Enhancement of spinal reciprocal inhibition depends on the movement speed and range of repetitive passive movement. (25th June 2020)

• Record Type: Journal Article
• Authors: Hirabayashi, Ryo; Edama, Mutsuaki; Kojima, Sho; Miyaguchi, Shota; Onishi, Hideaki
• Is Part Of: European journal of neuroscience. Volume 52:Number 8(2020)
• Page Start: 3929
• Page End: 3943
• Publication Date: 2020-06-25
• Subjects: electrical stimulation -- electromyograph -- H‐reflex -- joint movement -- M wave; Nervous system -- Periodicals; 612.8
• DOI: 10.1111/ejn.14855
• Languages: English
• ISSNs: 0953-816X

Abstract

Abstract: Repetitive passive movement (RPM) is a rehabilitation technique that increases spinal reciprocal inhibition (RI) as movement speed increases. However, characterization of the RPM number, frequency and range relative to the afferent impulses of muscle spindles and RI modulation has not been performed. In this study, we attempted to clarify these factors and evaluate their relationship to RI. We used 20 healthy adults for our first experiment (Experiment 1) and 16 healthy adults for our second experiment (Experiment 2). In Experiment 1, the RPM task was performed in the 80°–120° range for the ankle joint for 618 times at 80°/s (80°/s_618 times), 309 times at 160°/s (160°/s_309 times) and 618 times at 160°/s (160°/s_618 times). In Experiment 2, the RPM task focused on two ranges for the ankle joint (80°–100° and 100°–120°) and was performed at 160°/s with a movement time of 10 min. To measure RI, electrical stimulation was used to evoke a conditioning stimulus in the common peroneal nerve and the test stimulus in the tibial nerve. Conditions included the test stimulus only and conditioning stimulation–test stimulation intervals (CTI) of 2 and 20 ms. RI was measured before (Pre); immediately after; and 5, 10, 15 and 20 min after the task. Our findings suggest that the faster the movement speed of the RPM and the wider the movement range, the greater the increase in Ia firing. This may have enhanced RI by activating the inhibitory interneurons of RI. Abstract : Graphical abstract of RI enhancement by RPM. (1) RPM of the ankle joint. (2) Increased impulses from muscle spindles. (3) Increased frequency of firing of afferent Ia fibers. (4) Activity of Ia inhibitory and PAD interneurons. RI was enhanced by the activity of Ia inhibitory and PAD interneurons. RI, reciprocal inhibition; RPM, repetitive passive movement; Sol, soleus; TA, tibialis anterior; PAD, primary afferent depolarization; αMN, alpha‐motor neuron and Ia, afferent Ia fibers.