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

Abstract

CitationMiller MC, Macdermid PW. Predictive validity of critical power, the onset of blood lactate and anaerobic capacity for cross-country mountain bike race performance. Case ReportPage 105 ABSTRACTCritical 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.

Exercise Intensity and Pacing Pattern During a Cross-Country Olympic Mountain Bike Race

“…Several studies have shown the importance of aerobic characteristics for performance, such as maximal oxygen uptake (V̇O 2max ; Impellizzeri and Marcora, 2007 ; Hays et al, 2018 ), maximal aerobic power (MAP) output ( Granier et al, 2018 ; Hays et al, 2018 ), and ventilatory and lactate thresholds ( Impellizzeri et al, 2005a ; Miller et al, 2014 ; Miller and Macdermid, 2015 ; Viana et al, 2018 ). Anaerobic power has also been classified as an important determinant of performance because of the intermittent aspect of XCO racing ( Inoue et al, 2012 ), but to date, there have been limited studies conducted.…”

“…In addition, laboratory tests of aerobic fitness are not readily available to coaches and athletes due to the need for advanced equipment. Noticing the lack of an ecological testing method, Miller and Macdermid (2015) proposed critical power (CP) as an ecological framework to assess performance in XCO. CP is considered to be the highest sustainable rate of oxidative metabolism without a continuous loss of homeostasis, defined as the boundary between steady state and non-steady state exercise ( Poole et al, 1988 ; Jones et al, 2008 ).…”