Cerebral blood flow response to intermittent head-down and head-up tilting in younger and older men

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Introduction & Aims: Aging and age-related conditions such as Alzheimer’s disease are associated with a decline in cerebral blood flow (CBF). Exercise training is known to delay this age-effect and improve cerebrovascular health. CBF regulation during exercise is complex and may differ with age. Improved understanding of the factors that modulate CBF would aid future exercise and therapy development. To determine the effect of oscillations in blood pressure, the aim of this study was to compare CBF responses during intermittent, repeated head-down (HDT) and head-up (HUT) tilt between younger and older men. Methods: 11 young (Y; 23.6±3 y) and 10 old (O; 68.8±2.6 y) healthy men performed 10 consecutive intermittent -6°HDT and +60°HUT using a tilt-table, alternating every 60s. Middle cerebral artery blood flow velocity (MCAv; transcranial Doppler ultrasound), mean arterial blood pressure (MAP; Finometer) and end-tidal CO2 (PetCO2) were measured continuously. Mean responses (40s) in each position were used for comparison. Effects of age (Y, O) and tilt-repetition (HDT, HUT over time) were determined using ANOVA. Results: Baseline MCAv data was lower (O: 37.1±10.4 vs Y: 61.0±6.7 cm/s, p<0.001) and MAP data was higher (O; 95.1±11 vs Y; 87.8±8.1 mmHg, p<0.05) in O. PetCO2 was not different (O; 33.4±3.1 vs Y; 36.1±3.0 mmHg, p=0.53). Over the 10 repeated tilts, the mean reduction in MCAv from HDT to HUT was greater in Y (O: -0.5±3.3 vs Y: -4.7±2.2 cm/s, p<0.01). MAP (O: -2.6±3.7 vs Y: -3.7±6.2 mmHg, p=0.64) and PetCO2 responses (O; -2.3±0.8 vs Y; -1.7±1 mmHg, p=0.15) were not different between age. There were no time effects for repeated tilting responses in either group. Conclusion: Repeated HDT and HUT led to an oscillatory MAP and CBF response in Y. Oscillatory MAP response was also seen in O, however, their CBF response remained unchanged. This absent CBF response in older men may be associated with impaired vascular function.
Original languageEnglish
Title of host publicationResearch to Practice 2016 : Conference Proceedings
Number of pages1
PublisherExercise & Sports Science Australia
Publication date04.04.2016
ISBN (Electronic)978-0-9925842-1-4
Publication statusPublished - 04.04.2016
EventResearch to Practice 2016 - Melbourne, Australia
Duration: 14.04.201616.04.2016

ID: 3106021

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