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Hormonal responses in elders experiencing pre-syncopal symptoms during head-up tilt before and after exercise
J F Carroll1, C E Wood, M L Pollock
1Center for Exercise Science, College of Medicine, University of Florida, Gainesville, USA.
Summary
Endurance training improved head-up tilt test (HUT) tolerance in elderly individuals with pre-syncopal symptoms. Six months of exercise reduced vasopressin and plasma volume loss during HUT, indicating enhanced cardiovascular regulation.
Area of Science:
- Cardiology
- Gerontology
- Exercise Physiology
Background:
- Elderly individuals experiencing pre-syncopal symptoms during head-up tilt testing (HUT) exhibit distinct hormonal responses compared to asymptomatic individuals.
- These responses are assessed before and after a 6-month endurance training intervention.
Purpose of the Study:
- To compare hormonal responses and plasma volume changes during HUT in elderly symptomatic versus asymptomatic individuals.
- To evaluate the effects of 6 months of endurance training on HUT tolerance and associated physiological markers in symptomatic elderly individuals.
Main Methods:
- 35 men and women (61-79 years) were categorized into symptomatic and asymptomatic groups based on HUT responses.
- Hormonal levels (ACTH, vasopressin, aldosterone, norepinephrine, epinephrine), hemoglobin, and hematocrit were measured during supine rest and HUT.
- Plasma volume changes were calculated from hemoglobin and hematocrit variations; training involved treadmill walking or stair climbing 3x/week.
Main Results:
- Symptomatic subjects showed greater vasopressin increases and a higher rate of plasma volume loss during initial HUT (T1).
- Elevated ACTH and aldosterone responses persisted in symptomatic subjects post-training (T2), with greater norepinephrine increases.
- Post-training (T2), symptomatic subjects exhibited reduced vasopressin concentrations and a decreased rate of plasma volume loss during HUT.
Conclusions:
- Initial HUT findings in symptomatic individuals suggest heightened stimulation of volume-sensitive receptors due to rapid plasma volume decline.
- Exercise training enhanced tilt tolerance in symptomatic elderly individuals, correlating with diminished vasopressin levels and slower plasma volume loss during HUT.