Article

Concentric and eccentric muscle contractions have distinct differences in their
neuromuscular and neurophysiologic characteristics. However, although many
evidences regarding the features of these types of muscle contraction have
emerged, there have been few neuroimaging studies to compare the two types of
contractions. Therefore, we investigated whether cortical activity associated
with eccentric contraction of the wrist extensors differed from that of
concentric contraction, using functional MRI (fMRI). Fifteen right-handed healthy
subjects were enrolled in this study. During 4 repeating blocks of eccentric and
concentric muscle contraction paradigms, the brain was scanned with fMRI. The
differences in the BOLD signal intensities during the performance of eccentric
and concentric exercise were compared in the predetermined regions of interest.
Our findings revealed that many cortical areas associated with motor performance
were activated, including the primary motor area, the inferior parietal lobe, the
pre-supplementary area (pre-SMA), the anterior cingulate cortex, the prefrontal
area, and the cerebellum. In addition, lower signal intensities were seen in the
right primary motor cortex and right cerebellum during eccentric contractions
compared with concentric contractions, whereas higher signal intensities were
detected in other cortical areas during eccentric contractions. In the study, we
demonstrated that eccentric and concentric muscle contractions induced quite
different patterns of cortical activity respectively. These findings might be
attributed to different strategy of neuro-motor processing and a higher level of
cognitive demand for the performance of motor task with a higher degree of
difficulty such as that required during eccentric contractions in comparison of
concentric contractions.

Langue : ANGLAIS