Journals of Gerontology Series A: Biological Sciences and Medical Sciences, Vol 50, Issue 6 M324-M329, Copyright © 1995 by The Gerontological Society of America

JOURNAL ARTICLE

Hormonal responses in elders experiencing pre-syncopal symptoms during head-up tilt before and after exercise training

JF Carroll, CE Wood, ML Pollock, JE Graves, VA Convertino and DT Lowenthal
Center for Exercise Science, College of Medicine, University of Florida, Gainesville, USA.

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 (T1) and after (T2) 6 months of endurance training. METHODS. Based on responses to HUT at T1, 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 T1 HUT but completed 15 minutes of HUT at T2. Training consisted of treadmill walking or stairclimbing 3 x/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; tilt-induced changes in PV were calculated from changes in hemoglobin and hematocrit. RESULTS. During T1 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 T1 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. T1 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.

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