Hemodynamic Responses to Positional Change in Habitually Physically Active and Inactive Older Men

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Abstract
This study explored hemodynamic responses to positional change in 11 habitually physically active and 11 physically inactive healthy older men (mean age 70 years). Data were collected in the supine, sitting, standing, and 70.degree. upright tilt positions over a 10-minute period (long-term response). Dependent variables were heart rate, stroke volume, cardiac output, total peripheral resistance, and blood pressure. Stroke volume, cardiac output, and total peripheral resistance were expressed per unit body surface area. The results of this study indicated that the physically active older men had significantly lower resting heart rates and significantly higher stroke volume indicates in all four positions compared with the physically inactive men. The physically active men also tended to have lower total peripheral resistance indices and higher cardiac indices in all four positions, but the differences were not statistically significant. However, physically active and inactive older men reacted similarly (with respect to all hemodynamic variables except the stroke volume index) in the sitting, standing, and 70.degree. upright tilt positions as compared with the supine; the stroke volume index decreased significantly more compared with that of the supine in the physically active men.