Key points Our objective was to quantify endothelial function (via brachial artery flow‐
mediated dilatation) at sea level (344 m) and high altitude (3800 m) at rest and following
both maximal exercise and 30 min of moderate‐intensity cycling exercise with and without
administration of an α1‐adrenergic blockade. Brachial endothelial function did not differ
between sea level and high altitude at rest, nor following maximal exercise. At sea level,
endothelial function decreased following 30 min of moderate‐intensity exercise, and this …

We examined the hypotheses that 1) at rest, endothelial function would be impaired at high-
altitude compared to sea-level, 2) endothelial function would be reduced to a greater extent
at sea-level compared to high-altitude after maximal exercise, and 3) reductions in
endothelial function following moderate-intensity exercise at both sea-level and high-altitude
are mediated via an α1-adrenergic pathway. In a double-blinded, counter-balanced,
randomized and placebo-controlled design, nine healthy participants performed a maximal …