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Spinal Cord and Reflexes
Published in Nassir H. Sabah, Neuromuscular Fundamentals, 2020
The second part of the chapter is concerned with explaining the general features of spinal reflexes, followed by a detailed consideration of the flexion reflex, the stretch reflex, and the tendon organ reflex, including supraspinal influences. The chapter ends by considering reflexes elicited by stimulation, namely, the H-Reflex and the tonic vibration reflex.
Whole-body vibration training
Published in Claudio F. Donner, Nicolino Ambrosino, Roger S. Goldstein, Pulmonary Rehabilitation, 2020
Effects of WBVT can be divided into acute and chronic effects. An increase in lower extremity blood circulation (7), improvement of muscle performance and balance (8) as well as an increase in human growth hormone output (9) have been observed after just a single bout of WBVT. Chronic effects of WBVT have been reported in various physiological systems. A central mechanism of WBVT is elicited by the ‘tonic vibration reflex’ that provokes muscle contractions especially in the lower extremities (10). This reflex caused by mechanical vibration induces a higher rate of motor unit recruitment in skeletal muscles by stimulating muscle spindles and Golgi cells. It is supposed that the most important structural benefits of WBVT are of neurophysiological origin (11). Other possible mechanisms of WBV benefits include enhanced postural control, balance performance and improved inter-muscular coordination like the complex interplay of agonists and antagonists (12,13). WBVT has also been shown to be an effective training modality to counteract immobility-related muscle atrophy and loss of bone density (14).
‘Eppur si move’: The Association Between Electrophysiological and Psychophysical Signatures of Perceived Movement Illusions
Published in Journal of Motor Behavior, 2018
Michela Balconi, Davide Crivelli, Marco Bove
Participants placed their right arm behind a wooden screen so that they could not see it, and wore an adjustable wrist splint. The splint was designed to keep the wrist angle fixed at 10°. Such slightly extended posture was induced to better expose wrist tendons and to make the placement of the stimulator easier while keeping the wrist joint as relaxed as possible. A surface vibratory stimulator was then placed over the forearm 2–3 cm below the right wrist joint and the stimulation was applied perpendicularly with respect to the wrist flexor carpi radialis muscle tendon, so to induce the illusion of wrist/hand extension movements. The stimulator (VP200, Techno Concept—Dynatronic, Mane, France) was set at a frequency of 90 Hz with vibration amplitude of 1 mm. To keep track of potential experimental biases due to tonic vibration reflexes, the activity of the flexor carpi radialis muscle has been continuously monitored by a surface electromyography system. All trials containing muscular tonic vibration reflex artifacts were not considered in data analyses.
Whole body vibration improves maximum voluntary isometric contraction of knee extensors in patients with chronic kidney disease: A randomized controlled trial
Published in Physiotherapy Theory and Practice, 2019
Helen K. Fuzari, Armèle Dornelas de Andrade, Marco A Rodrigues, Ana I Medeiros, Maíra F Pessoa, Amina M. Lima, Mikhail S. Cerqueira, Patrícia E. Marinho
In the vibration, muscle spindles are the first sensory structure activated, followed by Golgi tendon organs and type I and type II joint mechanoreceptors. Vibratory stimuli initially act on these three sensory structures, hypersensitizing the gamma (γ) system and leading to a contraction reflex called tonic vibration reflex, which recruits the motor units through the polysynaptic pathway. Parallel to this recruitment, maintenance of the vibratory stimulus leads motor units that are already in operation to derecruitment through a presynaptic inhibition mechanism with consequent reduction of the monosynaptic reflexes, so that the muscle tends to reduce its reflex stretch, improving contraction by synchronizing the motor units (Bogaerts et al., 2011).
Comment to paper by Moggio et al “vibration therapy role in neurological diseases rehabilitation: an umbrella review of systematic reviews”
Published in Disability and Rehabilitation, 2022
Nicoletta Manzo, Claudia Celletti, Antonella Conte, Filippo Camerota
Finally, the authors stated that the structural adaptation due to the vibratory stimulus is initiated by the stimulation of the tonic vibratory reflex. However, most of the available studies using the fMV have been performed by applying very low amplitude vibration, that is insufficient to produce a tonic vibration reflex [16]. Thus, it remains still controversial whether tonic vibration reflex activation is needed in order to induce clinical effects.