RESEARCH REPORT POSTER DISPLAY

EFFECTS OF JOINT TRACTION OF UPPER LIMB ON SOLEUS H-REFLEX IN MAN. Koyama T¹, Yanagisawa K², Aizawa J³; ¹Department of Physical Therapy, Surugadai Nihon University Hospital, Tokyo, Japan. ²Faculty of Health Sciences, Tokyo Metropolitan University, Tokyo, Japan. ³Department of Rehabilitation, Tokyo Medical and Dental University Hospital, Tokyo, Japan

PURPOSE: Joint traction is used to increase range of motion and muscle strength, or to reduce joint pain in physical therapy. Traction also acts as a stretch stimulus by elongating the muscles. It is not certain what influence the traction of the upper limb facilitates on the motoneuron of the lower limb. The purpose of this study is to examine the effects of joint traction of upper limb on soleus H-reflex. RELEVANCE: This study relates to the physiological evidence base of physical therapy. PARTICIPANTS: Sixteen healthy male subjects who had no orthopedic or neurological disease, ranging in age from 20 to 28 years, participated in this study. This study was approved by the Ethics Board of Tokyo Metropolitan University, and written informed consent was obtained from all subjects before testing. METHODS: In supine position, the subjects were passively kept at upper limb neutral position and the combined position that was 30° extended, 20° abducted, 70° internal rotated position of the shoulder respectively, and their upper limb was pulled distally by a pulley. Traction force was set to four kinds of loads (no-load, 3kg, 6kg and 9kg). The combined position was used as one of the starting positions of motion patterns in proprioceptive neuromuscular facilitation (PNF) approach. Derivation of soleus H-reflex was performed to record to electromyography (NEUROPACK II+, Nihon Kohden inc, Japan) using surface electrodes with trancecutaneus stimulation to tibial nerve. Stimulus intensity was set to 1.12 fold of H-reflex threshold. Single-square wave, 1 msec pulses, 1 Hz were delivered by a stimulator. Averaging of 32 pulses was measured as H-reflex amplitudes (peak to peak) at each testing position. ANALYSIS: A two-factor (two upper limb positions × four kinds of traction force) with repeated measure ANOVA was used to identify significant effects. All data analyses were performed using SPSS for windows 13.0 (SPSS Inc, Chicago). Level of statistical significance was set at the 0.05 alpha level. RESULTS: The traction of upper limb significantly increased the amplitude of the soleus H-reflex. There were no significant differences between the two positions, and no interaction between positions and traction forces. Multiple comparisons showed that traction of 6kg and 9kg significantly increased H-reflex amplitudes compared with no-load. CONCLUSIONS: This finding suggests that the traction of upper limb might influence the excitability of soleus motoneuron, and that the more traction force is increased, the more the excitability enhanced. IMPLICATIONS: This result may be the physiological base that can be applied to facilitation approach to the lower limb. KEYWORDS: joint traction, motoneuron, soleus H-reflex. FUNDING ACKNOWLEDGEMENTS: None.

ETHICS COMMITTEE: the Ethics Board of Tokyo Metropolitan University