to evaluate potential moderating factors.

RESULTS

48 studies (3372 participants, mean age 42 years, and with a mean testing time of 4 months post-COVID-19) were included, comprising a total of 1823 COVID-19 survivors and 1549 non-COVID-19 controls. After data pooling, VO2 peak (SMD=1.0 95% CI: 0.5, 1.5; 17 studies; N = 1273) was impaired in COVID-19 survivors. In 15 studies that reported VO2 peak values in ml/min/kg, non-COVID-19 controls had higher peak VO2 values than COVID-19 survivors (MD=6.2, 95% CI: 3.5, 8.8; N = 905; I2=84%). In addition, VO2 peak was associated with age, time post-COVID-19, disease severity, presence of dyspnea, and reduced exercise capacity.

CONCLUSION

This systematic review provides evidence that cardiorespiratory fitness may be impaired in COVID-19 survivors, especially for those with severe disease, presence of dyspnea, and reduced exercise capacity. Furthermore, the degree of reduction of VO2 peak is inversely associated with age and time post-COVID.

Being fit in the COVID-19 era and future epidemics prevention: Importance of cardiopulmonary exercise test in fitness evaluation

Endurance and resistance physical activity have been shown to stimulate the production of immunoglobulins and boost the levels of anti-inflammatory cytokines, natural killer cells, and neutrophils in the bloodstream, thereby strengthening the ability of the innate immune system to protect against diseases and infections. Coronavirus disease 19 (COVID-19) greatly impacted people's cardiorespiratory fitness (CRF) and health worldwide. Cardiopulmonary exercise testing (CPET) remains valuable in assessing physical condition, predicting illness severity, and guiding interventions and treatments. In this narrative review, we summarize the connections and impact of COVID-19 on CRF levels and its implications on the disease's progression, prognosis, and mortality. We also emphasize the significant contribution of CPET in both clinical evaluations of recovering COVID-19 patients and scientific investigations focused on comprehending the enduring health consequences of SARS-CoV-2 infection.

Hospital and intensive care unit stay associated with body mass index affect cardiorespiratory fitness in patients with COVID-19

BACKGROUND

The effects of coronavirus disease 2019 (COVID-19) on the cardiorespiratory fitness of hospitalized and obese patients are of utmost relevance. This study aimed to analyze how hospital and intensive care unit (ICU) stay together with body mass index affect cardiorespiratory fitness in patients with COVID-19.

METHODS

251 participants (males, n = 118; females, n = 133) were assigned to four groups: non-hospitalized COVID-19 patients (n = 65, age: 45.3 years), hospitalized COVID-19 patients (n = 63, age: 57.6 years), COVID-19 patients admitted to the ICU (n = 61, age: 56.9 years), and control group (n = 62, age: 49.8 years). An incremental cardiopulmonary exercise test was performed between 3 and 6 weeks after medical discharge from hospital.

RESULTS

Higher peak oxygen uptake (VO2peak), ventilatory efficiency and power output were found in ICU patients with normal weight (NW) than in overweight (OW) (Mean difference: 0.1 L·min-1, -5.5, 29.0 W, respectively) and obese (OB) ICU patients (Mean difference: 0.1 L·min-1, -5.0, 26.2 W, respectively) (p < .05). In NW, OW and OB participants, higher VO2peak and power output were observed in control group compared with non-hospitalized (Mean difference: NW: 0.2 L·min-1, 83.3 W; OW: 0.2 L·min-1, 60.0 W; OB: 0.2 L·min-1, 70.9 W, respectively), hospitalized (Mean difference: NW: 0.2 L·min-1, 72.9 W; OW: 0.1 L·min-1, 58.3 W; OB: 0.2 L•min-1, 91.1 W, respectively) and ICU patients (Mean difference: NW: 0.1 L·min-1, 70.9 W; OW: 0.2 L·min-1, 91.1 W; OB: 0.3 L·min-1; 65.0 W, respectively) (p < .05).

CONCLUSIONS

The degree of severity of COVID-19, especially identified by hospitalization and ICU stay, together with obesity and overweight were key factors in reducing cardiorespiratory fitness in patients with COVID-19.

Effects of a telerehabilitation program and detraining on cardiorespiratory fitness in patients with post-COVID-19 sequelae: A randomized controlled trial

BACKGROUND

This study aimed to evaluate the effects of a 15-week telerehabilitation program and a detraining period on cardiorespiratory fitness and mechanical efficiency in patients with post-COVID-19 sequelae.

METHODS

131 patients with post-COVID-19 sequelae were randomly assigned to one of two groups: patients who carried out the supervised telerehabilitation program (TRG, n = 66) and a control group (CG, n = 65). An incremental cardiopulmonary exercise testing (CPET) was performed on cycle ergometer to compare cardioventilatory responses between experimental groups.

RESULTS

A significant increase in the CPET duration, peak power output, and mechanical efficiency was observed in TRG compared to CG after the telerehabilitation program (p ≤ 0.001). A significant increase in the CPET duration, peak power output, and mechanical efficiency was verified at 3 months compared to the pretest and after detraining in TRG (p < 0.001). A significant increase in peak oxygen uptake (V̇O2peak ) was identified after the intervention and in the detraining period compared to the pretest in both experimental groups (p < 0.001). A higher ventilatory efficiency was observed after the telerehabilitation program (p = 0.021) than in pretest only in TRG.

CONCLUSIONS

A 15-week supervised home telerehabilitation program improved exercise capacity, power output, and mechanical efficiency in TRG compared to a CG. The telerehabilitation program was not more effective in improving V̇O2peak than the activities of the CG. However, ventilatory efficiency was improved only after the telerehabilitation program. The reported results after the detraining period highlight the need to maintain the rehabilitation program over time.

Effect of different types of supervised exercise programs on cardiorespiratory and muscular fitness, pain, fatigue, mental health and inflammatory and oxidative stress biomarkers in older patients with post-COVID-19 sequelae "EJerSA-COVID-19": a randomized controlled trial

BACKGROUND

Many patients with COVID-19 present the so-called post-acute sequelae of COVID-19 such as fatigue, post-stress discomfort, dyspnea, headache, pain mental impairment, incapacity to perform daily physical tasks ant exercise intolerance. This study aims to investigate the effects of different exercise programs on physical and mental fitness, physical condition and biomarkers of the immune system and oxidative stress in older patients with post-COVID-19 sequelae.

METHODS

The sample will be made up of 120 eligible participants, over the age of 60 years who have had COVID-19 disease and are survivors and present persistent COVID-19 symptomatology diagnosed by the corresponding physician. The participants will be randomly assigned to the experimental groups: supervised endurance group (SEG, n = 30), supervised strength group (SSG, n = 30), supervised concurrent group (SCG, n = 30), which will perform the corresponding exercise program 3 days a week compared to the control group (CG, n = 30), which will not carry out a supervised exercise program. The design of this project will include measurements of four relevant dimensions; 1) Cardiorespiratory fitness; 2) Muscle fitness; 3) Pain and mental health; and 4) Biomarkers of inflammation and oxidative stress.

CONCLUSIONS

The results of this study will provide insights into the effects of different exercise programs on physical and mental fitness, physical condition and biomarkers of the immune system and oxidative stress in older patients with post-COVID-19 sequelae. These findings may be the basis for the formulation of health plans and rehabilitation programs that allow healthy aging and a reduction in the associated morbidity in patients with post-COVID-19 sequelae.

TRIAL REGISTRATION

NCT05848518. Registered on May 8, 2023.

Human motor neurons derived from induced pluripotent stem cells are susceptible to SARS-CoV-2 infection

Introduction

COVID-19 typically causes Q7 respiratory disorders, but a high proportion of patients also reports neurological and neuromuscular symptoms during and after SARSCoV-2 infection. Despite a number of studies documenting SARS-CoV-2 infection of various neuronal cell populations, the impact of SARS-CoV-2 exposure on motor neuronal cells specifically has not been investigated so far.

Methods

Thus, by using human iPSC-derived motor neurons (iPSC-MNs) we assessed: (i) the expression of SARS-CoV-2 main receptors; (ii) iPSC-MN infectability by SARS-CoV-2; and (iii) the effect of SARS-CoV-2 exposure on iPSC-MN transcriptome.

Results

Gene expression profiling and immunofluorescence (IF) analysis of the main host cell receptors recognized by SARS-CoV-2 revealed that all of them are expressed in iPSC-MNs, with CD147 and NRP1 being the most represented ones. By analyzing SARS-CoV-2 N1 and N2 gene expression over time, we observed that human iPSC-MNs were productively infected by SARS-CoV-2 in the absence of cytopathic effect. Supernatants collected from SARS-CoV-2-infected iPSC-MNs were able to re-infect VeroE6 cells. Image analyses of SARS-CoV-2 nucleocapsid proteins by IF confirmed iPSC-MN infectability. Furthermore, SARS-CoV-2 infection in iPSCMNs significantly altered the expression of genes (IL-6, ANG, S1PR1, BCL2, BAX, Casp8, HLA-A, ERAP1, CD147, MX1) associated with cell survival and metabolism, as well as antiviral and inflammatory response.

Discussion

These results suggest for the very first time that SARS-CoV-2 can productively infect human iPSC-derived MNs probably by binding CD147 and NRP1 receptors. Such information will be important to unveil the biological bases of neuromuscular disorders characterizing SARS-CoV-2 infection and the so called long-COVID symptoms.

Maximal oxidative capacity during exercise is associated with muscle power output in patients with long coronavirus disease 2019 (COVID-19) syndrome. A moderation analysis

BACKGROUND & AIMS

Long COVID syndrome (LCS) involves persistent symptoms experienced by many patients after recovering from coronavirus disease 2019 (COVID-19). We aimed to assess skeletal muscle energy metabolism, which is closely related to substrate oxidation rates during exercise, in patients with LCS compared with healthy controls. We also examined whether muscle power output mediates the relationship between COVID-19 and skeletal muscle energy metabolism.

METHODS

In this cross-sectional study, we enrolled 71 patients with LCS and 63 healthy controls. We assessed clinical characteristics such as body composition, physical activity, and muscle strength. We used cardiopulmonary exercise testing to evaluate substrate oxidation rates during graded exercise. We performed statistical analyses to compare group characteristics and peak fat oxidation differences based on power output.

RESULTS

The two-way analysis of covariance (ANCOVA) results, adjusted for covariates, showed that the patients with LCS had lower absolute maximal fatty acid oxidation (MFO), relative MFO/fat free mass (FFM), absolute carbohydrates oxidation (CHox), relative CHox/FFM, and oxygen uptake (V˙˙O2) at maximum fat oxidation (g min-1) than the healthy controls (P < 0.05). Moderation analysis indicated that muscle power output significantly influenced the relationship between LCS and reduced peak fat oxidation (interaction β = -0.105 [95% confidence interval -0.174; -0.036]; P = 0.026). Therefore, when muscle power output was below 388 W, the effect of the LCS on MFO was significant (62% in our study sample P = 0.010). These findings suggest compromised mitochondrial bioenergetics and muscle function, represented by lower peak fat oxidation rates, in the patients with LCS compared with the healthy controls.

CONCLUSION

The patients with LCS had lower peak fat oxidation during exercise compared with the healthy controls, potentially indicating impairment in skeletal muscle function. The relationship between peak fat oxidation and LCS appears to be mediated predominantly by muscle power output. Additional research should continue investigating LCS pathogenesis and the functional role of mitochondria.

Long-term impact of SARS-CoV-2 infection on cardiorespiratory fitness: a meta-analysis

Background

Despite surviving Coronavirus disease 2019 (COVID-19), its long-term impact is of concern. Low cardiorespiratory fitness is a strong predictor of all-cause mortality, and likely affected by multisystem impairments following COVID-19 infection. Accumulating evidence has identified the impact of COVID-19 on cardiorespiratory fitness level. However, the findings have been controversial. Conclusive evidence is still needed.

Objectives

This review aimed to systematically summarize and synthesize whether the SARS-CoV-2 infection diminishes cardiorespiratory fitness in COVID-19 survivors.

Design

The study design was a systematic review and meta-analysis.

Methods

A search was carried out using PubMed, CINAHL, Scopus, Embase and the Cochrane Library, together with reference lists (searching from their inception to January 2023). Observational studies investigating the impact of COVID-19 on outcomes relevant to cardiorespiratory fitness (i.e., peak oxygen uptake) were included. Weighted mean difference (WMD) and 95% confidence interval (CI) were used to identify a pooled effect estimate. Use of a random effects model was considered as the main method. Grading of Recommendation Assessment, Development and Evaluation approach was employed to determine the certainty of evidence. This meta-analysis was registered with PROSPERO (registration number: CRD42023393108).

Results

Seven eligible studies (4 cross-sectional, 2 cohort, and 1 case-control studies) involving 4,773 participants were included in this meta-analysis. A pooled effect estimates showed that patients in the surviving COVID-19 group had a significant reduction in peak oxygen uptake when compared to their counterparts in the non-COVID-19 group (WMD -6.70, 95%CI -9.34 to -4.06, low certainty). A subgroup analysis by age found that COVID-19 survivors in the young- to middle-aged and middle- to older-aged subgroups had significant reductions in peak oxygen uptake when compared to their counterparts in the non-COVID-19 group (WMD -5.31, 95%CI -7.69 to -2.94, low certainty; WMD -15.63, 95%CI -28.50 to -2.75, very low certainty, respectively). Subgroup analyses by symptom found that patients with moderate to severe symptoms in the surviving COVID-19 group had significantly lower peak oxygen uptake than their counterparts in the non-COVID-19 group (WMD -15.63, 95%CI -28.50 to -2.75, very low certainty).

Conclusion

The current meta-analysis concluded that patients in the COVID-19 survivors had poorer cardiorespiratory fitness than their counterparts in the non-COVID-19 group, but there is considerable uncertainty of evidence. Poorer cardiorespiratory fitness is likely to be more pronounced in COVID-19 survivors who are getting older and had severe symptoms, but it is uncertain whether such finding has a valuable in clinical context.

Systematic Review Registration

https://www.crd.york.ac.uk/PROSPERO/, CRD42023393108.

Observations of nemaline bodies in muscle biopsies of critically ill patients infected with SARS-CoV-2

Patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) who have been admitted to the intensive care unit (ICU) often face months of physical disability after discharge. To optimize recovery, it is important to understand the role of musculoskeletal alterations in critically ill patients infected with SARS-CoV-2. The main aim of the present study was to describe the presence and morphology of nemaline bodies found in the skeletal muscle tissue from critically ill patients infected with SARS-CoV-2. In n = 7 patients infected with SARS-CoV-2, ultrastructural characteristics of vastus lateralis muscle obtained on days 1-3 and days 5-8 following ICU admission were investigated in more detail with electron microscopy. Those muscle biopsies consistently showed variable degrees of myofiber necrosis and myofibrillar disorganization. In 4/7 (57%) patients on days 5-8, the Z-line material accumulated into nemaline bodies with a typical lattice-like appearance at higher magnification, similar to that found in nemaline myopathy. This study is the first to describe the disintegration of myofibrils and the accumulation of Z-line material into nemaline bodies in the skeletal muscle tissue obtained from critically ill coronavirus disease-19 patients following ICU admission, which should be interpreted primarily as a non-specific pathological response of extreme myofibrillar disintegration associated with myofiber necrosis.

Prevalence and clinical implications of abnormal body composition phenotypes in patients with COVID-19: a systematic review

BACKGROUND

The impact of body composition (BC) abnormalities on coronavirus disease 2019 (COVID-19) outcomes remains to be determined.

OBJECTIVE

We summarized the evidence on BC abnormalities and their relationship with adverse clinical outcomes in patients with COVID-19.

METHODS

A systematic search was conducted up until September 26, 2022 for observational studies using BC techniques to quantify skeletal muscle mass (or related compartments), muscle radiodensity or echo intensity, adipose tissue (AT, or related compartments), and phase angle (PhA) in adults with COVID-19. Methodological quality of studies was assessed using the Newcastle-Ottawa Scale. A synthesis without meta-analysis was conducted to summarize the prevalence of BC abnormalities and their significant associations with clinical outcomes.

RESULTS

We included 62 studies (69.4% low risk of bias) with 12 to 1,138 participants, except three with up to 490,301 participants. Using computed tomography and different cut-offs, prevalence ranged approximately from 22-90% for low muscle mass, 12-85% for low muscle radiodensity, 16-70% for high visceral AT. Using bioelectrical impedance analysis (BIA), prevalence of high fat mass was 51% and low PhA was 22-88%. Mortality was inversely related to PhA (3/4 studies) and positively related to intramuscular AT (4/5 studies), muscle echo intensity (2/2 studies), and BIA-estimated fat mass (2/2 studies). Intensive care unit admission was positively related to visceral AT (6/7 studies) and total AT (2/3 studies). Disease severity and hospitalization outcomes were positively related to intramuscular AT (2/2 studies). Inconsistent associations were found for the rest of BC measures and hospitalization outcomes.

CONCLUSIONS

Abnormalities in BC were prevalent in patients with COVID-19. Although conflicting associations were observed among certain BC abnormalities and clinical outcomes, higher muscle echo intensity (reflective of myosteatosis) and lower PhA were more consistently associated with greater mortality risk. Likewise, high IMAT and VAT were associated with mortality and ICU admission, respectively.

Evaluation of risk factors for COVID-19 severity or death and their relationship to metabolic pathways

Background

Since the state of alarm was declared due to the COVID-19 pandemic, hospitals have been the main ones in charge of registering the therapeutic follow-up of affected people. The analysis of these data has allowed those different biochemical markers have been identified as predictors of the severity of the disease, but most of the published studies tend to be eminently descriptive and do not propose a biochemical hypothesis to explain the alteration of the results they are showing. Our objective is to recognize the main metabolic processes that are occurring in COVID-19 patients, as well as the identification of clinical parameters that are decisive to predict the severity of the disease.

Methods

A multivariate analysis was carried out from the clinical parameters collected in the database of the HM hospitals in Madrid, to determine the most relevant variables to predict the severity of the disease. Chemometric methods allow these variables to be obtained by applying a classification strategy with PLS-LDA.

Findings and interpretation

The variables that most contribute to separation are age in men and, in both sexes, the concentration of lactate dehydrogenase, urea and C-reactive protein.Oxygen deficiency in the tissues, due to the loss of functionality of the lungs, could be affecting the muscle tissue with special severity. Inflammation and tissue damage is related to increased LDH and CRP. The loss of muscle mass and the increase in the concentration of urea and LDH is explained by the adaptation of muscle metabolism to this oxygen deficiency.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profits sectors.

Ultrasound imaging assessment of the diaphragm and abdominal muscles in people with a recent history of moderate Covid-19 infection and healthy participants: A cross-sectional pilot study

Coronavirus disease (Covid-19) is a highly infectious disease caused by the SARS-CoV-2 virus and is associated with a decrease of respiratory, physical, and psychological function, subsequently affecting quality of life. The aim of the present pilot study was to use ultrasound imaging (USI) to evaluate and compare the thickness of the diaphragm and abdominal muscles between individuals recently diagnosed with moderate Covid-19 infection and healthy individuals.

METHODS

A cross-sectional observational pilot study was performed. A total sample of 24 participants were recruited from a private medical center (Madrid, Spain): Covid-19 (n = 12) and healthy controls (n = 12). The external oblique (EO), internal oblique (IO), transversus abdominis (TrA), rectus abdominis (RA), interrecti distance (IRD) and diaphragm thickness were assessed using USI during inspiration, expiration and during contraction.

RESULTS

USI measurements of the thickness of EO, IO, TrA, RA, IRD and the diaphragm did not differ significantly between groups during inspiration, expiration or during contraction (all P > 0.05).

CONCLUSIONS

These preliminary results suggest that the morphology of the abdominal muscles and diaphragm is not altered in people with a recent history of moderate Covid-19 infection.

A metabolic readout of the urine metabolome of COVID-19 patients

Analysis of urine samples from COVID-19 patients by ¹H NMR reveals important metabolic alterations due to SAR-CoV-2 infection. Previous studies have identified biomarkers in urine that reflect metabolic alterations in COVID-19 patients. We have used ¹H NMR to better define these metabolic alterations since this technique allows us to obtain a broad profile of the metabolites present in urine. This technique offers the advantage that sample preparation is very simple and gives us very complete information on the metabolites present. To detect these alterations, we have compared urine samples from COVID-19 patients (n = 35) with healthy people (n = 18). We used unsupervised (Robust PCA) and supervised (PLS-LDA) multivariate analysis methods to evaluate the differences between the two groups: COVID-19 and healthy controls. The differences focus on a group of metabolites related to energy metabolism (glucose, ketone bodies, glycine, creatinine, and citrate) and other processes related to bacterial flora (TMAO and formic acid) and detoxification (hippuric acid). The alterations in the urinary metabolome shown in this work indicate that SARS-CoV-2 causes a metabolic change from a normal situation of glucose consumption towards a gluconeogenic situation and possible insulin resistance.

Reduced muscle strength in patients with long-COVID-19 syndrome is mediated by limb muscle mass

Understanding the impact of COVID-19 on muscle strength may help to elucidate the organ systems that contribute to acute and chronic COVID-19 sequelae. We questioned whether patients with postdischarge symptoms after COVID-19 had compromised muscle strength compared with a control group, and if this potential relationship was mediated by the lower appendicular lean mass index (ALMI). A total of 99 patients with long-COVID-19 and 97 control participants were screened. Maximal grip strength was assessed with a TKK 5101 digital dynamometer, and leg extension 1RM was measured using EGYM Smart Strength machines. Body composition (fat mass percentage, lean mass, visceral fat, and appendicular lean mass index) was determined using a whole body dual-energy X-ray densitometer. Results showed that grip strength and leg extension strength were significantly higher in controls than in COVID-19 survivors (mean [SD], 32.82 [10.01] vs. 26.94 [10.33] kg; difference, 5.87 kg; P < 0.001) and (mean [SD], 93.98 [33.73] vs. 71.59 [33.70] kg; difference, 22.38 kg; P < 0.001), respectively). The relationship between long-COVID syndrome and grip/leg strength levels was partly mediated by ALMI, which explained 52% of the association for grip strength and 39% for leg extension. Our findings provide novel insights into the mechanisms underlying the relationship between long-COVID syndrome and grip/leg strength levels, supporting the negative effects of long-COVID syndrome on muscle function.NEW & NOTEWORTHY The causes of post-COVID-19 syndrome are uncertain. Limb muscle wasting common to patients with COVID-19 limits daily activities and exercise. In this cross-sectional study, we found that patients with long-COVID-19 syndrome had significantly lower absolute and relative muscle strength measurements than control participants. Interestingly, we identified that these relationships were mostly mediated by limb muscle mass. Our data thus suggest that the evident reduced upper and lower muscle mass is a putative cause of-or contributor to-the functional limitation of patients with long-COVID-19 syndrome.

Impaired pulmonary and muscle function during moderate exercise in female patients recovered from SARS-CoV-2

This study aimed to assess pulmonary and muscle dysfunction by analyzing the slow component of oxygen uptake (VO2SC), and mechanical and ventilatory efficiency in adult women recovered from the severe acute respiratory syndrome coronavirus type II (SARS-CoV-2) during a constant load test. 32 women (N = 17 patients with SARS-CoV-2; N = 15 control group) performed two cardiopulmonary exercise tests (CPX) on a cycle ergometer. In the first test, the participants performed incremental CPX until extenuation. In the second test the participants performed a 10-min CPX at a constant load intensity (watts) corresponding to the first ventilatory threshold. There was a 48-72 h rest period between the two tests. There was a significant increase in the VO2SC in the patients recovered from SARS-CoV-2 (160.4 ± 60 mL min-1) in comparison with the healthy participants (59.6 ± 65 mL min-1) (P < 0.001). Mechanical efficiency significantly decreased in patients recovered from SARS-CoV-2 compared to the control group (P = 0.04). Ventilatory inefficiency significantly increased in the patients recovered from SARS-CoV-2 compared with the control group (P < 0.001). Adult women recovered from SARS-CoV-2 infection have important pulmonary and muscular dysfunction and fatigue which contributes to increasing the VO2SC and reducing mechanical and ventilatory efficiency during mild-moderate exercise at a constant load.

Relationship between the severity of persistent symptoms, physical fitness, and cardiopulmonary function in post-COVID-19 condition. A population-based analysis

The aim of this study was to determine the relationship between physical fitness, cardiopulmonary function and patient-reported severity of symptoms in people with post-COVID-19 condition. We examined ambulatory patients (n = 72) with post-COVID-19 condition who had a chronic symptomatic phase lasting > 12 weeks from the onset of symptoms, but had not been hospitalized for acute COVID-19. A comprehensive medical screening was conducted, including clinical history, symptomatology, comorbidities, body composition and physical activity levels. We then identified the relationship between physical fitness (cardiorespiratory fitness and muscular strength), cardiopulmonary function (echocardiographic and spirometry parameters) and patient-reported severity of symptoms (fatigue, dyspnea, health-related quality of life, anxiety, and depression). Age, body mass index, sex, number of comorbidities and duration of symptoms were included as potential confounders. Results showed that greater physical fitness and cardiopulmonary function were associated with lower severity of symptoms in people with post-COVID-19 condition. Cardiorespiratory fitness, lower-limb muscle strength, maximal voluntary ventilation and left ventricular ejection fraction account for reducing fatigue and dyspnea. Greater physical activity levels were associated with fewer symptoms and less-severe fatigue and dyspnea. In conclusion, preserving better cardiopulmonary health and physical condition during the course of the disease-even in mild cases-was related to a lower intensity of symptoms in non-hospitalized people with post-COVID-19 condition. It is probable that exercise and physical conditioning are valuable pre- and post-COVID-19 countermeasures that could help decrease the severity, not only of acute infection, but of post-COVID-19 persistent symptoms and prognosis.

Oxygen uptake kinetics and chronotropic responses to exercise are impaired in survivors of severe COVID-19

The post-acute phase of coronavirus disease 2019 (COVID-19) is often marked by several persistent symptoms and exertional intolerance, which compromise survivors’ exercise capacity. This was a cross-sectional study aiming to investigate the impact of COVID-19 on oxygen uptake (V̇o₂) kinetics and cardiopulmonary function in survivors of severe COVID-19 about 3–6 mo after intensive care unit (ICU) hospitalization. Thirty-five COVID-19 survivors previously admitted to ICU (5 ± 1 mo after hospital discharge) and 18 controls matched for sex, age, comorbidities, and physical activity level with no prior history of SARS-CoV-2 infection were recruited. Subjects were submitted to a maximum-graded cardiopulmonary exercise test (CPX) with an initial 3-min period of a constant, moderate-intensity walk (i.e., below ventilatory threshold, VT). V̇o₂ kinetics was remarkably impaired in COVID-19 survivors as evidenced at the on-transient by an 85% (P = 0.008) and 28% (P = 0.001) greater oxygen deficit and mean response time (MRT), respectively. Furthermore, COVID-19 survivors showed an 11% longer (P = 0.046) half-time of recovery of V̇o₂ (T_1/2V̇o₂) at the off-transient. CPX also revealed cardiopulmonary impairments following COVID-19. Peak oxygen uptake (V̇o_2peak), percent-predicted V̇o_2peak, and V̇o₂ at the ventilatory threshold (V̇o_2VT) were reduced by 17%, 17%, and 12% in COVID-19 survivors, respectively (all P < 0.05). None of the ventilatory parameters differed between groups (all P > 0.05). In addition, COVID-19 survivors also presented with blunted chronotropic responses (i.e., chronotropic index, maximum heart rate, and heart rate recovery; all P < 0.05). These findings suggest that COVID-19 negatively affects central (chronotropic) and peripheral (metabolic) factors that impair the rate at which V̇o₂ is adjusted to changes in energy demands.

NEW & NOTEWORTHY Our findings provide novel data regarding the impact of COVID-19 on submaximal and maximal cardiopulmonary responses to exercise. We showed that V̇o₂ kinetics is significantly impaired at both the onset (on-transient) and the recovery phase (off-transient) of exercise in these patients. Furthermore, our results suggest that survivors of severe COVID-19 may have a higher metabolic demand at a walking pace. These findings may partly explain the exertional intolerance frequently observed following COVID-19.

Prevention of Loss of Muscle Mass and Function in Older Adults during COVID-19 Lockdown: Potential Role of Dietary Essential Amino Acids

As the COVID-19 pandemic became a global emergency, social distancing, quarantine, and limitations in outdoor activities have resulted in an environment of enforced physical inactivity (EPI). A prolonged period of EPI in older individuals accelerates the deterioration of skeletal muscle health, including loss of muscle mass and function, commonly referred to as sarcopenia. Sarcopenia is associated with an increased likelihood of the progression of diabetes, obesity, and/or depression. Well-known approaches to mitigate the symptoms of sarcopenia include participation in resistance exercise training and/or intake of balanced essential amino acids (EAAs) and high-quality (i.e., containing high EEAs) protein. As the pandemic situation discourages physical exercise, nutritional approaches, especially dietary EAA intake, could be a good alternative for counteracting against EPI-promoted loss of muscle mass and function. Therefore, in the present review, we cover (1) the impact of EPI-induced muscle loss and function on health, (2) the therapeutic potential of dietary EAAs for muscle health (e.g., muscle mass and function) in the EPI condition in comparison with protein sources, and finally (3) practical guidelines of dietary EAA intake for optimal anabolic response in EPI.

Cardiopulmonary exercise testing to evaluate post-acute sequelae of COVID-19 ("Long COVID"): a systematic review and meta-analysis

IMPORTANCE

Reduced exercise capacity is commonly reported among individuals with Long COVID (LC). Cardiopulmonary exercise testing (CPET) is the gold-standard to measure exercise capacity to identify causes of exertional intolerance.

OBJECTIVES

To estimate the effect of SARS-CoV-2 infection on exercise capacity including those with and without LC symptoms and to characterize physiologic patterns of limitations to elucidate possible mechanisms of LC.

DATA SOURCES

We searched PubMed, EMBASE, and Web of Science, preprint severs, conference abstracts, and cited references in December 2021 and again in May 2022.

STUDY SELECTION

We included studies of adults with SARS-CoV-2 infection at least three months prior that included CPET measured peak VO ₂ . 3,523 studies were screened independently by two blinded reviewers; 72 (2.2%) were selected for full-text review and 36 (1.2%) met the inclusion criteria; we identified 3 additional studies from preprint servers.

DATA EXTRACTION AND SYNTHESIS

Data extraction was done by two independent reviewers according to PRISMA guidelines. Data were pooled with random-effects models.

MAIN OUTCOMES AND MEASURES

A priori primary outcomes were differences in peak VO ₂ (in ml/kg/min) among those with and without SARS-CoV-2 infection and LC.

RESULTS

We identified 39 studies that performed CPET on 2,209 individuals 3-18 months after SARS-CoV-2 infection, including 944 individuals with LC symptoms and 246 SARS-CoV-2 uninfected controls. Most were case-series of individuals with LC or post-hospitalization cohorts. By meta-analysis of 9 studies including 404 infected individuals, peak VO ₂ was 7.4 ml/kg/min (95%CI 3.7 to 11.0) lower among infected versus uninfected individuals. A high degree of heterogeneity was attributable to patient and control selection, and these studies mostly included previously hospitalized, persistently symptomatic individuals. Based on meta-analysis of 9 studies with 464 individuals with LC, peak VO ₂ was 4.9 ml/kg/min (95%CI 3.4 to 6.4) lower compared to those without symptoms. Deconditioning was common, but dysfunctional breathing, chronotropic incompetence, and abnormal oxygen extraction were also described.

CONCLUSIONS AND RELEVANCE

These studies suggest that exercise capacity is reduced after SARS-CoV-2 infection especially among those hospitalized for acute COVID-19 and individuals with LC. Mechanisms for exertional intolerance besides deconditioning may be multifactorial or related to underlying autonomic dysfunction.

Resistance Training before, during, and after COVID-19 Infection: What Have We Learned So Far?

At the end of 2019, a severe acute respiratory syndrome caused by SARS-CoV-2 started a pandemic, leading to millions of deaths and many important political and social changes. Even in the absence of contamination, the mobility reduction, social distancing and closing of exercise facilities negatively affected physical activity and conditioning, which is associated with muscle atrophy, loss of muscle strength, and reductions in functional capacity. In cases of infection, it has been shown that increased physical capacity is associated with decreased hospitalization and mortality risk. Although millions of people have died from COVID-19, most contaminated individuals survived the infection, but carried different sequelae, such as the severe loss of physical function and a reduced quality of life. Among different physical exercise models that might help to prevent and treat COVID-19-related conditions, resistance training (RT) might be particularly relevant. Among its benefits, RT can be adapted to be performed in many different situations, even with limited space and equipment, and is easily adapted to an individual's characteristics and health status. The current narrative review aims to provide insights into how RT can be used in different scenarios to counteract the negative effects of COVID-19. By doing this, the authors expect to provide insights to help deal with the current pandemic and similar events the world may face in the future.

Skeletal muscle alterations in patients with acute Covid-19 and post-acute sequelae of Covid-19

Skeletal muscle-related symptoms are common in both acute coronavirus disease (Covid)-19 and post-acute sequelae of Covid-19 (PASC). In this narrative review, we discuss cellular and molecular pathways that are affected and consider these in regard to skeletal muscle involvement in other conditions, such as acute respiratory distress syndrome, critical illness myopathy, and post-viral fatigue syndrome. Patients with severe Covid-19 and PASC suffer from skeletal muscle weakness and exercise intolerance. Histological sections present muscle fibre atrophy, metabolic alterations, and immune cell infiltration. Contributing factors to weakness and fatigue in patients with severe Covid-19 include systemic inflammation, disuse, hypoxaemia, and malnutrition. These factors also contribute to post-intensive care unit (ICU) syndrome and ICU-acquired weakness and likely explain a substantial part of Covid-19-acquired weakness. The skeletal muscle weakness and exercise intolerance associated with PASC are more obscure. Direct severe acute respiratory syndrome coronavirus (SARS-CoV)-2 viral infiltration into skeletal muscle or an aberrant immune system likely contribute. Similarities between skeletal muscle alterations in PASC and chronic fatigue syndrome deserve further study. Both SARS-CoV-2-specific factors and generic consequences of acute disease likely underlie the observed skeletal muscle alterations in both acute Covid-19 and PASC.

From heart to muscle: Pathophysiological mechanisms underlying long-term physical sequelae from SARS-CoV-2 infection

The long-term sequelae of the coronavirus disease 2019 (COVID-19) are multifaceted and, besides the lungs, impact other organs and tissues, even in cases of mild infection. Along with commonly reported symptoms such as fatigue and dyspnea, a significant proportion of those with prior COVID-19 infection also exhibit signs of cardiac damage, muscle weakness, and ultimately, poor exercise tolerance. This review provides an overview of evidence indicating cardiac impairments and persistent endothelial dysfunction in the peripheral vasculature of those previously infected with COVID-19, irrespective of the severity of the acute phase of illness. In addition, V̇o_2peak appears to be lower in convalescent patients, which may stem, in part, from alterations in O₂ transport such as impaired diffusional O₂ conductance. Together, the persistent multi-organ dysfunction induced by COVID-19 may set previously healthy individuals on a trajectory towards frailty and disease. Given the large proportion of individuals recovering from COVID-19, it is critically important to better understand the physical sequelae of COVID-19, the underlying biological mechanisms contributing to these outcomes, and the long-term effects on future disease risk. This review highlights relevant literature on the pathophysiology post-COVID-19 infection, gaps in the literature, and emphasizes the need for the development of evidence-based rehabilitation guidelines.

Longitudinal Smartphone-Based Post-hospitalisation Symptom Monitoring in SARS-CoV-2 Associated Respiratory Failure: A Multi-Centre Observational Study

Background: We aimed to longitudinally monitor the recovery in breathlessness, symptom burden, health-related quality-of-life, and mental health status in individuals hospitalised due to SARS-CoV-2 associated respiratory failure.

Methods: Individuals hospitalised due to SARS-CoV-2 associated respiratory failure were recruited at hospital discharge in three participating centres. During the 90 day follow-up, European Quality of Life−5 Dimensions−5 Levels Instrument (EQ-5D-5L), modified Medical Research Council (mMRC) Dyspnoea Scale, COPD Assessment Test (CAT), and weekly Hospital Anxiety and Depression Scale (HADS) questionnaires were assessed using a smartphone application. The results were presented using descriptive statistics and graphics. Linear mixed models with random intercept were fitted to analyse differences of intensive-care unit status on the recovery course in each outcome.

Results: We included 58 participants, 40 completed the study. From hospital discharge until 90 days post-discharge, EQ-5D-5L index changed from 0.83 (0.66, 0.92) to 0.96 (0.82, 1.0), VAS rating on general health status changed from 62 (50, 75) % to 80 (74, 94) %, CAT changed from 13 (10, 21) to 7 (3, 11) points, mMRC changed from 1 (0, 2) to 0 (0, 1) points, HADS depression subscale changed from 6 (4, 9) to 5 (1, 6) points, HADS anxiety subscale changed from 7 (3, 9) to 2 (1, 8) points. Differences in the recovery courses were observed between intensive-care and ward participants. Participants that were admitted to an intensive-care unit during their hospitalisation (n = 16) showed increases in CAT, mMRC, HADS scores, and decreases in EQ-5D-5L 30 days after hospital discharge.

Conclusion: Being admitted to an ICU led to statistically significant reductions in recovery in the EQ-5D-5L and the CAT. Furthermore, the flare-up in symptom burden and depression scores, accompanied by an attenuated recovery in HrQoL and general health status in the ICU-group suggests that a clinical follow-up 1 month after hospital discharge can be recommended, evaluating further treatments.

Clinical Trial Registration: [www.ClinicalTrials.gov], identifier [NCT04365595].

Phenotyping long COVID

The public health consequences of the epidemic of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infections may well go beyond the current burden on hospital services and the indirect effects of social distancing and lockdowns. Patients, particularly older ones with comorbidities, experience persistent dyspnoea, fatigue, body aches and brain fog for months after the acute phase of coronavirus disease 2019 (COVID-19) [1]. Post-acute sequelae of SARS-CoV-2 infection, more commonly called “long COVID”, attract considerable media attention, patient advocacy group-initiated research and, recently, USD 1.15 billion of funding by the US National Institutes of Health (NIH) [1]. Cellular damage, inflammatory cytokine production and pro-coagulant state induced by SARS-CoV-2 infection provide a pathophysiological rationale for long-lasting symptomatology [2]. Given the magnitude of the COVID-19 pandemic, with currently over 150 million reported cases, long COVID may emerge as a huge worldwide medical problem [1, 2].

Patients who recover from an acute SARS-CoV-2 infection often present with persistent symptoms lasting for months. The cardiopulmonary exercise test profile of those with “long COVID” is suggestive of deconditioning with a tendency to hyperventilation.https://bit.ly/3y8n0Bt