Effects Of Load, Fatigue And Magnetic Stimulation On EEG And EMG Signals During Lateralraise Task

The cerebral cortex controls the movement of body, and movement has a feedback effect on the cerebral cortex. The body is subjected to exercise load and fatigue, but the impact of the load and fatigue which effects on the muscle tissue and the motor cortex is not clear. Scalp electroencephalograph(EEG) is a common physiological analysis method used in the laboratory and clinic, it can be used to analyze the activities of the motor cortex. Surface electromyography(EMG) is the general reflect of the electrical activity of muscle tissue, it can reflect the muscle contraction strength and functional state. In addition, magnetic stimulation has the function of regulating nerve activity and changing tissue excitability, but the mechanism of magnetic stimulation is still not clear. In this study, we designed a lateral raise task to collect the scalp EEG and EMG signals, and extract the signal features to learn the effect of exercise load, fatigue and magnetic stimulation on human physiological signals.18 healthy right-handed male subjects were rectuited in the two experiments which was divided into task 1 and task 2. There were nine times lateral raising in task 1 with different weight of load, and took 5 minutes rest between each two raising. After being fully relaxed, the subjects started to raise right arm steadily and were asked to keep as long as possible. On the basis of task 1, magnetic stimulation was introduced to task 2. In task 2, the deltoid muscle of right side is stimulated to relieve fatigue. The frequency of magnetic stimulation was 6Hz, and the stimulation intensity was 35 m T. In task 1 and task 2, 32 channels EEG and two channel EMG were recorded. According to the time of the raising, the EEG and EMG signals were divided into non fatigue state and fatigue state. After the preprocessing of raw data, some signal features were analyzed. Root mean square, median frequency, and sample entropy were features of EMG. Spectrum integral, correlation coefficient and sample entropy were features of EEG. For cortical muscle coupling, the coherence between EEG and EMG signals was calculated. Through the calculation results and statistical analysis of the signal features, exercise load, fatigue and impact of magnetic stimulation were determined.In result, the features showed significant differences in various load and different fatigue state. When the weight of exercise load was increased, the root mean square and the median frequency of the EMG increased significantly, p<0.05. In fatigue state, the root mean square, median frequency and sample entropy of the EMG, the EEG sample entropy and coherence of C3 and CP5 electrode decreased significantly, p<0.05. After magnetic stimulation, Beta rhythm spectrum integral, correlation between cortex electrodes and the coherence of C4 electrode in fatigue state were improved significantly, p<0.05. While the mean valve of root mean square and median frequency decreased.In this paper features of EEG and EMG were calculated to analyze the impact of load and fatigue feedback. These could also provide experimental data for motion mechanism research. The evaluation of magnetic stimulation can help determine the appropriate parameters and stimulus pattern, so that promote the research and development of new magnetic stimulation device.