Tagashira S; Kurose S; Kimura Y;

Heart and vessels [Heart Vessels] 2021 Jan 23. Date of Electronic Publication: 2021 Jan 23.

Anaerobic threshold (AT) from cardiopulmonary exercise tests (CPX) is the standard for measuring exercise intensity among patients with cardiovascular disease in Japan. However, it remains controversial whether AT represents the safety limit for exercise intensity in patients with cardiovascular disease. The purpose of this study was to investigate cardiac rehabilitation (CR) efficacy and safety with exercise intensities above the AT and at a traditional AT in a randomized trial. The participants included 57 patients who were admitted to the outpatient CR unit with a diagnosis of acute myocardial infarction. The participants were randomly divided as follows: 25 patients in the AT group, who performed aerobic exercises with an intensity at the AT; and 32 patients in the “Over AT” group, who performed exercises at an intensity higher than the AT. The following components were measured: maximum oxygen uptake (peak VO ₂ ), oxygen uptake at the AT (AT VO ₂ ), increase in oxygen uptake during exercise (ΔVO ₂ /ΔWR) during the CPX, vascular endothelial function test (%FMD: the percentage of flow-mediated dilation), and isometric knee extension strength. The measurements were obtained at the start of the exercise therapy and after 2, 3, and 4 months. They were compared within and between groups, and the correlation between the rates of improvement was investigated. Peak VO ₂ , AT VO ₂ , ΔVO ₂ /ΔWR, and %FMD had significantly improved after 3 months in both groups. The isometric knee extension strength had improved in the “Over AT” group after 2 months. Interactions were observed with peak VO ₂ , ΔVO ₂ /ΔWR, and isometric knee extension strength. However, %FMD was not significantly different between the groups. In the “Over AT” group, the rate of improvement in peak VO ₂ was positively correlated with the improvement in the isometric knee extension strength (r = 0.61, p < 0.001), but not with %FMD. These data suggest that exercise at an intensity above the AT improved exercise tolerance faster than that at the AT, and this improvement rate was associated with changes in isometric knee extension strength.

Herrod PJJ; Blackwell JEM; Boereboom CL; Atherton PJ; Williams JP; Lund JN; Phillips BE;

Aging medicine (Milton (N.S.W)) [Aging Med (Milton)] 2020 Sep 17; Vol. 3 (4), pp. 245-251. Date of Electronic Publication: 2020 Sep 17 (Print Publication: 2020).

Objective: High-intensity interval training (HIIT) has been shown to be more effective than moderate continuous aerobic exercise for improving cardiorespiratory fitness (CRF) in a limited time frame. However, the length of time required for HIIT to elicit clinically significant improvements in the CRF of older adults is currently unknown. The aim of this study was to compare changes in the CRF of older adults completing identical HIIT protocols of varying durations.
Methods: Forty healthy, community-dwelling older adults completed a cardiopulmonary exercise test (CPET) before and after 2, 4, or 6 weeks of fully supervised HIIT on a cycle ergometer, or a no-intervention control period.
Results: Anaerobic threshold (AT) was increased only after 4 (+1.9 [SD 1.1] mL/kg/min) and 6 weeks (+1.9 [SD 1.8] mL/kg/min) of HIIT (both P  < 0.001), with 6-week HIIT required to elicit improvements in VO ₂ peak (+3.0 [SD 6] mL/kg/min; P  = 0.04). Exercise tolerance increased after 2 (+15 [SD 15] W), 4 (+17 [SD 11] W), and 6 weeks (+16 [SD 11] W) of HIIT (all P  < 0.001), with no difference in increase between the groups. There were no changes in any parameter in the control group.
Conclusion: Improvements in exercise tolerance from HIIT precede changes in CRF. Just 4 weeks of a well-tolerated, reduced-exertion HIIT protocol are required to produce significant changes in AT, with a further 2 weeks of training also eliciting improvements in VO ₂ peak.

Baumbach P; Schmidt-Winter C; Hoefer J; Derlien S; Best N; Herbsleb M; Coldewey SM;

Frontiers in medicine [Front Med (Lausanne)] 2020 Dec 21; Vol. 7, pp. 585462. Date of Electronic Publication: 2020 Dec 21 (Print Publication: 2020).

Background: Mitochondria are the key players in aerobic energy generation via oxidative phosphorylation. Consequently, mitochondrial function has implications on physical performance in health and disease ranging from high performance sports to critical illness. The protoporphyrin IX-triplet state lifetime technique (PpIX-TSLT) allows in vivo measurements of mitochondrial oxygen tension (mitoPO ₂ ). Hitherto, few data exist on the relation of mitochondrial oxygen metabolism and ergospirometry-derived variables during physical performance. This study investigates the association of mitochondrial oxygen metabolism with gas exchange and blood gas analysis variables assessed during cardiopulmonary exercise testing (CPET) in aerobic and anaerobic metabolic phases. Methods: Seventeen volunteers underwent an exhaustive CPET (graded multistage protocol, 50 W/5 min increase), of which 14 were included in the analysis. At baseline and for every load level PpIX-TSLT-derived mitoPO ₂ measurements were performed every 10 s with 1 intermediate dynamic measurement to obtain mitochondrial oxygen consumption and delivery (mito V . O ₂ , mito D . O ₂ ). In addition, variables of gas exchange and capillary blood gas analyses were obtained to determine ventilatory and lactate thresholds (VT, LT). Metabolic phases were defined in relation to VT1 and VT2 (aerobic: <VT1, aerobic-anaerobic transition: ≥VT1 and <VT2 and anaerobic: ≥VT2). We used linear mixed models to compare variables of PpIX-TSLT between metabolic phases and to analyze their associations with variables of gas exchange and capillary blood gas analyses.
Results: MitoPO ₂ increased from the aerobic to the aerobic-anaerobic phase followed by a subsequent decline. A mitoPO ₂ peak, termed mitochondrial threshold (MT), was observed in most subjects close to LT2. Mito D . O ₂ increased during CPET, while no changes in mito V . O ₂ were observed. MitoPO ₂ was negatively associated with partial pressure of end-tidal oxygen and capillary partial pressure of oxygen and positively associated with partial pressure of end-tidal carbon dioxide and capillary partial pressure of carbon dioxide. Mito D . O ₂ was associated with cardiovascular variables. We found no consistent association for mito V . O ₂ .
Conclusion: Our results indicate an association between pulmonary respiration and cutaneous mitoPO ₂ during physical exercise. The observed mitochondrial threshold, coinciding with the metabolic transition from an aerobic to an anaerobic state, might be of importance in critical care as well as in sports medicine.

Dayton JD; Ford K; Carroll SJ; Flynn PA; Kourtidou S; Holzer RJ;

Pediatric cardiology [Pediatr Cardiol] 2021 Jan 04. Date of Electronic Publication: 2021 Jan 04.

The COVID-19 pandemic has had devastating direct consequences on the health of affected patients. It has also had a significant impact on the ability of unaffected children to be physically active. We evaluated the effect of deconditioning from social distancing and school shutdowns implemented during the COVID-19 pandemic on the cardiovascular fitness of healthy unaffected children. This is a single-center, retrospective case-control study performed in an urban tertiary referral center. A cohort of 10 healthy children that underwent cardiopulmonary exercise testing after COVID-19 hospital restrictions were lifted was compared to a matched cohort before COVID-19-related shutdowns on school and after-school activities. Comparisons of oxygen uptake (VO ₂ ) max and VO ₂ at anaerobic threshold between the pre- and post-COVID-19 cohorts were done. The VO ₂ max in the post-COVID cohort was significantly lower than in the pre-COVID cohort (39.1 vs. 44.7, p = 0.031). Only one out of ten patients had a higher VO ₂ max when compared to their matched pre-COVID control and was also the only patient with a documented history of participation in varsity-type athletics. The percentile of predicted VO ₂ was significantly lower in the post-COVID cohort (95% vs. 105%, p = 0.042). This study for the first time documented a significant measurable decline in physical fitness of healthy children as a result of the COVID-19 pandemic and its associated restrictions. Measures need to be identified that encourage and facilitate regular exercise in children in a way that are not solely dependent on school and organized after-school activities.

Laveneziana P; Di Paolo M; Palange P;

European respiratory review : an official journal of the European Respiratory Society [Eur Respir Rev] 2021 Jan 06; Vol. 30 (159). Date of Electronic Publication: 2021 Jan 06 (Print Publication: 2021).

Cardiopulmonary exercise testing (CPET) has long been used as diagnostic tool for cardiac diseases. During recent years CPET has been proven to be additionally useful for 1) distinguishing between normal and abnormal responses to exercise; 2) determining peak oxygen uptake and level of disability; 3) identifying factors contributing to dyspnoea and exercise limitation; 4) differentiating between ventilatory (respiratory mechanics and pulmonary gas exchange), cardiovascular, metabolic and peripheral muscle causes of exercise intolerance; 5) identifying anomalies of ventilatory (respiratory mechanics and pulmonary gas exchange), cardiovascular and metabolic systems, as well as peripheral muscle and psychological disorders; 6) screening for coexistent ischaemic heart disease, peripheral vascular disease and arterial hypoxaemia; 7) assisting in planning individualised exercise training; 8) generating prognostic information; and 9) objectively evaluating the impact of therapeutic interventions. As such, CPET is an essential part of patients’ clinical assessment. This article belongs to the special series on the “Ventilatory efficiency and its clinical prognostic value in cardiorespiratory disorders”, addressed to clinicians, physiologists and researchers, and aims at encouraging them to get acquainted with CPET in order to help and orient the clinical decision concerning individual patients.

Delsart P, Delahaye C, Devos P, Domanski O, Azzaoui R, Sobocinski J, Juthier F(, Vincentelli A, Rousse N, Mugnier A, Soquet J, Loobuyck V, Koussa M, Modine T, Jegou B, Bical A, Hysi I, Fabre O, Pontana F, Matran R, Mounier-Vehier C, Montaigne D.

Clin Cardiol. 2020 Dec 31. doi: 10.1002/clc.23537. Online ahead of print.

BACKGROUND: Although recommendations encourage daily moderate activities in post aortic dissection, very little data exists regarding cardiopulmonary exercise testing (CPET) to personalize those patient’s physical rehabilitation and assess their cardiovascular prognosis. DESIGN: We aimed at testing the prognostic insight of CPET regarding aortic and cardiovascular events by exploring a prospective cohort of patients followed-up after acute aortic dissection. METHODS: Patients referred to our department after an acute (type A or B) aortic dissection were prospectively included in a cohort between September 2012 and October 2017. CPET was performed once optimal blood pressure control was obtained. Clinical follow-up was done after CPET for new aortic event and major cardio-vascular events (MCE) not directly related to the aorta.
RESULTS: Among the 165 patients who underwent CPET, no adverse event was observed during exercise testing. Peak oxygen pulse was 1.46(1.22-1.84) mlO2/beat, that is, 97 (83-113) % of its predicted value, suggesting cardiac exercise limitation in a population under beta blockers (92% of the population). During a follow-up of 39(20-51) months from CPET, 42 aortic event recurrences and 22 MCE not related to aorta occurred. Low peak oxygen pulse (<85% of predicted value) was independently predictive of aortic event recurrence, while low peak oxygen uptake (<70% of predicted value) was an independent predictor of MCE occurrence.
CONCLUSION: CPET is safe in postaortic dissection patients should be used to not only to personalize exercise rehabilitation, but also to identify those patients with the highest risk for new aortic events and MCE not directly related to aorta.

SIRICHANA, W; NEUFELD,  V.; WANG, XI; HU,  B.; DOLEZAL, A.; COOPER,  B;

Medicine & Science in Sports & Exercise: December 2020 – Volume 52 – Issue 12 – p 2515-2521

Elliott AD; Verdicchio CV; Gallagher C; Linz D; Mahajan R; Mishima R; Kadhim K; Emami M; Middeldorp ME; Hendriks JM; Lau DH; Sanders P;

Heart, lung & circulation [Heart Lung Circ] 2020 Dec 16. Date of Electronic Publication: 2020 Dec 16.

Background: Reduced exercise capacity and exercise intolerance are commonly reported by individuals with atrial fibrillation (AF). Our objectives were to evaluate the contributing factors to reduced exercise capacity and describe the association between subjective measures of exercise intolerance versus objective measures of exercise capacity.
Methods: Two hundred and three (203) patients with non-permanent AF and preserved ejection fraction undergoing cardiopulmonary exercise testing (CPET) were recruited. Clinical characteristics, AF-symptom evaluation, and transthoracic echocardiography measures were collected. Peak oxygen consumption (VO_2peak ) was calculated during CPET as an objective measure of exercise capacity. We assessed the impact of 16 pre-defined clinical features, comorbidities and cardiac functional parameters on VO_2peak .
Results: Across this cohort (Age 66±11 years, 40.4% female and 32% in AF), the mean VO_2peak was 20.3±6.3 ml/kg/min. 24.9% of patients had a VO_2peak considered low (<16 ml/kg/min). In multivariable analysis, echocardiography-derived estimates of elevated left ventricular (LV) filling pressure (E/E’) and reduced chronotropic index were significantly associated with lower VO_2peak . The presence of AF at the time of testing was not significantly associated with VO_2peak but was associated with elevated minute ventilation to carbon dioxide production indicating impaired ventilatory efficiency. There was a poor association between VO_2peak and subjectively reported exercise intolerance and exertional dyspnoea.
Conclusion: Reduced exercise capacity in AF patients is associated with elevated LV filling pressure and reduced chronotropic response rather than rhythm status. Subjectively reported exercise intolerance is not a sensitive assessment of reduced exercise capacity. These findings have important implications for understanding reduced exercise capacity amongst AF patients and the approach to management in this cohort.

Lee CHA; Ismail H; Ho KM; Riedel B; Schier R;

British journal of anaesthesia [Br J Anaesth] 2020 Dec 16. Date of Electronic Publication: 2020 Dec 16.

NO ABSTRACT AVAILABLE