Intensity Profile during an Ultra-endurance Triathlon in Relation to Testing and Performance

We examined the heart rate (HR)-based intensity profile during an ultra-endurance triathlon (UET) estimated from the individual HR-oxygen uptake (VO2) relationship during specific graded tests, relating it to race performance. 9 male ultra-endurance triathletes completed the study. Before racing, subjects performed graded exercise tests involving cycle (C) ergometry, treadmill running (R) and free swimming (S) for peak VO2 and HR at ventilatory thresholds (VT). Exercise-specific HR-VO2 regression equations were developed. Mean race HR was higher during S (149.2 (10.1) bpm) than during C (137.1 (5.7) bpm) and R (136.2 (10.5) bpm). During C and R, HR was below both VT (11% and 27-28%). HR differences between S and C correlated with C, R and final times. The greatest differences between S and C were related to the worst times in the next stages. These ultra-endurance triathletes performed S at a higher relative intensity, which was inversely correlated with performance in the following stages. The best predictors of final racing time (81%) were weight-adjusted VO2max and HR difference between C and S. A more adequate characterization of the time pattern during the whole race, especially during S, adds new information concerning the intensity profile and cardiovascular demands of an UET race.