Predictive Validity of Critical Power, The Onset of Blood Lactate and Anaerobic Capacity for Cross-Country Mountain Bike Race Performance

Matthew C. Miller* and Paul W. Macdermid

Predictive Validity of Critical Power, The Onset of Blood Lactate and Anaerobic Capacity for Cross-Country Mountain Bike Race Performance.

Critical power is emerging as an important indicator of high intensity endurance exercise capability. Little is known regarding its ability to predict performance during high intensity intermittent events such as Olympic format cross country mountain bike racing. Therefore, the purpose of this pilot study was to assess the validity of critical power and anaerobic capacity
compared to the more traditional measure of power at physiological thresholds previously related to race performance.

Five nationally competitive athletes volunteered for this study. Participants completed a cycle ergometry step test to exhaustion in order to determine the anaerobic threshold. On a separate occasion participants completed a 3-minute all-out test against a fixed resistance to determine critical power and anaerobic capacity.

Olympic format cross country mountain bike racing (XCO-MTB) is a high intensity intermittent sport lasting between 60-90 min, taking in a variety of terrains or obstacles and requiring both high rates of aerobic and anaerobic energy production. Un-typical of other endurance sports starting on mass, XCO-MTB requires maximal effort from the start to gain or hold positional advantage so as not to impair overall performance. As such initial field based research identifies that 82% of total race time corresponds to power outputs greater than the Lactate Threshold (LT) equating to 90% HRmax and 84% VO2max.

While interesting such a holistic view of power data neglects key components of the sport such as the intermittent nature of propulsive and non-propulsive work done in combination with different components of strength or power.

Sport Exerc Med Open J. 2015; 1(4): 105-110. doi: 10.17140/SEMOJ-1-116