Chamley RR; Radcliffe Department of Medicine, Oxford, UK; Academic Department of Military Rehabilitation, Loughborough, UK
Holland JL; Collins J; Pierce K; Watson WD; Green PG; O’Brien D; O’Sullivan O; Barker-Davies R; Ladlow P; Neubauer S; Bennett A; Nicol ED; Holdsworth DA; Rider OJ;

International journal of cardiology [Int J Cardiol] 2023 Nov 17, pp. 131594.
Date of Electronic Publication: 2023 Nov 17.

Background: Since the COVID-19 pandemic, post-COVID syndrome (persistent symptoms/complications lasting >12 weeks) continues to pose medical and economic challenges. In military personnel, where optimal fitness is crucial, prolonged limitations affecting their ability to perform duties has occupational and psychological implications, impacting deployability and retention. Research investigating post-COVID syndrome exercise capacity and cardiopulmonary effects in military personnel is limited.
Methods: UK military personnel were recruited from the Defence Medical Services COVID-19 Recovery Service. Participants were separated into healthy controls without prior SARS-CoV-2 infection (group one), and participants with prolonged symptoms (>12 weeks) after mild-moderate (community-treated) and severe (hospitalised) COVID-19 illness (group 2 and 3, respectively). Participants underwent cardiac magnetic resonance imaging (CMR) and spectroscopy, echocardiography, pulmonary function testing and cardiopulmonary exercise testing (CPET).
Results: 113 participants were recruited. When compared in ordered groups (one to three), CPET showed stepwise decreases in peak work, work at VT1 and VO ₂ max (all p < 0.01). There were stepwise decreases in FVC (p = 0.002), FEV ₁ (p = 0.005), TLC (p = 0.002), V _A (p < 0.001), and DLCO (p < 0.002), and a stepwise increase in A-a gradient (p < 0.001). CMR showed stepwise decreases in LV/RV volumes, stroke volumes and LV mass (LVEDVi/RVEDVi p < 0.001; LVSV p = 0.003; RVSV p = 0.001; LV mass index p = 0.049).
Conclusion: In an active military population, post-COVID syndrome is linked to subclinical changes in maximal exercise capacity. Alongside disease specific changes, many of these findings share the phenotype of deconditioning following prolonged illness or bedrest. Partitioning of the relative contribution of pathological changes from COVID-19 and deconditioning is challenging in post-COVID syndrome recovery.

Tsuda T; Nemours Cardiac Center, Nemours Children’s Health, Wilmington, DE, 19803, USA.
Davidow K; D’Aloisio G; Quillen J;

Cardio-oncology (London, England) [Cardiooncology] 2023 Nov 17; Vol. 9 (1), pp. 42.
Date of Electronic Publication: 2023 Nov 17.

Background: Asymptomatic childhood cancer survivors (CCS) frequently show decreased exercise performance. Poor exercise performance may indicate impaired future cardiovascular health.
Methods: Cardiopulmonary exercise testing (CPET) was performed in asymptomatic off-treatment CCS (age ≥ 10 years). Patients were divided into Normal and Poor performance groups by %predicted maximum VO2 at 80%. Both peak and submaximal CPET values were analyzed.
Results: Thirty-eight males (19 Normal, 19 Poor) and 40 females (18 Normal, 22 Poor) were studied. Total anthracycline dosage was comparable among 4 groups. The body mass index (BMI), although normal, and weight were significantly higher in Poor groups. Peak heart rate (HR) and peak respiratory exchange ratio (RER) were comparable in all four groups. Peak work rate (pWR)/kg, peak oxygen consumption (pVO2)/kg, peak oxygen pulse (pOP)/kg, and ventilatory anaerobic threshold (VAT)/kg were significantly lower, whereas heart rate (HR) increase by WR/kg (ΔHR/Δ[WR/kg] was significantly higher in Poor groups. Simultaneously plotting of weight & pVO2 and ΔHR/ΔWR & ΔVO2/ΔHR revealed a distinct difference between the Normal and Poor groups in both sexes, suggesting decreased skeletal muscle mass and decreased stroke volume reserve, respectively, in Poor CCS. The relationship between VAT and pVO2 was almost identical between the two groups in both sexes. Ventilatory efficiency was mildly diminished in the Poor groups.
Conclusions: Decreased skeletal muscle mass, decreased stroke volume reserve, and slightly decreased ventilatory efficiency characterize Poor CCS in both sexes. This unique combined CPET analysis provides useful clinical biomarkers to screen subclinical cardiovascular abnormality in CCS and identifies an area for improvement.

Orr WB; Division of Pediatric Cardiology, University School of Medicine, St. Louis, Missouri, USA.
Colombo JN; Roberts B; Avari Silva JN; Missouri, USA.; Balzer D; Shahanavaz S;

CJC pediatric and congenital heart disease [CJC Pediatr Congenit Heart Dis] 2022 Jun 17; Vol. 1 (4), pp. 193-197.
Date of Electronic Publication: 2022 Jun 17 (Print Publication: 2022).

Previous studies have used cardiopulmonary exercise test (CPET) data to objectively assess physiological changes in patients undergoing percutaneous pulmonary valve implantation. A retrospective review was performed to assess pre- and post-CPET data among patients undergoing Alterra Adaptive Prestent and SAPIEN 3 transcatheter heart valve (Alterra) placement. Of the 7 patients eligible for the study, 5 (71%) were male. The mean age was 22 years (range: 12-49 years). CPET data showed significant ( P  = 0.03) improvement in ventilatory efficiency (V _E /V _CO2 ) while only 2 (29%) patients had an improvement of percent predicted peak oxygen consumption (V _O2 ). These findings suggest favourable haemodynamic changes though further investigation is needed.

Mahendran AK; Department of Pediatrics,  University of Cincinnati College of Medicine, Cincinnati, Ohio, USA.
Katz D; Opotowsky AR; Lubert AM;

CJC pediatric and congenital heart disease [CJC Pediatr Congenit Heart Dis] 2023 Jan 14; Vol. 2 (3), pp. 112-123.
Date of Electronic Publication: 2023 Jan 14 (Print Publication: 2023).

The Fontan circulation, a surgical palliation for single-ventricle congenital heart disease, profoundly impacts the cardiopulmonary response to exercise. Reliant on passive pulmonary blood flow, the Fontan circulation has limited capacity to augment cardiac output as necessary to supply working muscles during exercise. Cardiopulmonary exercise testing (CPET) objectively assesses cardiorespiratory fitness and provides insight into the etiology of exercise intolerance. Furthermore, CPET variables, such as peak oxygen consumption and submaximal variables, have prognostic value and may be used as meaningful endpoints in research studies. CPET is also useful in clinical research applications to assess the effect of pharmacologic or other interventions. Medical therapies to improve exercise tolerance in individuals with a Fontan circulation, such as pulmonary vasodilators, may modestly improve peak oxygen consumption. Exercise training focused on aerobic fitness and lower extremity strength may have a more consistent and larger impact on these measures of aerobic fitness. CPET is a valuable diagnostic and prognostic tool for those with a Fontan circulation. Newer ancillary assessments, such as noninvasive peripheral venous pressure monitoring and cardiac output measurements, hold promise to provide a more nuanced insight into the underlying pathophysiology.

Mooren JM; Faculty of Health, University of Witten/Herdecke, 58455 Witten, Germany.;
Garbsch R; Schäfer H; Kotewitsch M; Waranski M; Teschler M; Schmitz B; Mooren FC;

Journal of clinical medicine [J Clin Med] 2023 Oct 25; Vol. 12 (21).
Date of Electronic Publication: 2023 Oct 25.

Introduction: Post-COVID-19 syndrome (PCS) is a multisystemic disorder marked by impaired physical performance as one lead symptom. Since it has been suggested that endurance training as part of medical rehabilitation may be effective in improving physical performance capacity in PCS, this study aimed to compare different modes of aerobic endurance training.
Methods: A total of 110 PCS patients (49.3 ± 11.8 years; 38% women; time after infection = 260.2 ± 127.5 days) underwent detailed clinical screening including symptom-limited cardiopulmonary exercise testing at admission and after 4-6 weeks of inpatient medical rehabilitation. Questionnaires were used to assess disease perception. Patients performed controlled isocaloric cycle ergometer training (3-5 sessions/week; 18 min) as either continuous training (CT) at 50% of maximal workload or as interval training (IT; load = 60%, relief = 30%). Outcomes of PCS patients were compared to coronary artery disease patients (CAD; n = 96) to evaluate overall training effectiveness.
Results: Training participation was comparable between the groups, with no indication of training-specific exercise-induced fatigue. Overall, PCS patients improved significantly by a mean of 6.8 ± 12.1% for W at VT1; 3.1 ± 10.0% for VO ₂ at VT1; 5.5 ± 14.7% for O ₂ pulse at VT1; 7.5 ± 15.0% for W at VO _2peak ; 2.7 ± 11.0% for VO _2peak and 4.6 ± 12.4% for O ₂ pulse at VO _2peak (all p < 0.05) with no significant differences between groups ( p > 0.05). Both groups showed reduced levels of fatigue, anxiety, and depression as well as improved quality of life and wellbeing (all p < 0.05). Compared to guideline-based cardiac rehabilitation, PCS patients showed a similar improvement in workload and oxygen uptake compared to CAD patients.
Conclusion: PCS patients benefit from aerobic endurance training performed as moderate continuous or interval training as part of a medical rehabilitation program in terms of improved physical exercise capacity and disease perception. The results for PCS patients are comparable to the guideline-based rehabilitation of CAD patients.

Huang SC; Department of Physical Medicine and Rehabilitation, New Taipei Municipal Tucheng Hospital,  Taiwan.;
Lee CH; Hsu CC; Chang SY; Chen YA; Chiu CH; Hsiao CC; Su HR; S

Frontiers in physiology [Front Physiol] 2023 Oct 25; Vol. 14, pp. 1253598.
Date of Electronic Publication: 2023 Oct 25 (Print Publication: 2023).

Introduction: The acquisition of blood lactate concentration (BLC) during exercise is beneficial for endurance training, yet a convenient method to measure it remains unavailable. BLC and electrocardiogram (ECG) both exhibit variations with changes in exercise intensity and duration. In this study, we hypothesized that BLC during exercise can be predicted using ECG data.
Methods: Thirty-one healthy participants underwent four cardiopulmonary exercise tests, including one incremental test and three constant work rate (CWR) tests at low, moderate, and high intensity. Venous blood samples were obtained immediately after each CWR test to measure BLC. A mathematical model was constructed using 31 trios of CWR tests, which utilized a residual network combined with long short-term memory to analyze every beat of lead II ECG waveform as 2D images. An artificial neural network was used to analyze variables such as the RR interval, age, sex, and body mass index.
Results: The standard deviation of the fitting error was 0.12 mmol/L for low and moderate intensities, and 0.19 mmol/L for high intensity. Weighting analysis demonstrated that ECG data, including every beat of ECG waveform and RR interval, contribute predominantly.
Conclusion: By employing 2D convolution and artificial neural network-based methods, BLC during exercise can be accurately estimated non-invasively using ECG data, which has potential applications in exercise training.
Competing Interests: Author H-RS are employed by Super Genius Aitak Co., LTD. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.