Abstract
Although postexercise syncope in endurance athletes is well recognized, the underlying mechanism is unknown. To determine whether endurance athletes exhibit the substantial hypotension during postexercise orthostatic stimulation, we conducted 5‐min head‐up tilt (HUT) tests before and after the 1‐hour moderate intensity cycling in young sedentary (S: n=8), endurance‐trained (E: n=8), and resistance‐trained (R: n=8) men. After the exercise the HUT‐induced vasoconstriction was significantly blunted in S and E groups. Significantly larger increase in the HUT‐induced fall of stroke volume was seen in E and R groups. Contrast to our hypothesis, endurance trained men did not exhibit a substantial drop of mean arterial pressure and/or pre‐syncope symptom during postexercise HUT despite the accumulated factors which facilitates orthostatic hypotension. This phenomenon might be explained by the greater augmentation of HUT‐induced tachycardia: the postexercise increase in tachycardia response was significantly greater in the endurance‐trained (+118% from preexercise) than those in the other groups (+45–50%). Collectively, during postexercise orthostatic challenge (at least in an early phase), endurance athletes maintain arterial pressure mainly by the enhanced tachycardia response.Grant: Nakatomi Foundation, Japan.
Published Version
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