Effect of a Reduced Base of Support in Standing and Balance Training on the Soleus H-reflex

Autor:	David M. Koceja, Mark H. Trimble
Rok vydání:	2001
Předmět:	Adult Reflex Stretch Time Factors Posture Electromyography H-Reflex medicine Postural Balance Humans Stretch reflex Muscle Skeletal Soleus muscle medicine.diagnostic_test Teaching General Neuroscience Motor control General Medicine Anatomy Adaptation Physiological Sagittal plane medicine.anatomical_structure Anesthesia Reflex H-reflex Psychology
Zdroj:	International Journal of Neuroscience. 106:1-20
ISSN:	1543-5245 0020-7454
DOI:	10.3109/00207450109149734
Popis:	The present study provides evidence that a reflex at the segmental level can adapt over a two hour experiment in a functionally appropriate manner in response to a balance training task. Subjects (N=9) received soleus (S) H-reflexes in blocks of seven trials while free standing on a normal base-of-support (NBOS) and while standing on a plafform with a reduced base-of-support (RBOS) in the sagittal plane. During the RBOS condition, the H-reflex served as a postural perturbation. Subjects were instructed to suppress the H-reflex when it was evoked, as an attempt to maintain a balanced state. Background EMG from the S and tibialis anterior muscles, the S M-wave, and stimulus current were maintained at a constant level during the experiment. Subjects initially received a block of NBOS trials, followed by 4 RBOS blocks (training), a second NBOS block, four additional RBOS blocks, and a third NBOS block with the protocol repeated on three different days (D1, D2 and D3) within the same week. The S H/M ratio was depressed 9% upon standing on the RBOS. With training the S H/M ratio decreased by 22% on Dl, 18% on D2 and 6% on D3. The ratio between the H-reflex and background S EMG (H-reflex gain) decreased 10% on D1, 40% on D2 and 23% on D3 when the first NBOS and first RBOS blocks were compared. Due to a slight increase in the S EMG across blocks, the H-reflex gain decreased considerably more across blocks than the H/M ratio. Although the S H/M ratio underwent an 7% decrease from D1 to D3, the differences were not significant. Individually, however, six of the nine subjects decreased their H/M ratios from 12-42% across days. The results may reflect the inception of longer-term adaptations of the segmental stretch reflex system.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_dedup___::fb8e879278bd5e3aeb06d76801af50f9 https://doi.org/10.3109/00207450109149734 Zobrazit plný text záznamu Plný text ve formátu PDF Plný text ve formátu HTML
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