Pacing in cycling: a study about the neuromuscular fatigue and metabolic interface

Abstract

More recent studies have suggested that power output distribution along a race adopted in endurance sports, defined as pacing, is able to influence the athletic performance. It is believed that pacing reflects the metabolic alterations produced in exercised muscles, which has a feedback sent to central nervous system by afferent nervous, resulting in an alteration in neural drive. It has been proposed that the alteration in neural drive occurs in order to maintain an overall physiological steady state and avoid the development of the neuromuscular fatigue. Although previous studies have provided relevant insights about main factors related to pacing, it is important to note that these suggestions remained speculative. These studies have not determined the relationship between pacing and the contributions of central and peripheral mechanisms for the development of the neuromuscular fatigue. In addition, it is also important to highlight that the overall physiological steady state in endurance exercise has been determined only in workload constant tests and using a small number of metabolites (~10 metabolites). Therefore, the main objective of this proposal will be to analyze the contributions of central and peripheral mechanisms for the development of the neuromuscular fatigue, as well as their relationship with metabolic profile determined in the different phases of pacing during a 4-km cycling time-trial (4-km TT). Based on previous studies suggesting that the neuromuscular fatigue during short-duration exercise (3-5 min) is mainly determined by peripheral processes and that the metabolic profile is maintained stable during endurance exercise, it is hypothesized that: i) there will be a higher contribution of peripheral fatigue at the first phases of the 4-km TT, while at the last phase there will be a higher contribution of central fatigue, ii) there will be an overall physiological steady state during 4-km TT with metabolic profile being composed mainly by metabolites related to aerobic metabolism. (AU)