title: Estimated aortic stiffness is independently associated with cardiac baroreflex sensitivity in humans: role of ageing and habitual endurance exercise.
abstract: We hypothesised that differences in cardiac baroreflex sensitivity (BRS) would be independently associated with aortic stiffness and augmentation index (AI), clinical biomarkers of cardiovascular disease risk, among young sedentary and middle-aged/older sedentary and endurance-trained adults. A total of 36 healthy middle-aged/older (age 55-76 years, n=22 sedentary and n=14 endurance-trained) and 5 young sedentary (age 18-31 years) adults were included in a cross-sectional study. A subset of the middle-aged/older sedentary adults (n=12) completed an 8-week-aerobic exercise intervention. Invasive brachial artery blood pressure waveforms were used to compute spontaneous cardiac BRS (via sequence technique), estimated aortic pulse wave velocity (PWV) and AI (AI, via brachial-aortic transfer function and wave separation analysis). In the cross-sectional study, cardiac BRS was 71% lower in older compared with young sedentary adults (P<0.05), but only 40% lower in older adults who performed habitual endurance exercise (P=0.03). In a regression model that included age, sex, resting heart rate, mean arterial pressure (MAP), body mass index and maximal exercise oxygen uptake, estimated aortic PWV (β±s.e.=-5.76±2.01, P=0.01) was the strongest predictor of BRS (model R(2)=0.59, P<0.001). The 8-week-exercise intervention improved BRS by 38% (P=0.04) and this change in BRS was associated with improved aortic PWV (r=-0.65, P=0.044, adjusted for changes in MAP). Age- and endurance-exercise-related differences in cardiac BRS are independently associated with corresponding alterations in aortic PWV among healthy adults, consistent with a mechanistic link between variations in the sensitivity of the baroreflex and aortic stiffness with age and exercise.
authors.affiliation: Department of Health and Human Physiology, University of Iowa, Iowa City, IA, USA.|Abboud Cardiovascular Research Center, University of Iowa, Iowa City, IA, USA.|UI Center for Hypertension Research, University of Iowa, Iowa City, IA, USA.|Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA, USA.
authors.forename: G L
authors.initials: GL
authors.lastname: Pierce
authors.affiliation: Department of Health and Human Physiology, University of Iowa, Iowa City, IA, USA.
authors.forename: S A
authors.initials: SA
authors.lastname: Harris
authors.affiliation: Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO, USA.
authors.forename: D R
authors.initials: DR
authors.lastname: Seals
authors.affiliation: Abboud Cardiovascular Research Center, University of Iowa, Iowa City, IA, USA.|Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA, USA.|Department of Physical Therapy and Rehabilitation Science, University of Iowa, Iowa City, IA, USA.
authors.forename: D P
authors.initials: DP
authors.lastname: Casey
authors.affiliation: Department of Internal Medicine, University of Iowa, Iowa City, IA, USA.
authors.forename: P B
authors.initials: PB
authors.lastname: Barlow
authors.affiliation: Department of Health and Human Physiology, University of Iowa, Iowa City, IA, USA.|Abboud Cardiovascular Research Center, University of Iowa, Iowa City, IA, USA.|UI Center for Hypertension Research, University of Iowa, Iowa City, IA, USA.
authors.forename: H M
authors.initials: HM
authors.lastname: Stauss
mesh_terms: D000222:Adaptation, Physiological; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000375:Aging; D017704:Baroreflex; D001794:Blood Pressure; D002319:Cardiovascular System / Q000294:innervation*; D003430:Cross-Sectional Studies; D005260:Female; D006184:Habits; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D010807:Physical Endurance; D063177:Pulse Wave Analysis; D057185:Sedentary Behavior; D013997:Time Factors; D059289:Vascular Stiffness; D055815:Young Adult