In a nutshell: Chronotropic incompetence (CI) - the inability of the heart to keep pace with increased activity - is common in myalgic encephalomyelitis (ME/CFS)CI is worse in women with ME/CFS but both men and women have a lower than expected heart rate at the anaerobic thresholdCI is worse in those who have a more … Continue reading Blunted heart rate and implications for pacing in ME/CFS