Differential modulation of motor cortex plasticity in skill- and endurance-trained athletes
Extensive evidence exists that regular physical exercise offers neuroplastic benefits to the brain. In this study, exercise-specific effects on motor cortex plasticity were compared between 15 skilled and 15 endurance trained athletes and 8 controls.
Plasticity was tested with a paired associative stimulation (PAS) protocol. PAS is a non-invasive stimulation method developed to induce bidirectional changes in the excitability of the cortical projections to the target muscles. Motor cortex excitability was assessed by motor-evoked potentials (MEPs) in the task-relevant soleus muscle, elicited with transcranial magnetic stimulation, before and following PAS. To test for changes at the spinal level, soleus short latency stretch reflexes (SLSR) were elicited before and after PAS.
PAS induced a significant (76 ± 83 %) increase in MEP amplitude in the skill group, without significant changes in the endurance (−7 ± 35 %) or control groups (21 ± 30 %). Baseline MEP/post MEP ratio was significantly different between the skill and endurance groups. SLSR remained unchanged after the PAS intervention.
The possible reason for differential motor cortex plasticity in skill and endurance groups is likely related to the different training-induced adaptations. The findings of the current study suggest that long-term skill training by skill group induced preferable adaptations in the task-related areas of the motor cortex because increased plasticity is known to enhance motor learning.
KeywordsPhysical activity Training adaptation Motor cortex Brain plasticity Paired associative stimulation
Maximal voluntary contraction
Paired associative stimulation
Resting motor threshold
Short latency stretch reflex
Transcranial magnetic stimulation
The authors are very grateful to the subjects who participated in the study and to the laboratory staff from the Neuromuscular Research Center (Department of Biology of Physical Activity) of the University of Jyväskylä, Finland, for their valuable contributions to this project.
Conflict of interest
The authors declare no conflict of interest.
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