Exercise in the postural XXXX .

@entity1 @entity64 @entity10409 @entity26 @entity591
@entity1 with the @entity10409 Syndrome (POTS) have orthostatic intolerance, as well as exercise intolerance. Peak @entity26 uptake (VO2peak) is generally lower in these @entity1 compared with healthy sedentary individuals, suggesting a lower physical fitness level. During acute exercise, POTS @entity1 have an excessive increase in heart rate and reduced @entity64 volume for each level of absolute workload; however, when expressed at relative workload (%VO2peak), there is no difference in the heart rate response between @entity1 and healthy individuals. The relationship between cardiac output and VO2 is similar between POTS @entity1 and healthy individuals. Short-term (i.e., 3months) exercise training increases cardiac size and mass, blood volume, and VO2peak in POTS @entity1 . Exercise performance is improved after training. Specifically, @entity64 volume is greater and heart rate is lower at any given VO2 during exercise after training versus before training. Peak heart rate is the same but peak @entity64 volume and cardiac output are greater after training. Heart rate recovery from peak exercise is significantly faster after training, indicating an improvement in autonomic circulatory control. These results suggest that @entity1 with POTS have no intrinsic abnormality of heart rate regulation during exercise. The @entity591 in POTS is due to a reduced @entity64 volume. Cardiac remodeling and blood volume expansion associated with exercise training increase physical fitness and improve exercise performance in these @entity1 .
