Muscle oxygenation patterns during a maximal incremental cycling and 20- km time trials

Abstract

Pacing strategies are necessary during endurance events in which the goal is to finish in as little time as possible. Both anaerobic and aerobic energy systems are utilized during cycling and running competitions. The Rating of Perceived Exertion (RPE) scale increases linearly as heart rate (HR), and power output (PO) increases. Muscle oxygen (O2) saturation within the working muscles typically mirrors this pattern. These components help determine the amount of energy an athlete can expend over the course of an event. Purpose: To determine how muscle O2 saturation changes with changes in PO during incremental and non-incremental exercise (20-km time trials). Methods: 9 subjects (8 male, 1 female) completed a maximal incremental exercise test, as well as a habituation 20-km trial, followed by a steady state (SS) 20-km time trial and two 20-km time trials with variations in nonuniform pacing. One variation had bursts separated by 2- km while the other was separated by 4-km. Athletes had 48-96 hours between trials. Muscle O2 saturation, PO, and HR were measured. RPE was recorded each kilometer. Repeated measures analysis of variance (RMANOVA) was used to determine the magnitude of differences between burst trials (2-km vs. 4-km rest). Results: There was no significant difference (p<.05) between the finishing times amongst the various 20-km protocols. Conclusion: This study revealed that the experimental intervals caused reciprocal changes in the magnitude of muscle oxygen and PO in the working muscle that are larger than the changes in a normally paced time trial.