title: Reliability of orthostatic responses in healthy men aged between 65 and 75 years.
abstract: The purpose of this study was to investigate the short-, medium- and long-term reproducibility of cardiovascular responses during 90 degrees head-up tilt (HUT) in healthy older men. Twenty-eight healthy male subjects aged 69 (95% confidence intervals, 68-70) years participated in the study. Eight subjects underwent duplicate 90 degrees HUT tests on consecutive days, while 20 subjects underwent four 90 degrees HUT tests performed at baseline, and after 1 week, 1 month and 1 year. Following a 20-min supine resting period, each subject was rapidly tilted to the upright vertical position (90 degrees HUT) and remained in that position for 15 min. Beat-by-beat recordings of mean (MAP), systolic (SBP) and diastolic (DBP) pressures were made via Finapres, while heart rate (HR) was monitored continuously from an electrocardiogram. No significant test-retest differences (P > 0.05) were observed for the changes in HR, MAP, SBP or DBP during 90 degrees HUT. These measurements demonstrated high reproducibility (intraclass correlation coefficient, r = 0.91-0.99, P < 0.05). The supine resting and tilted HR, MAP, SBP and DBP over the 1-week, 1-month and 1-year period were not significantly different (P > 0.05) from baseline, and demonstrated high reproducibility (intraclass correlation coefficient, r = 0.82-0.98, P < 0.05). The results of this study demonstrate that in healthy older men, cardiovascular responses during orthostasis are highly reproducible, and this reproducibility is maintained over a 12-month period. These findings demonstrate that the 90 degrees HUT test offers a reproducible method of monitoring longitudinal orthostatic responses in healthy older men.
authors.affiliation: Athlete and Coach Support Services, Queensland Academy of Sport, PO Box 956, Sunnybank, Queensland 4109, Australia. tim.gabbett@qld.gov.au
authors.forename: Tim J
authors.initials: TJ
authors.lastname: Gabbett
authors.forename: Greg C
authors.initials: GC
authors.lastname: Gass
mesh_terms: D000328:Adult; D000368:Aged / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology; D004562:Electrocardiography; D006339:Heart Rate / Q000502:physiology; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D007024:Hypotension, Orthostatic / Q000503:physiopathology*; D008297:Male; D011187:Posture / Q000502:physiology*; D012016:Reference Values; D015203:Reproducibility of Results; D012146:Rest / Q000502:physiology; D016683:Supine Position / Q000502:physiology; D013997:Time Factors