Background and aims: Endurance training may reduce orthostatic tolerance. Elderly people are prone to orthostatic intolerance, but the impact of endurance training in old age has been insufficiently explored.
Methods: 54 healthy men; 30 endurance athletes and 24 controls, free from medication and chronic diseases, were subjected to head-up tilt tests: 30º for 10 min and 70º for 40 min. Non-invasive recordings of blood pressures, heart rate, stroke volume, end diastolic volume, total peripheral resistance, heart rate variability, blood pressure variability, and baroreflex sensitivity were obtained. We registered terminations of test due to frank syncope or unbearable presyncopal symptoms.
Results: Mean age 71 years (range 65-84); athletes had lower body mass index (23.4 versus 24.8, p < 0.05) and lower resting heart rate (50 versus 61, p < 0.01). Blood pressures and total peripheral resistance were equal. End diastolic volume index, baroreflex sensitivity, and heart rate variability were higher among athletes, both HF-RRI (high-frequency variability, reflecting parasympathetic activity) and LF-RRI (low-frequency variability, reflecting both sympathetic and parasympathetic activity). Syncope or presyncopal symptoms occurred in 11 persons, 4 athletes and 7 controls (p = 0.2). Cox Regression analysis showed that higher heart rate at rest was the only variable associated with syncope.
Discussion: Orthostatic tolerance was not reduced among elderly endurance athletes. Rather, there was a trend towards better orthostatic tolerance, which might be attributed to stronger parasympathetic cardiovascular control and larger blood volume.
Conclusions: Better orthostatic tolerance might be an additional benefit of physical activity in older age.