Introduction: Mountain biking is a high-intensity endurance event. Studies have shown very high heart rates at the beginning of Olympic cross-country (XCO) competitions, corresponding to the fastest lap time (Impellizzeri and Marcora,2007; Stapelfeldt et al. 2004). However, the pacing strategy of XCO simulations has not been purposely examined. The aim was to examine the pacing strategy adopted during a simulated XCO race by bikers with different performance levels. Methods: Regional and national level bikers from Brazil (n=17, 30.2±5.6yr, 174.8±5.5cm, 67.9±6.3kg, 292.4±21.9Wmax and 64.4±4.5mL/kg/min) performed an incremental exercise test and an XCO race simulation on Computrainer™ (Seattle, USA). The simulation consisted of four laps (9.9km and 0-10% grade each). All athletes were asked to complete the race in the shortest time as possible. Heart rate (HR) was monitored using Polar®RS800CX. Subjects were divided into two groups (high and low) based on performance time. Results: No group x time interactions were found in lap time (p=0.153; linear), RPE (p=0.551; linear), HR (p=0.145; linear and cubic), power in W/kg (p=0.584; linear). The decrease in performance every lap was linear (p<0.001), with the last lap being slower than the first lap (3.49±0.61min;[CI95% 1.57,5.42];p=0.001). Based on a regression analysis, the riders decreased power every lap by 0.21W/kg corresponding to a lost of 1.6min. The power output decreased in the last lap compared to the first (42.9±7.2W; [CI95% 20.3,65.5]; p=0.000). Both HR and RPE increased linearly with the last lap showing higher values than the first (4,4±0.9beats/min; [CI95% 1.5, 7.2]; p=0.003 and 32.8±3.6; [21.3, 44.5]; p=0.000). The mean power and HR of the simulation was 234,9±31,1W (3,5±0,5W/kg) and 173,7±10,8beats/min. Discussion: During the simulation a pacing strategy similar to that reported for real events was found (Impellizzeri et al., 2002; Stapelfeldt et al., 2004). Furthermore, the pacing seems to be not influenced by the performance level. Although the strategy adopted (first laps faster) has been demonstrated to be detrimental to performance (Foster et al., 1993), the use of a faster start is technically important for the success in XCO because the cyclists can gain the first positions for avoiding to be slowed down by other riders, especially in the single tracks. In conclusion the study showed that the simulation has a good external validity and may be potentially useful for investigating the effect of interventions in controlled laboratory conditions.
© Copyright 2012 17th Annual Congress of the European College of Sport Science (ECSS), Bruges, 4. -7. July 2012. Veröffentlicht von Vrije Universiteit Brussel. Alle Rechte vorbehalten.