Postural orthostatic tachycardia syndrome (POTS), the most common form of orthostatic
intolerance in young people, affects approximately 500,000 people in the United States …

Visual impairment intracranial pressure (VIIP) syndrome is considered an unexplained
major risk for future long-duration spaceflight. NASA recently redefined this syndrome as …

The American College of Cardiology (ACC) has a long history of developing documents (eg,
decision pathways, health policy statements, appropriate use criteria) to provide members …

Bed rest studies of the past 20 years are reviewed. Head-down bed rest (HDBR) has proved
its usefulness as a reliable simulation model for the most physiological effects of spaceflight …

Maximal oxygen uptake is a physiological characteristic bounded by the parametric limits of
the Fick equation:(left ventricular (LV) end‐diastolic volume− LV end‐systolic volume)× heart …

Postural tachycardia syndrome (POTS) is a heterogeneous clinical syndrome that has
gained increasing interest over the past few decades due to its increasing prevalence and …

Cardiac muscle adapts well to changes in loading conditions. For example, left ventricular
(LV) hypertrophy may be induced physiologically (via exercise training) or pathologically …

The purpose of this perspective is to present a general theory—the Physical Stress Theory
(PST). The basic premise of the PST is that changes in the relative level of physical stress …

Background—Left ventricular compliance appears to decrease with aging, which may
contribute to the high incidence of heart failure in the elderly. However, whether this change …

Orthostatic intolerance (OI), having difficulty tolerating an upright posture because of
symptoms or signs that abate when returned to supine, is common in pediatrics. ‍ For …