Decrements in Cycling Performance are Dependent on the Intensity and Duration of Prior Exercise

Abstract

The maximal lactate steady state (MLSS) is a physiological model that can be used to delineate the heavy- from the severe-intensity domain of exercise. The importance of this threshold has been repeatedly demonstrated, as it differentiates intensities that result in stable physiological responses from those that progress towards maximal values. To understand the implications that exercise performed at this intensity has on subsequent performance, a recent study demonstrated that time-to-exhaustion (TTE) performance is reduced following prior exercise performed at the power output (PO) corresponding to MLSS (MLSSp) and reduced even further following a small (i.e., 10 watt (W)) increase above MLSSp. Therefore, the purpose of this thesis was to determine whether submaximal intensities (i.e., sub-MLSSp) as well as different durations at MLSSp would have any impact on subsequent TTE performance, within the severe-intensity domain. The results from this thesis demonstrated curvilinear and linear reductions in TTE performance following increase in the intensity and duration of the preceding bout of exercise, respectively. These results highlight that the capacity within the severe-intensity domain is dependent on both the intensity and duration of a prior bout of exercise. Moreover, these findings also illustrate the importance of properly determining thresholds and the exercise intensity domains on an individual basis, as small changes in the PO surrounding MLSS have detrimental effects on performance. Lastly, this thesis also highlighted the importance of perceptual responses during exercise. Rating of perceived exertion (RPE) was associated with the reduction in TTE performance for both the intensity and duration conditions, indicating that the capacity within the severe-intensity domain can be estimated by RPE assessed immediately prior to each TTE trial.