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Selected Publication:
Kemper, D.
Spinal and corticospinal excitability before and after passive stretch of human plantar flexor muscles
Humanmedizin; [ Diplomarbeit ] Graz Medical University; 2018. pp. 77
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- Authors Med Uni Graz:
- Advisor:
- Christova Monica
- Gallasch Eugen
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- Abstract:
- Background: The established method to investigate influences of stretching on corticospinal excitability is the assessment of amplitudes of motor evoked potentials (MEP). The spinal excitability is investigated by comparison of amplitudes of stretch-reflex (T-reflex) and by the analysis of the H/M ratio. In a previous study of the same project, the influence of one minute stretching was already investigated and showed no effect on MEP, but inhibition of T-reflex and facilitation of H-reflex (Hoffmann’s reflex). Aim of this study was to investigate whether a longer duration of 5 minutes static stretching of soleus muscle (SOL) affects MEP, T-reflex and H-reflex. Methods: 17 healthy volunteers came on two testing days (control vs. stretching condition). The three assessments (T-reflex, H-reflex and MEPs) were carried out on right SOL at 4 time points: Before (Pre), and 3 times after 5 min (5x60s) passive static stretching at individual maximal ankle dorsiflexion (0, 5 and 10 minutes after). On the day of control condition without stretching, but 5 min rest instead. MEPs were obtained using transcranial magnet stimulation. Reflexes and MEPs were recorded by surface electromyography. In order to find significant differences between the time points, a Friedman repeated measures analysis of Variance and a Wilcoxon signed rank test were performed. Results: A significant (p=0.001) decrease in the amplitude of T-reflex was found immediately after and 5 min after stretching intervention and returned to baseline values after 10 min. Friedman ANOVA for H/M ratio, MEP amplitudes, MEP/Mmax ratio and MEP latency showed no significant differences (p>0.050) before and after stretch. Conclusion: It has been shown that there is a presynaptic inhibition of T-reflex lasting at least 5 min, but no effect on H-reflex. The unchanged cortical parameter (MEP) indicates that the influence on the a-motor neuron is rather unlikely.