Abstract
Purpose: The mechanisms involved in the coordination of muscle activity are not completely known: to investigate adaptive changes in human motor cortex Transcranial magnetic stimulation (TMS) was often used. The sport models are frequently used to study how the training may affect the corticospinal system excitability: Karate represents a valuable sport model for this kind of investigations for its high levels of coordination required to athletes. This study was aimed at examining possible changes in the resting motor threshold (rMT) and in the corticospinal response in karate athletes, and at determining whether athletes are characterized by a specific value of rMT.Methods: We recruited 25 right-handed young karate athletes and 25 matched non-athletes. TMS was applied to primary motor cortex (M1). Motor evoked potential (MEP) were recorded by two electrodes placed above the first dorsal interosseous (FDI) muscle. We considered MEP latencies and amplitudes at rMT, 110% of rMT, and 120% of rMT.Results: The two groups were similar for age (p > 0.05), height (p > 0.05) and body mass (p > 0.05). The TMS had a 70-mm figure-of-eight coil and a maximum output of 2.2 T, placed over the left motor cortex. During the stimulation, a mechanical arm kept the coil tangential to the scalp, with the handle at 45° respect to the midline. The SofTaxic navigator system (E.M.S. Italy, www.emsmedical.net) was used in order to correctly identifying and repeating the stimulation for every subject. Compared to non-athletes, athletes showed a lower resting motor threshold (p < 0.001). Furthermore, athletes had a lower MEP latency (p < 0.001) and a higher MEP amplitude (p < 0.001) compared to non-athletes. Moreover, a ROC curve for rMT was found significant (area: 0.907; sensitivity 84%, specificity 76%).Conclusions: As the main finding, the present study showed significant differences in cortical excitability between athletes and non-athletes. The training can improve cortical excitability inducing athletes' modifications, as demonstrated in rMT and MEP values. These finding support the hypothesis that the sport practice determines specific brain organizations in relationship with the sport challenges.
Highlights
Motor training and professional experience lead to great changes in the brain (Penhune and Steele, 2012; Hardwick et al, 2013; Dai et al, 2016)
The aim of this study was to verify whether Karate athletes have a different resting motor threshold and corticospinal response (MEP) compared to controls
Using Receiver Operating Characteristic (ROC) curve, we investigated if athletes are characterized by a specific value of resting motor threshold (rMT)
Summary
Motor training and professional experience lead to great changes in the brain (Penhune and Steele, 2012; Hardwick et al, 2013; Dai et al, 2016). As previously described in many electrophysiological studies, activation patterns of neurons in different brain areas are related to various cortical networks after long-term training (Fourkas et al, 2008; Wei and Luo, 2010; Schlaffke et al, 2014). Observing action of dancing with the mirror systems, it was described that the trained athletes showed greater bilateral activations in motor-related cortical areas (CalvoMerino et al, 2005). In classic TMS experiments, motor evoked potentials (MEPs) from muscles activities are recorded thanks to electromyographic (EMG) electrodes after stimulation of the primary motor cortex (M1). The threshold intensity can be defined as the intensity that evokes MEPs of a given amplitude during consecutive trials in a muscle. The intensity of TMS can be set to a percentage of this threshold intensity, but, since it is different for every subject, a measurement of this threshold has to be done (Wassermann, 1998)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
