European journal of applied physiology
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Eur. J. Appl. Physiol. · Mar 2011
Clinical TrialSyncope is unrelated to supine and postural hypotension following prolonged exercise.
Syncope is widely reported following prolonged exercise. It is often assumed that the magnitude of exercise-induced hypotension (post-exercise hypotension; PEH), and the hypotensive response to postural change (initial orthostatic hypotension; IOH) are predictors of syncope post-exercise. The aim of this study was to determine the relationship between PEH, IOH, the residual IOH and syncope following prolonged exercise. ⋯ Although the magnitude of IOH was similar to post-exercise [-28 ± 12 vs. -20 ± 14% (pre-exercise); P > 0.05], the BP recovery following IOH was incomplete [-9 ± 9 vs. -1 ± 11 (pre-exercise); P < 0.05]; however, neither showed a relation to HUT-time completed (r(2) = 0.18, r (2) = 0.01; P > 0.05, respectively). Although an inability to maintain BP is a common feature of syncope post-exercise, the magnitude of PEH, IOH and residual IOH do not predict time to syncope. Practically, endurance athletes who present with greater hypotension are not necessarily at a greater risk of syncope than those who present with lesser reductions in BP.