Objectives To investigate the effects of prior high-intensity endurance exercise on time trial (TT) performance and fatigue responses. Equipment and methods Eleven male cyclists visited the lab in two separate visits. The first visit was composed by a maximal cycling incremental test (MIT) followed by 15 min of passive rest before a 4-km cycling TT. The second visit (control, CON) was composed by moderate-intensity exercise for 5 min before the TT. Fatigue of knee extensors was assessed by isometric maximal voluntary contractions (IMVC), while the central (voluntary activation [VA]) and peripheral fatigue (peak torque of potentiated twitches [TwPt]) were evaluated using electrically-evoked contractions performed before and 1 min after the TT. Power output (PO), oxygen uptake (VO2) and rating of perceived exertion (RPE) were recorded throughout the TT. Results TT performance (+2.6%) and average PO (+5.7%) improved in MIT compared to CON condition. While peripheral fatigue level was greater in MIT condition (P < 0.05), the central fatigue was lower compared to CON condition (P < 0.05). There were greater overall VO2 values (3.9 ± 0.4 vs 3.6 ± 0.4 L·min-1) but similar RPE responses (15 ± 2 vs 15 ± 3 a.u.) in MIT compared to CON. These findings indicate that prior high-intensity endurance exercise has positive effects in subsequent TT performance compare to moderate-intensity warm-up, despite exacerbated peripheral fatigue development. This response might be driven by greater aerobic reliance and exertion tolerance.
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