{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,31]],"date-time":"2026-03-31T13:00:09Z","timestamp":1774962009156,"version":"3.50.1"},"reference-count":15,"publisher":"Oxford University Press (OUP)","issue":"2","license":[{"start":{"date-parts":[[2026,3,31]],"date-time":"2026-03-31T00:00:00Z","timestamp":1774915200000},"content-version":"vor","delay-in-days":70,"URL":"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"}],"funder":[{"name":"Vifor Pharma Nederland BV"},{"DOI":"10.13039\/501100002996","name":"Dutch Heart Foundation","doi-asserted-by":"crossref","award":["CVON2017-21-SHE PREDICTS HF"],"award-info":[{"award-number":["CVON2017-21-SHE PREDICTS HF"]}],"id":[{"id":"10.13039\/501100002996","id-type":"DOI","asserted-by":"crossref"}]},{"DOI":"10.13039\/501100002996","name":"Dutch Heart Foundation","doi-asserted-by":"crossref","award":["CVON2015-10-Early"],"award-info":[{"award-number":["CVON2015-10-Early"]}],"id":[{"id":"10.13039\/501100002996","id-type":"DOI","asserted-by":"crossref"}]},{"name":"Senior Dekker Clinical Scientist Grant","award":["2019T064"],"award-info":[{"award-number":["2019T064"]}]},{"name":"UMCG\u2013Siemens for building the future of Health"},{"DOI":"10.13039\/100016244","name":"Health Foundation Limburg","doi-asserted-by":"publisher","id":[{"id":"10.13039\/100016244","id-type":"DOI","asserted-by":"publisher"}]},{"name":"J.A.L.J."},{"DOI":"10.13039\/501100012264","name":"NIH","doi-asserted-by":"publisher","award":["R01 HL173346"],"award-info":[{"award-number":["R01 HL173346"]}],"id":[{"id":"10.13039\/501100012264","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2026,3,3]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Background and Aims<\/jats:title>\n                    <jats:p>Patients with heart failure and preserved ejection fraction (HFpEF) experience significant exercise intolerance, yet its underlying mechanisms remain poorly defined and are multifactorial. Iron deficiency (ID) occurs frequently in HFpEF and may contribute to exercise impairment. This study evaluated mitochondrial oxidative muscle metabolism in HFpEF using in vivo \u00a031phosphorus magnetic resonance spectroscopy (31P-MRS) employing two exercise protocols, and assessed whether ID influences exercise energetics.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>In this parallel analysis of prospective studies at two sites, patients with HFpEF and control individuals performed either isometric exercise (isolated leg protocol) or dynamic exercise (cardiopulmonary protocol) with concomitant phosphocreatine recovery assessment using in vivo \u00a031P-MRS. Associations between clinical factors and oxidative metabolism were evaluated. ID was defined as ferritin &amp;lt;100\u2005\u00b5g\/L, or ferritin 100\u2013299\u2005\u00b5g\/L with transferrin saturation &amp;lt;20%.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>Fifty-eight patients with HFpEF and 16 controls performed isometric exercise (n = 46 HFpEF; n = 16 control) or cardiopulmonary exercise (n = 12 HFpEF). Phosphocreatine recovery halftime after isometric exercise was prolonged in patients versus controls [27 (23\u201332) vs 24 (19\u201328) seconds, respectively; P = .03]. Phosphocreatine recovery halftime after dynamic exercise in patients was 39 (27\u201357) seconds. Both cohorts consisted of patients with and without ID (n = 19 and 27, and n = 6 and 6, respectively), who had comparable exercise and oxidative muscle capacity (all P &amp;gt; .42). High-sensitive C-reactive protein was associated with prolonged phosphocreatine recovery halftime (P =. 01).<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>Patients with HFpEF exhibit impaired whole-muscle oxidative capacity of skeletal muscle, as shown by two different 31P-MRS protocols with upper leg measurements, independent of ID status.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Study registration<\/jats:title>\n                    <jats:p>NTR6605, NTR7297 (https:\/\/onderzoekmetmensen.nl\/nl\/trial\/55673); NCT05750940 (https:\/\/clinicaltrials.gov\/study\/NCT05750940).<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1093\/eschf\/xvaf035","type":"journal-article","created":{"date-parts":[[2026,1,6]],"date-time":"2026-01-06T12:31:13Z","timestamp":1767702673000},"source":"Crossref","is-referenced-by-count":0,"title":["Quantifying skeletal muscle energy metabolism during exercise in heart failure with preserved ejection fraction using\n                    <i>in vivo<\/i>\n                    \u00a031P magnetic resonance spectroscopy"],"prefix":"10.1093","volume":"13","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-9369-3453","authenticated-orcid":false,"given":"Jerremy","family":"Weerts","sequence":"first","affiliation":[{"name":"Department of Cardiology, CARIM School for Cardiovascular Diseases, Maastricht University Medical Centre (MUMC+) , Maastricht ,","place":["The Netherlands"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Suzanne N","family":"Voorrips","sequence":"additional","affiliation":[{"name":"Department of Cardiology, University of Groningen, Department of Cardiology, University Medical Center Groningen (UMCG) , Groningen ,","place":["The Netherlands"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jeroen A L","family":"Jeneson","sequence":"additional","affiliation":[{"name":"Cognitive Neuroscience Centre, University of Groningen, University Medical Center Groningen (UMCG) , Groningen ,","place":["The Netherlands"]},{"name":"Department of Radiology and Nuclear Medicine, Amsterdam University Medical Center (Site AMC) , Amsterdam ,","place":["The Netherlands"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Arantxa","family":"Barandiar\u00e1n Aizpurua","sequence":"additional","affiliation":[{"name":"Department of Cardiology, CARIM School for Cardiovascular Diseases, Maastricht University Medical Centre (MUMC+) , Maastricht ,","place":["The Netherlands"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Julian","family":"Mevenkamp","sequence":"additional","affiliation":[{"name":"Department of Radiology and Nuclear Medicine, Maastricht University Medical Centre (MUMC+) , Maastricht ,","place":["The Netherlands"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Anita J","family":"Sibeijn-Kuiper","sequence":"additional","affiliation":[{"name":"Cognitive Neuroscience Centre, University of Groningen, University Medical Center Groningen (UMCG) , Groningen ,","place":["The Netherlands"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Remco J","family":"Renken","sequence":"additional","affiliation":[{"name":"Cognitive Neuroscience Centre, University of Groningen, University Medical Center Groningen (UMCG) , Groningen ,","place":["The Netherlands"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Blanche L M","family":"Schroen","sequence":"additional","affiliation":[{"name":"Department of Cardiology, CARIM School for Cardiovascular Diseases, Maastricht University Medical Centre (MUMC+) , Maastricht ,","place":["The Netherlands"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5457-3010","authenticated-orcid":false,"given":"Christian","family":"Knackstedt","sequence":"additional","affiliation":[{"name":"Department of Cardiology, CARIM School for Cardiovascular Diseases, Maastricht University Medical Centre (MUMC+) , Maastricht ,","place":["The Netherlands"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Alfons J H M","family":"Houben","sequence":"additional","affiliation":[{"name":"Department of Internal Medicine, CARIM School for Cardiovascular Diseases, Maastricht University Medical Centre (MUMC+) , Maastricht ,","place":["The Netherlands"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9705-4413","authenticated-orcid":false,"given":"Peter","family":"Van der Meer","sequence":"additional","affiliation":[{"name":"Department of Cardiology, University of Groningen, Department of Cardiology, University Medical Center Groningen (UMCG) , Groningen ,","place":["The Netherlands"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Vera B","family":"Schrauwen-Hinderling","sequence":"additional","affiliation":[{"name":"Department of Radiology and Nuclear Medicine, Maastricht University Medical Centre (MUMC+) , Maastricht ,","place":["The Netherlands"]},{"name":"Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research at Heinrich Heine University D\u00fcsseldorf , D\u00fcsseldorf ,","place":["Germany"]},{"name":"German Center for Diabetes Research (DZD) , M\u00fcnchen-Neuherberg 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