Applied Physiology and Nutrition Research Group, School of Physical Education and Sport, School of Medicine, University of São Paulo, São Paulo, Brazil.
Rheumatology Division, Hospital das Clinicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.
Am J Physiol Heart Circ Physiol. 2022 Sep 1;323(3):H569-H576. doi: 10.1152/ajpheart.00291.2022. Epub 2022 Aug 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 (V̇o) 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). V̇o kinetics was remarkably impaired in COVID-19 survivors as evidenced at the on-transient by an 85% ( = 0.008) and 28% ( = 0.001) greater oxygen deficit and mean response time (MRT), respectively. Furthermore, COVID-19 survivors showed an 11% longer ( = 0.046) half-time of recovery of V̇o (TV̇o) at the off-transient. CPX also revealed cardiopulmonary impairments following COVID-19. Peak oxygen uptake (V̇o), percent-predicted V̇o, and V̇o at the ventilatory threshold (V̇o) were reduced by 17%, 17%, and 12% in COVID-19 survivors, respectively (all < 0.05). None of the ventilatory parameters differed between groups (all > 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 < 0.05). These findings suggest that COVID-19 negatively affects central (chronotropic) and peripheral (metabolic) factors that impair the rate at which V̇o is adjusted to changes in energy demands. Our findings provide novel data regarding the impact of COVID-19 on submaximal and maximal cardiopulmonary responses to exercise. We showed that V̇o 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.
新型冠状病毒疾病 2019（COVID-19）的康复后期通常伴有多种持续症状和运动不耐受，这会影响幸存者的运动能力。这是一项横断面研究，旨在调查 COVID-19 对重症 COVID-19 幸存者在 ICU 住院后约 3-6 个月时摄氧量（V̇o）动力学和心肺功能的影响。35 名以前因 COVID-19 入住 ICU（出院后 5±1 个月）的 COVID-19 幸存者和 18 名与性别、年龄、合并症和身体活动水平相匹配且没有 SARS-CoV-2 感染史的对照组被招募。受试者进行最大分级心肺运动测试（CPX），初始 3 分钟为恒定、中等强度步行（即低于通气阈，VT）。在发作时，COVID-19 幸存者的 V̇o 动力学明显受损，表现为氧亏和平均反应时间（MRT）分别增加 85%（ = 0.008）和 28%（ = 0.001）。此外，COVID-19 幸存者在发作后期 V̇o 的恢复半衰期（TV̇o）延长 11%（ = 0.046）。CPX 还显示 COVID-19 后心肺功能受损。峰值摄氧量（V̇o）、预测 V̇o 的百分比和 V̇o 在通气阈（V̇o）分别降低了 17%、17%和 12%在 COVID-19 幸存者中，均（所有 ＜0.05）。两组之间的通气参数均无差异（所有 ＞0.05）。此外，COVID-19 幸存者的变时反应也减弱（即变时指数、最大心率和心率恢复；所有 ＜0.05）。这些发现表明 COVID-19 对调节摄氧量以适应能量需求变化的中央（变时）和外周（代谢）因素产生负面影响。我们的研究结果提供了关于 COVID-19 对亚最大和最大心肺运动反应的影响的新数据。我们表明，在这些患者的运动开始时（发作时）和恢复阶段（发作后），V̇o 动力学均明显受损。此外，我们的结果表明，重症 COVID-19 的幸存者可能在步行时需要更高的代谢需求。这些发现可以部分解释 COVID-19 后经常观察到的运动不耐受。
