Analysis Of The Human EEG During Sustained Maximum Voluntary Contraction

Exercise-induced muscle fatigue one of important fields in sports research. Although many studies have addressed fatigue mechanisms at the muscular and peripheral neuromuscular systems, little knowledge is known regarding activity of the central nervous system (CNS), especially the brain, during fatigue. With the development of non-invasion technique since 1950s', there were some new and accurate measures to study the structure and function of brain.The paper describes detailed fatigue-related human brain cortex activation information during sustained maximum voluntary contraction with simultaneously recorded EEG data. Before analyzing the EEG data, EEG Complexity Analysis Software is developed.Human brain is a non-linear dynamics system that is so complex and self-organized. Presently, the EEG software, installed in EEG equipment, only includes the basic functions such as frequency analysis generally without any function modules about complexity analysis. Based on the original EEG software, EEG Complexity Analysis Software is developed for appending new functions to original software and further research. The software includes two modules. The first module is developed on C + + Builder, and mainly focuses on the fractal geometry dimension (FGD) and other basic functions. With highly independence, the module is easy to install in common computers. The second module is based on Matlab programs for analyzing EEG data, including the function of FGD, Lempel-Ziv (LZ), Cl and C2 designed by Jinghua Xu and so on.EEG signal is studied during muscle fatigue induced by sustained maximum voluntary contractions. After EEG signal is recorded, EEG complexity analysis software analyzes it in some indexes such as relative power of brain waves and non-linear (LZ,FGD) in sport and sense-relative brain cortexes. In this way, the correlation between muscle fatigue and CNS is discussed by analyzing the character of the indexes, so the CNS modulatory mechanism.Six healthy male subjects were instructed to produce and maintain 100% of maximum voluntary contraction (MVC) for 3 minutes using a hand grip instrument with simultaneously recorded EEG data. Before that, EEG signal is recorded continuously for 2 minutes during rest period.The exercise period is divided into 4 levels(ls, 60s, 120s, 180s) which are analyzed with the relative power of brain wave, LZ and FGD. The result shows that 91 wave of C3, C4, 01 areas increases firstly and then decreases during sustained MVC, but declines continuously in P4. In sensorimotor cortex (T3), LZ increases flatly while LZ increases and then decreases in sport and sense-relative brain areas (C3, Fz). The change of EEG complexity may relate to the non-linear modulation of nervous systems.The results have shown that some linear and non-linear characters of EEG data may change regularly with exercise-induced muscle fatigue developing. Above all, the study furthers the research about the correlation between nervous system and fatigue, and provides new scientific approaches for proving up the physiological mechanism of muscle fatigue.