Cardiorespiratory and cerebrovascular responses to head-up tilt I: Influence of age and training status

► Orthostatic tolerance is unaffected by age and by fitness. ► Older individuals exhibited attenuated HR and SV responses to HUT. ► Fitter individuals exhibited less reduction in Q̇ and more maintained TPR with HUT. ► Despite ageing- and fitness-induced physiological adaptations, the cardiorespiratory and cerebrovascular systems adapt well to orthostatic challenge in healthy individuals.