Betsy A. Keller, PhD, is a professor in the Department of Exercise & Sport Sciences at Ithaca College in New York. She is a fellow of the American College of Sports Medicine (ACSM), past member of the Board of Trustees of ACSM, and past president and former department chair of the Mid-Atlantic Regional Chapter of ACSM.
Since 2005, she has provided 2-day cardiopulmonary exercise testing (CPET) for persons with ME/CFS for purposes of research and/or to provide an objective assessment of functional capacity and ability to perform and recover following physical work for disability reports. She studies the effects of physical activity in ME/CFS on parameters of physiological and immune function.
In 2015 Keller said "Given what we have learned in the past eight years about this illness, it is intellectually embarrassing to suggest that ME is a psychological illness."
- 2016, A Pair of Identical Twins Discordant for Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Differ in Physiological Parameters and Gut Microbiome Composition
"BACKGROUND: Patients with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) present with profound fatigue, flu-like symptoms, pain, cognitive impairment, orthostatic intolerance, and post-exertional malaise (PEM), and exacerbation of some or all of the baseline symptoms. CASE REPORT: We report on a pair of 34-year-old monozygotic twins discordant for ME/CFS, with WELL, the non-affected twin, and ILL, the affected twin. Both twins performed a two-day cardiopulmonary exercise test (CPET), pre- and post-exercise blood samples were drawn, and both provided stool samples for biochemical and molecular analysis. At peak exertion for both CPETs, ILL presented lower VO2peak and peak workload compared to WELL. WELL demonstrated normal reproducibility of VO2@ventilatory/anaerobic threshold (VAT) during CPET2, whereas ILL experienced an abnormal reduction of 13% in VAT during CPET2. A normal rise in lactate dehydrogenase (LDH), creatine kinase (CK), adrenocorticotropic hormone (ACTH), cortisol, creatinine, and ferritin content was observed following exercise for both WELL and ILL at each CPET. ILL showed higher increases of resistin, soluble CD40 ligand (sCD40L), and soluble Fas ligand (sFasL) after exercise compared to WELL. The gut bacterial microbiome and virome were examined and revealed a lower microbial diversity in ILL compared to WELL, with fewer beneficial bacteria such as Faecalibacterium and Bifidobacterium, and an expansion of bacteriophages belonging to the tailed dsDNA Caudovirales order. CONCLUSIONS: Results suggest dysfunctional immune activation in ILL following exercise and that prokaryotic viruses may contribute to mucosal inflammation and bacterial dysbiosis. Therefore, a two-day CPET and molecular analysis of blood and microbiomes could provide valuable information about ME/CFS, particularly if applied to a larger cohort of monozygotic twins."
- 2014, Inability of myalgic encephalomyelitis/chronic fatigue syndrome patients to reproduce VO₂peak indicates functional impairment (FULL TEXT)]
Abstract - "Background: Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a multi-system illness characterized, in part, by increased fatigue following minimal exertion, cognitive impairment, poor recovery to physical and other stressors, in addition to other symptoms. Unlike healthy subjects and other diseased populations who reproduce objective physiological measures during repeat cardiopulmonary exercise tests (CPETs), ME/CFS patients have been reported to fail to reproduce results in a second CPET performed one day after an initial CPET. If confirmed, a disparity between a first and second CPET could serve to identify individuals with ME/CFS, would be able to document their extent of disability, and could also provide a physiological basis for prescribing physical activity as well as a metric of functional impairment. Methods: 22 subjects diagnosed with ME/CFS completed two repeat CPETs separated by 24 h. Measures of oxygen consumption (VO2), heart rate (HR), minute ventilation (Ve), workload (Work), and respiratory exchange ratio (RER) were made at maximal (peak) and ventilatory threshold (VT) intensities. Data were analyzed using ANOVA and Wilcoxon’s Signed-Rank Test (for RER). Results: ME/CFS patients showed significant decreases from CPET1 to CPET2 in VO2peak (13.8%), HRpeak (9 bpm), Ve peak (14.7%), and Work@peak (12.5%). Decreases in VT measures included VO2@VT (15.8%), Ve@VT (7.4%), and Work@VT (21.3%). Peak RER was high (≥1.1) and did not differ between tests, indicating maximum effort by participants during both CPETs. If data from only a single CPET test is used, a standard classification of functional impairment based on VO2peak or VO2@VT results in over-estimation of functional ability for 50% of ME/CFS participants in this study. Conclusion: ME/CFS participants were unable to reproduce most physiological measures at both maximal and ventilatory threshold intensities during a CPET performed 24 hours after a prior maximal exercise test. Our work confirms that repeated CPETs warrant consideration as a clinical indicator for diagnosing ME/CFS. Furthermore, if based on only one CPET, functional impairment classification will be mis-identified in many ME/CFS participants."
Talks & interviews
- 2016, 12th International IACFS/ME Biennial Clinical and Research Conference, Emerging Science and Clinical Care, How Cardiopulmonary Exercise Testing Informs Pathology and Treatment(Workshop given with Christopher Snell, Ph.D. and Mark VanNess, Ph.D.)
- 2013, ‘A Foreign and Illogical Result': Dr. Betsy Keller on Exercise Testing in Chronic Fatigue Syndrome (ME/CFS)
- Ithaca College - Betsy Keller
- 2014, NEW DIAGNOSTIC TOOLS FOR ME/CFS
- 2012, Exercise Testing and Using a Heart Rate Monitor
- Nice Guidelines Blog
- Giloteaux, Ludovic; Hanson, Maureen R.; Keller, Betsy (2016), "A Pair of Identical Twins Discordant for Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Differ in Physiological Parameters and Gut Microbiome Composition", American Journal of Case Reports, 17: 720-729, doi:10.12659/AJCR.900314
- Keller, Betsy A.; Pryor, John Luke; Giloteaux, Ludovic (2014), "Inability of myalgic encephalomyelitis/chronic fatigue syndrome patients to reproduce VO2peak indicates functional impairment", Journal of Translational Medicine, 12 (104), doi:10.1186/1479-5876-12-104