Greater movement-related cortical potential during human eccentric versus concentric muscle contractions

Despite abundant evidence that different nervous system control strategies may exist for human concentric and eccentric muscle contractions, no data a re available to indicate that the brain signal differs for eccentric versus concentric muscle actions. The purpose of this study was to evaluate elect roencephalography (EEG)-derived movement-related cortical potential (MRCP) and to determine whether the level of MRCP-measured cortical activation dif fers between the two types of muscle activities. Eight healthy subjects per formed 50 voluntary eccentric and 50 voluntary concentric elbow flexor cont ractions against a load equal to 10% body weight. Surface EEG signals from four scalp locations overlying sensorimotor-related cortical areas in the f rontal and parietal lobes were measured along with kinetic and kinematic in formation from the muscle and joint. MRCP was derived from the EEG signals of the eccentric and concentric muscle contractions. Although the elbow fle xor muscle activation (EMG) was lower during eccentric than concentric acti ons, the amplitude of two major MRCP components-one related to movement pla nning and execution and the other associated with feedback signals from the peripheral systems-was significantly greater for eccentric than for concen tric actions. The MRCP onset time for the eccentric task occurred earlier t han that for the concentric task. The greater cortical signal for eccentric muscle actions suggests that the brain probably plans and programs eccentr ic movements differently from concentric muscle tasks.