Hormonal Responses in Elders Experiencing Pre-syncopal Symptoms During Head-up Tilt Before and After Exercise Training

Document Type

Article

Publication Date

11-1995

Publication Title

The Journals of Gerontology, Series A

Keywords

norepinephrine, epinephrine, syncope, aerobic exercise, vasopressins, aldosterone, corticotropin, maximum heart rate, exercise, hemoglobin, nausea, blood plasma volume, supine position, sweating, hematocrit, lightheadedness, older adult, treadmills, symptom onset, transverse spin relaxation time

Abstract

Background. Hormonal responses of elderly individuals experiencing pre-syncopal symptoms during head-up tilt testing (HUT) were compared with responses of nonsymptomatic subjects both before (Tl) and after (T2) 6 months of endurance training.

Methods. Based on responses to HUT at Tl, 35 men and women (ages 61–79 years) were placed into symptomatic and nonsymptomatic groups for analysis. Symptomatic subjects (n = 5) experienced lightheadedness, nausea, sweating, or syncope during Tl HUT but completed 15 minutes of HUT at T2. Training consisted of treadmill walking or stairclimbing 3 × /wk, 30–45 min/day, at 75–85% of maximal heart rate reserve. Adrenocorticotropic hormone (ACTH), vasopressin, aldosterone, norepinephrine, epinephrine, hemoglobin, and hematocrit were measured during supine rest prior to HUT, and either at the end of the 15-minute HUT or at symptom onset. Plasma volume (PV) was measured at supine rest; tiltinduced changes in PV were calculated from changes in hemoglobin and hematocrit.

Results. During Tl HUT, symptomatic subjects had greater increases in vasopressin and a greater rate of PV loss (p < .05). Increases in ACTH and aldosterone were greater in symptomatic subjects at Tl and T2, while increases in norepinephrine were greater at T2 (p < .05). Reductions in tilt-induced vasopressin concentration and a decreased rate of PV loss were seen at T2 in symptomatic subjects.

Conclusions. Tl results from symptomatic subjects are consistent with greater stimulation of volume-sensitive receptors induced by a greater rate of fall in PV. Exercise training resulted in increased tilt tolerance for symptomatic subjects associated with reductions in vasopressin concentration and rate of PV loss during tilt.

Comments

© 1995 by The Gerontological Society of America

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