Performance monitoring during a mountain biking race.

Previous studies analyzing the performance in road and MTB cyclists report usually oxygen uptake and lactate data collected during incremental tests. Infrequent are the observations of physiological parameters during the race. The aim of this study is to assess the performance of Cyclists of Italian National Team during an official MTB competition through the continuous monitoring of heart rate (HR), speed, and revolutions per minute (RPM). Our ultimate goal is to obtain a more careful performance model including also an indirect estimate of the physiological load, related to the maximum oxygen uptake (VO2max) and the anaerobic threshold (AT). This will be carried out analyzing the relationship between HR collected during the race and physiological parameters obtained with incremental tests. In the laboratory, the cyclists warmed up for 20' at 100W using a cycloergometer Monark, adapted to allow the use of his own bike to each of the athletes. VO2max was assessed through an automatic analyzer (Vmax29, Sensor Medics, Iorba Linda, California), HR was collected, also during the race, with an heart rate monitor (Vantage NV, Polar Electro Oy, Finland), allowing to register speed and RPM too. In the incremental test, power was increased in 25 W every 30s until exhaustion. VO2Max is the mean VO2 of the last step. HR, VO2 and power were calculated as maximal values and relative to the AT, estimated at a blood lactate concentration of 4 mMol/l. We tested 14 athletes belonging to the Italian National Team, participating to an official international MTB competition. From the initial group we selected 6 subjects having different results in the initial test, and different strategic behaviours - then different results - during the race. The race course and the tactical behaviour render the performance model very different between the athletes and also for the same athlete during the 7 rounds of the course. From the trend of parameters we observed 4 racing strategies: 1. High load (intensity near the maximal) for a third of the duration of the competition, especially in the central phases determinant for the selection, then control of the race at a lower intensity 2. Regular race with a load a few inferior to AT without reaching the maximum metabolic load (controlled race, nearly a training) 3. High load at the beginning, then administration of the race with a strain necessary to maintain the acquired0 position 4. More frequent load around the AT, with under- and over-AT phases, with a Gaussian distribution of the load.