Prolonged stage duration during incremental cycle exercise: effects on the lactate threshold and onset of blood lactate accumulation

Abstract.

The aim of this study was to investigate whether increasing the duration of workloads from 3 min to 8 min during incremental exercise would influence workload (W), oxygen consumption ($\dot V{\rm O}_{\rm 2}$ ) and heart rate (HR) at the lactate threshold (LT) and the onset of blood lactate accumulation(OBLA). Two groups of six male cyclists were assigned to a well-trained (WT) and recreational (REC) group on the basis of their performance in a maximal incremental ramp test. Each subject then performed two incremental lactate tests (EXT) consisting of six workloads of either 3 min (EXT_3-min) or 8 min (EXT_8-min) duration. At the completion of each workload whole capillary blood samples were obtained for the determination of blood lactate (BLa) concentration (mM). Power output (Watts, W), HR and $\dot V{\rm O}_{\rm 2}$ were averaged in the final minute of each workload as well as in the third minute of the EXT_8-min. The workload, HR and $\dot V{\rm O}_{\rm 2}$ at the LT and OBLA were subsequently determined from the data of EXT_3-min and EXT_8-min. The results demonstrate that workload and $\dot V{\rm O}_{\rm 2}$ , but not HR, at the LT and OBLA were higher in the WT cyclists. At the same time, the workload at the LT obtained from the results of the EXT_3-min was significantly (P<0.05) higher then the value obtained in the EXT_8-min in the WT subjects but not the REC subjects. However, the workload, $\dot V{\rm O}_{\rm 2}$ and HR at the OBLA, together with the $\dot V{\rm O}_{\rm 2}$ and HR at the LT were not significantly different when calculated from data obtained from EXT_3-min or EXT_8-min. The data obtained in this study suggest that incremental exercise protocols using workloads of duration longer than 3 min have the effect of increasing the workload at the LT in well-trained cyclists. However, the OBLA determined in exercise tests using stage increments of either 3 min or 8 min is similar in cyclists of different training status.