THE SCIENCE OF XCO-MOUNTAIN BIKING

Tying in with our XCO-theme, coaching masterminds’ DR MIKE POSTHUMUS AND BEN CAPOSTAGNO explain what it takes to succeed at this discipline.

Jaroslav Kulhavy
Photo Credit: Michal Cerveny

An XCO race is a mass start event that typically lasts between 90 and 105 minutes and takes place over numerous laps of a predetermined course. The course usually consists of climbs, technical descents and singletrack. The intermittent nature of XCO requires specific physiological characteristics, which may differ from those required for success in other cycling disciplines. In this article, we will discuss what it takes to be a successful XCO racer. ON YOUR MARKS … A lap of an XCO circuit will have a large amount of singletrack, which may make passing slower riders tricky. Riders’ starting positions are determined based on the ranking relevant to the specific race. Starting towards the back of the field will result in an immediate disadvantage, compared to riders who start towards the front and can continue to ride at their desired pace. Researchers at Massey University in New Zealand performed a longitudinal analysis of the effect start positions had on finishing positions in UCI World Cups from 1997 – 2007. Their results showed that finishing positions are highly dependent on start positions. In addition, the researchers recommended that developing athletes should explore strategies that could assist them in improving their starting position. THE PHYSIOLOGY OF XCO Physiological variables determined during standard laboratory testing fail to predict XCO performance on their own. The main reason for this is the absence of an “XCO-specific” test that can provide better insight into the rider’s ability to cope with the demands of the event. 1 Oxidative (aerobic) capacity Endurance or oxidative capacity is often determined by measuring two variables: + VO2Max – The athlete’s maximal rate of oxygen uptake and use + Peak power output (PPO) – Which is the final workload (power output) reached during a standard incremental test in a laboratory Both VO2max and PPO have been associated with XCO performance. However, despite the somewhat strong association between oxidative capacity and XCO performance, the intermittent nature of XCO racing places a high premium on glycolytic (anaerobic) capacity. 2 Glycolytic (anaerobic) capacity Initial research into factors associated with XCO performance were fairly unidimensional and only examined the association between data from standard VO2max testing (VO2max, PPO and threshold) and XCO performance. Researchers quickly discovered that despite the strong correlations between these variables and XCO performance, a big part of the proverbial puzzle was missing. The intermittent nature of XCO racing means that performance will most likely be heavily reliant on an athlete’s ability to repeatedly produce a highpower output. A recent study examined the association between intermittent power output, measured by a series of sprints with short rest or recovery periods and XCO performance. The study made use of an intermittent power test, which consisted of 20 intervals of 45 seconds of work and 15 second rest periods. The cyclists in this study also performed a 20-minute time-trial in order to determine their Functional Threshold Power (FTP) (95% of the average power output for the 20 minute effort). The cyclists then all took part in an XCO race and the relationship between relative FTP, Intermittent Power (IP) and race performance was examined. Interestingly, the best predictor of XCO race performance was in fact the intermittent power test. While the association between FTP and race performance was strong, it was not as good a predictor of performance as IP was. The increased popularity and availability of power meters means that intermittent power output can be determined from a field test or training session. For example, two sets of 6 x 40 second sprints with 20 seconds of recovery (A session commonly referred to as 40:20’s), can provide a useful performance predictor for XCO athletes. SKILLS WILL PAY THE BILLS XCO tracks are becoming increasingly technical and this places a high premium on the skill level of XCO racers. Riders who are able to successfully negotiate technical singletrack descents without additional pedalling, should recover faster than their less skilled competitors. In addition, recognising the most appropriate line is also an important skill to master. In summary, XCO performance will be determined by a host of factors including an athlete’s aerobic capacity, their ability to repeatedly produce high power outputs and their skill level.

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