Physical inactivity and postural orthostatic tachycardia syndrome

Postural orthostatic tachycardia syndrome (POTS) is a cardiovascular disorder characterized by large increases in heart rate upon standing, as well as orthostatic and exercise intolerance. Cardiovascular deconditioning associated with physical inactivity is thought to contribute to the pathophysiology of POTS; however, quantitative comparisons of physical activity levels between individuals with POTS and healthy adults are lacking. Therefore, we investigated the physical activity levels of individuals with POTS compared to healthy control participants. We hypothesized that people with POTS would have lower physical activity levels and higher heart rates than healthy control participants. As part of an on-going study, 108 individuals with POTS (96 women, 6 men, 6 non-binary or other; age: 27±7 yr) and 18 healthy adults (17 women, 1 man; age: 26±5 yr) wore Fitbit activity monitors for up to two weeks to continuously monitor step counts and heart rate. Individuals with POTS (5326 ± 2579 steps) performed less (p < 0.001) steps per day than healthy controls (8359 ± 2799 steps), with 49% of the POTS cohort taking less than 5000 steps per day. The average time per day spent performing moderate-to-vigorous physical activity (i.e., activity > 3 estimated METs) in the POTS group (21 ± 22 min) was almost half of the healthy control group (39 ± 27 min). Despite doing less daily physical activity, individuals with POTS had higher heart rates than control participants during both waking (POTS: 88 ± 9 beats/min vs. control: 83 ± 5 beats/min, p = 0.031) and sleeping hours (POTS: 70 ± 8 beats/min vs. control: 65 ± 7 beats/min, p = 0.018), reflecting their deconditioned phenotype. Overall, our results demonstrate that individuals with POTS have lower physical activity levels than healthy age-matched adults, reinforcing that physical inactivity is an important factor to consider in the spiral decline of health and function associated with POTS; however, it remains to be determined whether physical inactivity is a primary driver of POTS or a secondary consequence of symptoms. Supported by National Institutes of Health (1R01HL166272) and Canadian Institutes of Health Research (MFE – 201021). This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.