Author(s): FUK, A., VILLANOVA, S., QUAGLIAROTTI, C., FILIPAS, L., GALLO, G., GRAMAZIO, A., DELLO STRITTO, E., BAZZUCCHI, I., CONTI, A., LAMBERTS, R.P., PIACENTINI, M.F., Institution: UNIVERSITY OF ROME, FORO ITALICO, Country: ITALY, Abstract-ID: 2320

INTRODUCTION:
Long-distance triathlons are ultra-endurance multisport events that require sustaining high training volumes in the “moderate-to-heavy” intensity domain (MTHID)1. Recently, the concept of durability, defined as the time of onset and magnitude of physiological decline over time during prolonged exercise, has been studied in isolated cycling and running activities2. However, changes in running profiling when transitioning from prolonged cycling have yet to be studied. The aim of this study was to evaluate physiological changes while running at the MTHID after prolonged cycling and changes in performance during a 5-min time trial (TT) to better understand specific training and racing demands.
METHODS:
Seven trained male triathletes (age: 36±8 y, relative VO2max: 61.7±4.9 ml·kg-1·min-1) completed two running tests on separate days, one performed in a “fresh” (FRE) and one in “fatigued” (FAT) condition. Fatigue was induced by performing a prolonged 150-min indoor cycling at 90% of LT1 power. The testing protocol was a submaximal incremental test on a treadmill with 5-min steps until the second lactate threshold (LT2), followed by an outdoor all-out 5-min TT. VO2, respiratory exchange ratio (RER), ventilation (VE), respiratory frequency (RF), HR, BLa and RPE were determined during the steps below (UNDER) and just above (OVER) the LT1FRE and compared to the same speed in the FAT condition. In addition, distance completed during the 5-min TT were compared between the conditions. Due to the small sample size, data were analyzed with a Wilcoxon signed rank test (p < 0.05) and presented as median (interquartile range).
RESULTS:
Differences in both the UNDER and OVER period between the FRE and FAT condition were found in VO2 [UNDER: VO2FRE: 45.3(42.0-46.8) vs VO2FAT: 47.5(46.1-53.2) p=0.02; OVER: VO2FRE 47.7(46.3-51.2) vs VO2FAT 52.0(47.8-55.1) ml·kg-1·min-1; p=0.02], HR [UNDER: HRFRE 153(142-154) vs HRFAT 157(147-161); p= 0.02; OVER: HRFRE:160(150-163) vs HRFAT:163(153-168) bpm; p=0.02], BLa [UNDER: BLaFRE 1.6(1.5-1.7) vs BLaFAT 2.2(2.2-2.6); p=0.02; OVER: BLaFRE 2.1(1.9.-2.2) vs BLaFAT 2.4(2.2-2.8) mmol·L-1; p=0.02] and RER [UNDER: RERFRE 0.92(0.88-0.95) vs RERFAT 0.84 (0.83-0.87); p=0.04; OVER: RERFRE 0.92(0.90-0.96) vs RERFAT 0.87(0.84-0.89); p=0.02] Total distance covered during the 5-min TT, was less in the FAT condition [FRE:1483(1405-1538) vs FAT:1406(1374-1500) m; p=0.02].
CONCLUSION:
Induced fatigued, resulted in higher VO2 costs, HR and BLa levels, with lower RER levels in data UNDER and OVER LT1 during a standardized submaximal test. In addition, the mean distance covered during a 5-min TT was lower in the FAT condition. These findings indicate that physiological markers change with increasing levels of accumulating fatigue, which should be considered when prescribing training and determining racing strategies in triathlons.