{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,6]],"date-time":"2026-10-06T01:11:58Z","timestamp":1791249118107,"version":"4.1.0"},"reference-count":40,"publisher":"Ovid Technologies (Wolters Kluwer Health)","issue":"9","content-domain":{"domain":["www.ahajournals.org"],"crossmark-restriction":true},"short-container-title":["JAHA"],"published-print":{"date-parts":[[2022,5,3]]},"abstract":"<jats:sec xml:lang=\"en\">\n                    <jats:title>Background<\/jats:title>\n                    <jats:p xml:lang=\"en\">Ongoing exercise intolerance of unclear cause following COVID\u201019 infection is well recognized but poorly understood. We investigated exercise capacity in patients previously hospitalized with COVID\u201019 with and without self\u2010reported exercise intolerance using magnetic resonance\u2013augmented cardiopulmonary exercise testing.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec xml:lang=\"en\">\n                    <jats:title>Methods and Results<\/jats:title>\n                    <jats:p xml:lang=\"en\">\n                      Sixty subjects were enrolled in this single\u2010center prospective observational case\u2010control study, split into 3 equally sized groups: 2 groups of age\u2010, sex\u2010, and comorbidity\u2010matched previously hospitalized patients following COVID\u201019 without clearly identifiable postviral complications and with either self\u2010reported reduced (COVID\n                      <jats:sub>reduced<\/jats:sub>\n                      ) or fully recovered (COVID\n                      <jats:sub>normal<\/jats:sub>\n                      ) exercise capacity; a group of age\u2010 and sex\u2010matched healthy controls. The COVID\n                      <jats:sub>reduced<\/jats:sub>\n                      group had the lowest peak workload (79W [Interquartile range (IQR), 65\u2013100] versus controls 104W [IQR, 86\u2013148];\n                      <jats:italic>P<\/jats:italic>\n                      =0.01) and shortest exercise duration (13.3\u00b12.8\u00a0minutes versus controls 16.6\u00b13.5\u00a0minutes;\n                      <jats:italic>P<\/jats:italic>\n                      =0.008), with no differences in these parameters between COVID\n                      <jats:sub>normal<\/jats:sub>\n                      patients and controls. The COVID\n                      <jats:sub>reduced<\/jats:sub>\n                      group had: (1) the lowest peak indexed oxygen uptake (14.9\u00a0mL\/minper kg [IQR, 13.1\u201316.2]) versus controls (22.3\u00a0mL\/min per kg [IQR, 16.9\u201327.6];\n                      <jats:italic>P<\/jats:italic>\n                      =0.003) and COVID\n                      <jats:sub>normal<\/jats:sub>\n                      patients (19.1\u00a0mL\/min per kg [IQR, 15.4\u201323.7];\n                      <jats:italic>P<\/jats:italic>\n                      =0.04); (2) the lowest peak indexed cardiac output (4.7\u00b11.2\u00a0L\/min per m\n                      <jats:sup>2<\/jats:sup>\n                      ) versus controls (6.0\u00b11.2\u00a0L\/min per m\n                      <jats:sup>2<\/jats:sup>\n                      ;\n                      <jats:italic>P<\/jats:italic>\n                      =0.004) and COVID\n                      <jats:sub>normal<\/jats:sub>\n                      patients (5.7\u00b11.5\u00a0L\/min per m\n                      <jats:sup>2<\/jats:sup>\n                      ;\n                      <jats:italic>P<\/jats:italic>\n                      =0.02), associated with lower indexed stroke volume (SVi:COVID\n                      <jats:sub>reduced<\/jats:sub>\n                      39\u00b110\u00a0mL\/min per m\n                      <jats:sup>2<\/jats:sup>\n                      versus COVID\n                      <jats:sub>normal<\/jats:sub>\n                      43\u00b17\u00a0mL\/min per m\n                      <jats:sup>2<\/jats:sup>\n                      versus controls 48\u00b110\u00a0mL\/min per m\n                      <jats:sup>2<\/jats:sup>\n                      ;\n                      <jats:italic>P<\/jats:italic>\n                      =0.02). There were no differences in peak tissue oxygen extraction or biventricular ejection fractions between groups. There were no associations between COVID\u201019 illness severity and peak magnetic resonance\u2013augmented cardiopulmonary exercise testing metrics. Peak indexed oxygen uptake, indexed cardiac output, and indexed stroke volume all correlated with duration from discharge to magnetic resonance\u2013augmented cardiopulmonary exercise testing (\n                      <jats:italic>P<\/jats:italic>\n                      &lt;0.05).\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec xml:lang=\"en\">\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p xml:lang=\"en\">Magnetic resonance\u2013augmented cardiopulmonary exercise testing suggests failure to augment stroke volume as a potential mechanism of exercise intolerance in previously hospitalized patients with COVID\u201019. This is unrelated to disease severity and, reassuringly, improves with time from acute illness.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1161\/jaha.121.024207","type":"journal-article","created":{"date-parts":[[2022,4,26]],"date-time":"2022-04-26T05:46:16Z","timestamp":1650951976000},"update-policy":"https:\/\/doi.org\/10.1161\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":30,"title":["Ongoing Exercise Intolerance Following COVID\u201019: A Magnetic Resonance\u2013Augmented Cardiopulmonary Exercise Test Study"],"prefix":"10.1161","volume":"11","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-1541-4081","authenticated-orcid":false,"given":"James T.","family":"Brown","sequence":"first","affiliation":[{"name":"National Pulmonary Hypertension Service Royal Free London NHS Foundation TrustLondon United Kingdom"},{"name":"UCL Department of Cardiac MRI University College London (Royal Free Campus) London United Kingdom"},{"name":"Institute of Cardiovascular 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