Invariable H-reflex and sustained facilitation of stretch reflex with heightened sympathetic outflow

Kamibayashi, Kiyotaka; Nakazawa, Kimitaka; Ogata, Hisayoshi; Obata, Hiroki; Akai, Masami; Shinohara, Minoru

doi:10.1016/j.jelekin.2008.11.002

« Previous Next »Journal of Electromyography and Kinesiology
Volume 19, Issue 6 , Pages 1053-1060, December 2009

Invariable H-reflex and sustained facilitation of stretch reflex with heightened sympathetic outflow

Kiyotaka Kamibayashi
- Department of Rehabilitation for Movement Functions, Research Institute, National Rehabilitation Center for Persons with Disabilities, 4-1 Namiki, Tokorozawa, Saitama 359-8555, Japan
- Corresponding author. Tel.: +81 4 2995 3100; fax: +81 4 2995 3132.
- Present address: Graduate School of Systems and Information Engineering, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573, Japan. Tel./fax: +81 29 853 5766.
Kimitaka Nakazawa
- Department of Rehabilitation for Movement Functions, Research Institute, National Rehabilitation Center for Persons with Disabilities, 4-1 Namiki, Tokorozawa, Saitama 359-8555, Japan
Hisayoshi Ogata
- Department of Rehabilitation for Movement Functions, Research Institute, National Rehabilitation Center for Persons with Disabilities, 4-1 Namiki, Tokorozawa, Saitama 359-8555, Japan
Hiroki Obata
- Department of Rehabilitation for Movement Functions, Research Institute, National Rehabilitation Center for Persons with Disabilities, 4-1 Namiki, Tokorozawa, Saitama 359-8555, Japan
Masami Akai
- Department of Rehabilitation for Movement Functions, Research Institute, National Rehabilitation Center for Persons with Disabilities, 4-1 Namiki, Tokorozawa, Saitama 359-8555, Japan
Minoru Shinohara
- School of Applied Physiology, Georgia Institute of Technology, Atlanta, GA, USA
- Atlanta VA Rehabilitation Research & Development Center of Excellence for Aging Veterans with Vision Loss, Decatur, GA, USA

Received 10 July 2008; received in revised form 25 September 2008; accepted 5 November 2008. published online 22 December 2008.

Abstract

Stretch reflex shows sustained (3-min) increase with heightened sympathetic outflow [Hjortskov N, Skotte J, Hye-Knudsen C, Fallentin N. Sympathetic outflow enhances the stretch reflex response in the relaxed soleus muscle in humans. J Appl Physiol 2005;98:1366–70], but it is unknown if it accompanies a sustained increase in H-reflex. The purpose of the study was to test if there is a sustained facilitation in the H-reflex in the human soleus muscle during a variety of sustained tasks that are known to elevate sympathetic outflow. Mean arterial blood pressure, heart rate, and H- and stretch reflexes in the relaxed soleus muscle were obtained in healthy young adults who performed mental arithmetic, static handgrip exercise, post-handgrip ischemia, and cold stimulation. Each task lasted 3min with a 3-min rest in between tasks. Data were analyzed for the initial 30s and entire 3min of each task. There was a heightened cardiovascular response in all tasks for both durations of analysis. An increase in H-reflex amplitude was not observed for either the initial or entire duration of the analysis. The tasks increased stretch reflex amplitude for both durations of analysis. Invariable H-reflex and sustained facilitation of stretch reflex with heightened sympathetic outflow would imply sympathetic modulation of muscle spindle sensitivity.