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

Abstract

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 (mean±s: age:31.4±9.3 years; mass: 70.8±9.5 kg; VO 2max : 63.8±7.0 ml•kg-1 •min) 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. Laboratory data showed no differences (P=0.057) between the power output at the onset of blood lactate or critical power and neither related to anaerobic capacity (p=0.499 and p=0.344, respectively). Performance was measured via race data analysis gathered from a USA Cycling sanctioned race. Linear regression was used to assess the prediction of performance. Critical power predicts Olympic format cross country mountain bike performance (r 2 =0.943, p=0.006) to a greater degree of accuracy than anaerobic threshold (r 2 =0.785, p=0.046) or anaerobic capacity (r 2 =0.477, p=0.197) with less error (39.413; 76.526; 118.9 s, respectively). Therefore, the ability to sustain a high intensity effort for the race duration, determined via critical power rather than the onset of blood lactate, is likely more valuable to cross country mountain bike athletes than anaerobic capacity.