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

Abstract

Valadão, Pedro Frederico, 2012. Effects of muscle action type on corticospinal excitability and triceps surae muscle-tendon mechanics. Department of Biology of Physical Activity, University of Jyväskylä. Master's Thesis in Biomechanics. 105 pp.The present study was designed to investigate corticospinal excitability modulation during maximum isometric and eccentric muscle actions with two different velocities. Moreover, the study aimed to clarify the effect of muscle action type on muscle-tendon mechanical behavior in order to shed light into the possible role of sensory information in modulating corticospinal excitability during different muscle actions. We compared motor evoked potentials (MEPs) to transcranial magnetic stimulation and Hoffman reflexes (H-reflex) in soleus muscle during isometric, slow eccentric (25 deg/s) and fast eccentric (100 deg/s) muscle actions. Concomitantly, ultrasonography was utilized to access soleus and medial gastrocnemius fascicle behavior, characterized by fascicle length, velocity and pennation angle.The main finding was that soleus H-reflex was depressed (P < 0.001) during both fast and slow eccentric protocols as compared to isometric, while no differences in fascicle length (P = 0.569) and pennation angle (P = 0.293) were found among the three protocols.Furthermore, although the fast eccentric protocol had a greater fascicle velocity than slow eccentric (P < 0.05), there were no differences in H-reflex (P > 0.05). No differences in MEP sizes were found among the three protocols (P = 0.750), while absolute silent period was significantly shorter (P = 0.009) for both eccentric protocols as compared to isometric.Taken together, the present results corroborates with the idea that the central nervous system has an unique activation strategy during eccentric muscle actions , Enoka 1996, and further refutes the hypothesis that sensory information plays an important role in modulating these actions.

Effects of eccentric versus concentric contractions of the biceps brachii on intracortical inhibition and facilitation

“…Furthermore, Duclay et al and Gruber et al showed that ECC contractions elicited greater modulation of corticospinal excitability from supraspinal centers (ie, enhanced motor cortical excitability and reduced spinal excitability) when compared to isometric or CON contractions . By contrast, Valadao et al showed no difference in corticospinal excitability between a single session of maximal isometric contractions and ECC contractions at fast or slow contraction velocities of the triceps surae muscle. The authors did, however, report a significant reduction in the cortical silent period duration following both ECC contraction conditions, when compared to isometric contractions.…”

Corticospinal excitability of tibialis anterior and soleus differs during passive ankle movement

“…Isotonic movements modify corticospinal excitability, such that excitability tends to be lower during lengthening relative to shortening and isometric contractions (Abbruzzese et al 1994; Gruber et al 2009; Duclay et al 2014), which seems to depend on the amount of Ia afferent feedback (Doguet et al 2017). However, elucidating the direct effect of muscle length-related feedback on the corticospinal tract output during dynamic contractions is challenging due to the influence of postsynaptic control mechanisms (Valadão et al 2018; Barrué-Belou et al 2018), and potential differences in neural drive that can influence neurophysiological responses (Abbruzzese et al 1994; Morita et al 2000).…”

Influence of fascicle strain and corticospinal excitability during eccentric contractions on force loss

“…Valadão, Kurokawa, Finni, and Avela () have recently reported a reduced neural activation (i.e. MEP/M, CSP and H reflex) of soleus muscle during maximal eccentric plantar flexions when compared with maximal isometric contractions, without differences in mechanical variables (i.e.…”

“…Hence, it seems that corticospinal inhibitions that occurred at long muscle lengths during eccentric contractions were not, at least directly, related to the extent of tension generated or fascicle stretching. Valadão, Kurokawa, Finni, and Avela (2018) As previously done by Ando et al (2018), we used two ultrasound probes attached in series to perform wider examination of the muscle architecture. Using this procedure, the width of the total scanned field reached 115 mm (including a 15 mm gap in the middle), which allowed us to scan full-size fascicles.…”