Effects of Lifelong Endurance Exercise on Cardiovascular Response to Orthostatic Stress in The Elderly Athletes

Abstract

BackgroundYoung endurance athletes have a greater decrease in stroke volume (SV) during orthostatic stress than age‐matched controls, due to a more compliant left ventricle (LV). Elderly athletes with lifelong training (EA) also have more compliant LV compared to elderly controls (C). However, it is unclear if the decrease in SV during orthostatic stress is greater in EA relative to C.MethodsFifty five subjects (EA 27, C 28) underwent right heart catheterization to measure pulmonary capillary wedge (PCWP) and right atrial (RAP) pressures, and SV at baseline and −15 and −30 mmHg lower body negative pressures (LBNP). To minimize the effect of external constraint on the LV, transmural pressure (TMP), which is the true preload for the LV, was calculated as PCWP‐RAP.ResultsAt baseline, SV index was larger in EA than C. PCWP appeared to be lower in EA, while TMP was similar between EA and C (3.4±1.4 vs. 3.5±1.4 mmHg, p=0.87). LBNP similarly lowered PCWP and TMP in EA and C (interaction p ≥ 0.56), while a greater decrease in SV index from baseline was observed in EA than C at −30 mmHg LBNP (17 vs. 12 ml/m2, p <0.01).ConclusionTMP was similarly regulated in EA and C at all loading conditions. EA had greater decrease in SV during orthostatic stress, probably due to a more compliant LV. Thus, similar to young athletes, EA may be more susceptible to orthostatic intolerance.