Greater Movement-Related Cortical Potential During Human Eccentric Versus Concentric Muscle Contractions

Abstract

Despite abundant evidence that different nervous system control strategies may exist for human concentric and eccentric muscle contractions, no data are available to indicate that the brain signal differs for eccentric versus concentric muscle actions. The purpose of this study was to evaluate electroencephalography (EEG)-derived movement-related cortical potential (MRCP) and to determine whether the level of MRCP-measured cortical activation differs between the two types of muscle activities. Eight healthy subjects performed 50 voluntary eccentric and 50 voluntary concentric elbow flexor contractions against a load equal to 10% body weight. Surface EEG signals from four scalp locations overlying sensorimotor-related cortical areas in the frontal and parietal lobes were measured along with kinetic and kinematic information from the muscle and joint. MRCP was derived from the EEG signals of the eccentric and concentric muscle contractions. Although the elbow flexor muscle activation (EMG) was lower during eccentric than concentric actions, the amplitude of two major MRCP components-one related to movement planning and execution and the other associated with feedback signals from the peripheral systems-was significantly greater for eccentric than for concentric actions. The MRCP onset time for the eccentric task occurred earlier than that for the concentric task. The greater cortical signal for eccentric muscle actions suggests that the brain probably plans and programs eccentric movements differently from concentric muscle tasks.

Effects of muscle action type on corticospinal excitability and triceps surae muscle-tendon mechanics

“…Corroborating with the present study, other authors have shown evidences that supraspinal excitability seems to be higher during eccentric muscle actions (Duclay et al 2011, Fang et al 2001, 2004Gruber et al 2009). Despite increased cortical excitability, the responsiveness of the SOL motoneuron pool is lower during eccentric muscle actions, indicating that changes in neural control of muscle activity occurs both at spinal and cortical sites.…”

Intracortical Inhibition Assessed with Paired-Pulse Transcranial Magnetic Stimulation is Modulated during Shortening and Lengthening Contractions in Young and Old Adults

“…Previous studies using electroencephalography (EEG) in young subjects have reported that movement related cortical potentials are greater during lengthening than shortening contractions [10,11], suggesting that reductions in inhibitory tone should be greatest during muscle lengthening. However, a more recent study using functional magnetic resonance imaging (fMRI) has localised this increased cortical activity during lengthening contractions to higher order motor areas, such as the pre-supplementary motor area and anterior cingulate cortex [9].…”

“…This includes observations that voluntary activation, electromyography (EMG), force generation and spinal motoneuron excitability are all different during lengthening contractions [1,2]. Furthermore, recent evidence from studies using a range of neurophysiological and neuroimaging techniques have provided compelling support for distinct patterns of cortical activity during lengthening contractions [3][4][5][6][7][8][9][10][11]. In addition, lengthening contractions are also associated with reduced motor performance [12][13][14].…”

Time to task failure of the contralateral untrained limb after high load-low repetition eccentric and low load-high repetition resistance training

“…Repeated recruitment of fast twitch motor units during eccentric training reduce their recruitment threshold 30 , and facilities their contribution to sustain force output during a fatiguing contraction. A longer time to task failure observed after eccentric training may also be related to higher cortical activation during eccentric exercise 18 , which in turn result in an enhanced neural drive in the corticospinal pathways to sustain muscle force. Moreover, eccentric training uniquely modulates neural regulatory pathways involved in the excitation and inhibition process and to a greater extent than concentric training 20,31,32 .…”

“…However, neural adaptions to resistance training are dependent on type of muscle contractions performed 15,16,17 . For example, previous studies reported greater cortical activities during eccentric task 18 , and a higher motor unit discharge rates after eccentric exercise as compared to concentric exercise 19 . Moreover, improvements in maximal muscle force, peak torque and muscle hypertrophy after eccentric training was significantly larger than those observed after concentric training 16,20 .…”