2024
The metabolic and physiologic impairments underlying long COVID associated exercise intolerance
Leitner B, Joseph P, Quast A, Ramirez M, Heerdt P, Villalobos J, Singh I. The metabolic and physiologic impairments underlying long COVID associated exercise intolerance. Pulmonary Circulation 2024, 14: e70009. PMID: 39544193, PMCID: PMC11560803, DOI: 10.1002/pul2.70009.Peer-Reviewed Original ResearchPeak VO<sub>2</sub>Long COVID patientsCOVID patientsReduced peak VOSeverity of SARS-CoV-2 infectionSystemic oxygen extractionSARS-CoV-2 infectionLong COVIDArterial blood samplesQuantitative metabolomicsPeak VOVenous lactateCardiac outputImpaired mitochondrial ATP productionMild infectionExercise capacityPatientsMitochondrial ATP productionExercise intoleranceArteriovenous gradientBlood samplesOxygen extractionDependent mannerMetabolomicsPhysiological impairment
2023
Exercise Pathophysiology in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and Postacute Sequelae of SARS-CoV-2 More in Common Than Not?
Joseph P, Singh I, Oliveira R, Capone C, Mullen M, Cook D, Stovall M, Squires J, Madsen K, Waxman A, Systrom D. Exercise Pathophysiology in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and Postacute Sequelae of SARS-CoV-2 More in Common Than Not? CHEST Journal 2023, 164: 717-726. PMID: 37054777, PMCID: PMC10088277, DOI: 10.1016/j.chest.2023.03.049.Peer-Reviewed Original ResearchConceptsMyalgic encephalomyelitis/chronic fatigue syndromeME/CFSChronic fatigue syndromeSARS-CoV-2Fatigue syndromePostacute sequelaeCardiopulmonary exercise testingSystemic blood flowExercise pathophysiologyExertional intoleranceIntractable fatigueExercise testingAcute infectionPostexertional malaiseExercise intoleranceOrthostatic intoleranceVentilatory controlLong-term consequencesBlood flowClinical overlapSuch symptomsIntoleranceSequelaeCOVID-19Syndrome
2021
Persistent Exertional Intolerance After COVID-19 Insights From Invasive Cardiopulmonary Exercise Testing
Singh I, Joseph P, Heerdt PM, Cullinan M, Lutchmansingh DD, Gulati M, Possick JD, Systrom DM, Waxman AB. Persistent Exertional Intolerance After COVID-19 Insights From Invasive Cardiopulmonary Exercise Testing. CHEST Journal 2021, 161: 54-63. PMID: 34389297, PMCID: PMC8354807, DOI: 10.1016/j.chest.2021.08.010.Peer-Reviewed Original ResearchConceptsInvasive cardiopulmonary exercise testingCardiopulmonary exercise testingCardiopulmonary diseaseExercise testingControl participantsPeak VOExertional limitationCOVID-19Greater ventilatory inefficiencyPeak cardiac indexSex-matched control participantsCohort of patientsSystemic oxygen extractionDead space ventilationOnly mild symptomsExertional intoleranceCardiac indexPulmonary hemodynamicsAcute infectionVentilatory inefficiencyExercise intolerancePathophysiologic mechanismsMild symptomsHyperventilatory responseOxygen extraction
2020
Systemic vascular distensibility relates to exercise capacity in connective tissue disease
Singh I, Oliveira RKF, Naeije R, Oldham WM, Faria-Urbina M, Waxman AB, Systrom DM. Systemic vascular distensibility relates to exercise capacity in connective tissue disease. Rheumatology 2020, 60: 1429-1434. PMID: 33001175, DOI: 10.1093/rheumatology/keaa510.Peer-Reviewed Original ResearchConceptsCTD patientsSystemic oxygen extractionExercise capacityVascular distensibilityCardiopulmonary diseaseOxygen extractionDecreased exercise capacityStroke volume augmentationReduced exercise capacityCommon clinical manifestationsRadial arterial catheterConnective tissue diseaseAerobic exercise capacityPulmonary vascular distensibilityCardio-pulmonary diseasePressure-flow plotsPulmonary hypertensionCardiopulmonary exerciseHeart failureArterial catheterExercise intoleranceTissue diseaseClinical manifestationsNormal controlsPatients
2015
Exercise Intolerance in Pulmonary Hypertension
Singh I, Zappetti D. Exercise Intolerance in Pulmonary Hypertension. Clinical Pulmonary Medicine 2015, 22: 258-259. DOI: 10.1097/cpm.0000000000000122.Peer-Reviewed Original Research