摘要：The purpose of this study was to assess measures of the time taken for subjects of different training status to reach steady-state VO_2, using a traditional data processing model and a new model. Two groups of subjects were recruited: an untrained (UT) (n = 7), and a highly-trained (HT) cyclist group (n = 9). Following a maximal cycling test to exhaustion to ascertain ventilation threshold (VT), each subject underwent two cycling trials. Trial 1 consisted of an exercise transition to 85% VT. Trial 2 involved a transition to 35% VT for 6 min, followed by a 2nd transition to 85% VT. 3-breath averaged data were fit using the traditional mono-exponential model to ascertain both tau and 4xtau, and using a new method (TTSS) to derive the time taken to reach steady-state. 4xtau (4τ) and TTSS values were statistically analyzed for comparison and validity of tau. As well, differences in tau and TTSS values between the groups were assessed. There were significantly lower values for TTSS compared to 4τ for all trials. For the 85% VT exercise transitions, TTSS remained invariant between both trials. However, 4τ increased significantly for the transition from a baseline compared to the transition from unloaded cycling. These results indicate a necessity to propose new methods of VO_2 kinetics data processing.
