The Physiology of Contemporary Olympic Cross-Country Mountain Biking: A Systematic Review

Olympic Cross-Country (XCO) mountain biking has evolved since its 1996 Olympic debut, with races becoming up to 40% shorter and more technically demanding. These changes may have altered the physiological demands, challenging the applicability of earlier evidence. This systematic review examines the physiology of contemporary XCO, focusing on athletes' characteristics, race demands, and training interventions.

A systematic search was conducted in PubMed, Web of Science, Scopus, and Embase. Fifty-three studies involving national to elite-level XCO athletes competing under the current race format were included. Risk of bias was assessed using the JBI Critical Appraisal Tool.

Findings highlight that XCO athletes maintain exceptional aerobic capacity as in the former version of the discipline, but evidence points to a greater importance of high-intensity, short-duration efforts. A more intermittent effort pattern has been reported during races, with athletes spending a quarter of the time above their maximal aerobic power, interspersed with periods of technical riding that impose a high physiological demand as evidenced by a sustained high oxygen uptake. A fast-start pacing strategy is frequently reported, with velocity stabilizing or slightly decreasing in later laps, although the interpretation may be partly influenced by the structure of the start lap. Effective training regimens include high-intensity interval training, sprint interval training, and strength training, although direct performance assessments are scarce.

Overall, the current evidence confirms that the evolution of XCO has reshaped the discipline's physiological profile, shifting towards greater anaerobic contribution while maintaining high aerobic demands. Future research should address the underrepresentation of female athletes and methodological limitations, particularly in participant characterization and control of confounding factors.