Physiological Response to Cyclocross Racing

Abstract

Introduction: Cyclocross is a growing discipline of cycling that combines elements of both mountain biking and road racing. The purpose of the study was to describe the intensity of the sport of cyclocross using competition heart rate (HR) and blood lactate [La-] data.
Methods: Eight experienced cyclocross racers participated in both a laboratory graded exercise test and a cyclocross race. During laboratory testing, peak oxygen consumption (V ̇ O2peak) was determined and HR at the following intensities was established: LOW (HR below 2 mmol.L-1), MODERATE (MOD, HR between 2 and 4 mmol.L-1), and HIGH (HR above 4 mmol.L-1). During field testing, subjects participated in a cyclocross race. HR was monitored throughout the race and [La-] was measured immediately post. Time in each exercise zone (LOW, MOD, HIGH) was then calculated using data from laboratory testing.
Results: Subjects had an average HR of 170.8±10.1 beats per minute (bpm) and a HRmax of 177.8±8.4 bpm during the race. The percentage of time in LOW, MOD, and HIGH was 0.4±0.4%, 6.1±6.7%, and 93.6±6.7%, respectively. No significant mean difference was seen in time (p=0.17) or HR (p=0.29) per lap. Post-race blood lactate was 8.3±1.1 mmol.L-1.
Conclusion: The study shows that cyclocross is a high intensity sport characterized by sustained elevated HR responses and high post [La-] values.