POTS versus deconditioning: the same or different?

The 2007 Streeten Lecture focused on the idea that physical deconditioning plays a key role in the symptomology and pathophysiology of POTS. Parallels were drawn between the physiological responses to orthostatic stress seen in POTS patients and the physiological responses seen in "normal" humans after prolonged periods of bedrest, deconditioning, or space flight. Additionally, the idea that endurance exercise training might ameliorate some of these symptoms was also advanced. Finally, potential parallels between POTS, chronic fatigue syndrome, and fibromyalgia were also drawn and the potential role of exercise training as a "therapeutic intervention" in all three conditions was raised. The conceptual model for the lecture was that after some "initiating event" chronic deconditioning plays a significant role in the pathophysiology of these conditions, and these physiological changes in conjunction with "somatic hypervigilence" explain many of the complaints that this diverse group of patients have. Additionally, the idea that systematic endurance exercise training might be helpful was advanced, and data supportive of this idea was reviewed. The main conclusion is that the medical community must retain their empathy for patients with unusual conditions but at the same time send a firm but empowering message about physical activity. As always, we must also ask what do the ideas about physical activity and inactivity and the conditions mentioned above not explain?