Cardiopulmonary, metabolic, and perceptual responses during exercise in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS): A Multi-site Clinical Assessment of ME/CFS (MCAM) sub-study

• Published in: PloS one 2022-01, Vol.17 (3), p.e0265315-e0265315
• Main Authors: Cook, Dane B, VanRiper, Stephanie, Dougherty, Ryan J, Lindheimer, Jacob B, Falvo, Michael J, Chen, Yang, Lin, Jin-Mann S, Unger, Elizabeth R
• Format: Article
• Language: English
• Subjects: Anaerobic threshold; Biology and Life Sciences; Cardiorespiratory fitness; Chronic fatigue syndrome; Clinics; Confidence intervals; Disease control; Disease prevention; Efficiency; Encephalomyelitis; Engineering and Technology; Exercise; Exercise Test; Fatigue; Fatigue Syndrome, Chronic; Fatigue tests; Gas exchange; Heart Rate; Hospitals; Humans; Illnesses; Kinesiology; Mechanical ventilation; Medicine; Medicine and Health Sciences; Metabolism; Oxygen Consumption - physiology; Pathogens; Pathology; Physical Exertion; Physical Fitness; Physical Sciences; Physical training; Physiology; Respiration; Subgroups; Tidal Volume; Ventilation; Veterans health care
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0265315

Cardiopulmonary exercise testing has demonstrated clinical utility in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). However, to what extent exercise responses are independent of, or confounded by, aerobic fitness remains unclear. To characterize and compare exercise responses in ME/CFS and controls with and without matching for aerobic fitness. As part of the Multi-site Clinical Assessment of ME/CFS (MCAM) study, 403 participants (n = 214 ME/CFS; n = 189 controls), across six ME/CFS clinics, completed ramped cycle ergometry to volitional exhaustion. Metabolic, heart rate (HR), and ratings of perceived exertion (RPE) were measured. Ventilatory equivalent ([Formula: see text], [Formula: see text]), metrics of ventilatory efficiency, and chronotropic incompetence (CI) were calculated. Exercise variables were compared using Hedges' g effect size with 95% confidence intervals. Differences in cardiopulmonary and perceptual features during exercise were analyzed using linear mixed effects models with repeated measures for relative exercise intensity (20-100% peak [Formula: see text]). Subgroup analyses were conducted for 198 participants (99 ME/CFS; 99 controls) matched for age (±5 years) and peak [Formula: see text] (~1 ml/kg/min-1). Ninety percent of tests (n = 194 ME/CFS, n = 169 controls) met standard criteria for peak effort. ME/CFS responses during exercise (20-100% peak [Formula: see text]) were significantly lower for ventilation, breathing frequency, HR, measures of efficiency, and CI and significantly higher for [Formula: see text], [Formula: see text] and RPE (p