Abstract des Autors

The aim of this study was to evaluate electroencephalographic (EEG) changes within a graded bicycle ergometry of increasing and decreasing workload. EEG was recorded at rest, after each step and after 15 and 30 min of recovery. Significant increases in electroencephalographic spectral power of all frequency bands, heart rate, lactate and ammonia concentration were measured through the test design. Anaerobic workloads at the beginning of the test showed significantly increased frontal beta power due to a higher attentional level in comparison to the same intensities at the end of the test. Within the test of increasing workload spectral power density reflected quantitative topographical changes for the faster frequency bands (alpha, beta) with lowest power density in the alpha-2 frequency band after warm up. Additional workload of aerobic intensity revealed highest increases parietally in the alpha-1 frequency band. Anaerobic workload led to more pronounced increases in fronto-central and parietal areas of the alpha-2 frequency band and centrally located increases (predominantly Cz) in the beta frequency bands as sign of activation of the motorical specific and the somatosensorical cortical regions reflecting the high grade of physical demand. Negative correlations of ammonia and the percentual change in the alpha-2 power after anaerobic workload may indicate a central fatigue reaction in response to peripheral signals of exhaustion. In conclusion aerobic and anaerobic workload within a graded bicycle ergometry led to different effects in EEG with influence of the step sequence on the attentional level of the frontal cortex. Verf.-Referat