AUTHOR=Hays Arnaud , Devys Simon , Bertin Denis , Marquet Laurie-anne , Brisswalter Jeanick TITLE=Understanding the Physiological Requirements of the Mountain Bike Cross-Country Olympic Race Format JOURNAL=Frontiers in Physiology VOLUME=9 YEAR=2018 URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2018.01062 DOI=10.3389/fphys.2018.01062 ISSN=1664-042X ABSTRACT=

Objectives: To evaluate the physiological requirements imposed by the current mountain biking Cross-Country Olympic (XCO) format.

Methods: Sixteen Cross-Country cyclists competing at national or international level participated in this study. All participants completed a simulated and a real official race on a cycling-accredited race track. Oxygen consumption (O₂) and heart rate (HR) values expressed as %O_2max and %HR_max, respectively, were divided into three physiological intensity zones. The first zone (Z1) was the physiological region below VT1, the second zone (Z2) corresponded to a region between VT1 and VT2, and the third zone (Z3) was located between VT2 and VO_2max. For power output, an additional fourth zone was considered above maximal aerobic power (MAP).

Results: When competing in the current XCO format, 37.0 ± 17.9% of the race is performed above the second ventilatory threshold at a mean intensity of 87% O_2max and 25% of the race was spent above MAP. This contribution varied between laps, with a very high intensity during the first lap and more aerobic subsequent laps. The durations of most of the periods beyond MAP oscillated between 5 and 30 s. Between these short, repeated bursts, low-intensity periods of exercise were recorded.

Conclusion: The current XCO race format is an acyclical and intermittent exercise comparable to high-intensity team sports. Moreover, our results highlight the relevance of O₂ values when analyzing XCO performance, they should be combined with commonly used HR and/or power output data.