Effects of prior high-intensity endurance exercise in subsequent 4-km cycling time trial performance and fatigue development

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 ((V) over dotO(2)) 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 (V) over dotO(2) 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. (C) 2021 Elsevier Masson SAS. All rights reserved.

Automated summary

The study investigates the effects of prior high-intensity endurance exercise on time trial performance and fatigue responses. The results show that prior high-intensity endurance exercise has positive effects on subsequent time trial performance, despite the development of exacerbated peripheral fatigue. This response may be driven by greater aerobic reliance and exertion tolerance.