Resumo
The age-dated eff&cts on the time coune of the rapid incicase in blood flow at the omet of excrcise m largely unknown. In addition, whether this timt course is altercd with training in olderpeople is Plso UOClear. It appeas that tûis dearth of iaformation was penly due to the iack of non-invasive mezhodr of masmmmts thar could pment high temporal icsolution and could be used during the exacise. hotber diffidty that mi@ also have contniuted to this lack of ioformation was thai the mec- involved in blood flow kinetics mguiation in humans are not weli undtrstobd, It is aiso aot clear how these mechaaisms an affécted by age or physical training. In order to addrcss the questions about whether blood flow kinetics were altered by aging or physicai activity, three studies were developed. In ail thne studies, foi.eami mean blood velocity and mean arterial pafusion pressure were muwrrd on a kat-by-beat basis, using pulsed Doppler ultrasound and a plethysmographic hger niff, respectively. This aüowed calculation of forearm vascular conductance also on a bat-by-kat basis. The diameter of the brachial artery was measd at several points in thne aud during exercis. Since the exercise mean diameter was aot different hm the resting values, it was assumed that mean blood velocity kinetics represented the blood flow kinetics.
