B-22: Free Communication/Poster – Exercise Testing: Older Adults, General Testing, Acute Exercise Responses: WEDNESDAY, JUNE 1, 2005 2:00 PM - 5:00 PM ROOM: Ryman C1
Studies of exercise performance typically use methods in which outcome variables are sampled at distinct time points and then either averaged over the course of the trial or reported at these time periods. Studies which have sampled more frequently have found that measured variables ‘oscillate’ in an apparently random fashion. We have recently suggested that these variations are the result of a centrally controlled, feedforward system which regulates the pacing strategy in anticipation of the development of bodily harm during exercise. That is, they are not randomly occurring, but are deterministic and can be mathematically modelled.
To mathematically model pacing strategy (power output) during selfpaced 20 km cycling time-trials.
Eleven well-trained cyclists performed a 20 km cycling time-trial, during which power output was sampled every 200 m. Spectral analysis was performed to obtain a power spectrum for the trials, and a fractal dimension was calculated for the trials using the Higuchi method.
Power output was maintained throughout the trial until the final kilometre, when it increased significantly, indicating the presence of a global pacing strategy. The power spectrum revealed the presence of multiple peaks during trials, with the position of the peaks changing over the course of the trial. The fractal dimension (D-score) was similar for all subjects over the 20 km trial.
The presence of multiple peaks indicates that the global pacing strategy consists of multiple, simultaneously occurring strategies, and the shift of these peaks during the trials suggests that there are alterations in the underlying dynamic system that regulates pacing strategy. The measured oscillations are thus not random or irregular, but can be modelled and are deterministic in nature.