Abstract
BackgroundExercise capacity is evaluated using the 6-minute walk test in various diseases. Variety in the distances walked was also shown in healthy subjects. Moreover, age-related influences on cardiac hemodynamic response to the 6-minute walk test have not been clarified. The purpose of this study was thus to investigate the hemodynamic response to the 6-minute walk test and to detect factors related to the distance walked in healthy subjects.MethodsThirteen young adults (age 20.5 ± 0.7 years, BMI 22.0 ± 4.3) and 26 elderly individuals (age 60.2 ± 6.1 years, BMI 21.7 ± 2.2) were enrolled to measure real-time hemodynamic responses using non-invasive impedance cardiography during the 6-minute walk test.ResultsStroke volume was higher in the young than in the elderly and reached a plateau within 30 s of starting to walk in all subjects. An increase in heart rate took more than 1 min in the elderly, while it took less than 30 s in the young, which resulted in slower increases in cardiac output and cardiac index in the elderly. There was no difference in the distance in the 6-minute walk test between the young and the elderly. The distance walked was correlated with heart rate, cardiac output, and cardiac index, but not with stroke volume, at the end of the 6-minute walk test.ConclusionsThe distance walked appeared to depend on increased cardiac output based on heart rate, but did not appear to be limited by stroke volume, in healthy subjects.
Highlights
Exercise capacity is evaluated using the 6-minute walk test in various diseases
The distance walked did not show a significant difference in terms of age, whereas exercise intensity of the 6-minute walk test (6MWT) was significantly higher in the elderly than in the young (p = 0.001)
The distance walked during the 6MWT appeared to depend on the obtained cardiac output based on heart rate or exercise intensity, but not on age, in the present study
Summary
Exercise capacity is evaluated using the 6-minute walk test in various diseases. Variety in the distances walked was shown in healthy subjects. Age-related influences on cardiac hemodynamic response to the 6-minute walk test have not been clarified. The purpose of this study was to investigate the hemodynamic response to the 6-minute walk test and to detect factors related to the distance walked in healthy subjects. Exercise capacity has predominantly been evaluated by cardiopulmonary exercise or the 6-minute walk test (6MWT). Geographic variations in the distances walked were noted in healthy adults and a wide range of exercise intensities calculated by heart rate during the 6MWT were reported from 59 to 88 % as percentage of maximal heart rate [4], which made it difficult to apply predictive. A linear relationship between oxygen uptake and cardiac output or heart rate during cardiopulmonary exercise was shown, whereas maximal stroke volume was reached at submaximal intensities below the anaerobic threshold [9]. It is known that age is negatively associated with oxygen uptake, cardiac output, and heart rate at peak exercise [10, 11]
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