مرکز منطقه ای اطلاع رساني علوم و فناوري - H بررسي ميزان تاثير تغيير وضعيت مفصل ران بر روي فعاليت رفلكس

چكيده لاتين :

The aim of this study was to assess the effects of hip position on H reflex amplitude. This study was carried on 30 healthy female subjects. Their ages ranged from 20 to 40 years. In this experiment, after placing the recording electrodes on the soleus muscle of the dominant leg, the lower limb from hip joint was randomly positioned in 15°, 40° flexion, 20° abduction and 20° extension. H reflexes in five stages of stimulus intensity and maximum M wave (Mmax) were recorded by stimulation of tibial nerve in the popliteal fossa. In addition, latency of H reflexes in five stages, latency of maximum M wave and HIM ratio in four position were also recorded. In this study, knee joint was extended and ankle joint was fixed in 90° (neutral position) by a metal plate which was designed at the end of the bed. The lower limb, was also fixed by a sling in the femoral region. Paired t-test and ANOVA were used to determine significant differences between variables. Results were as follows: amplitude of H reflex in five stages of stimulus intensity and H/M ratio were decreased from 15° flexion (control position) to 40° flexion and increased from control position to 20° extension. In 20° abduction, amplitude of H reflex was decreased only in third, forth and fifth stages of experiment. HIM ratio was also decreased but not singnificantly. Amplitudes of Mmax werenʹt differed in all positions which indicating test procedure were the same. The effects of hip position on H reflex amplitude and HIM ratio could explained by changing the activity of muscular and skin receptors and Golgi tendon organs and their effects on motor neuron pools. Positioning of the hip joint causes change in activity and excitability in motor neuron pools in spinal cord. These changes are due to genetic background and type of activity can decrease (inhibition) or increase (excitation) motor neuron activity in spinal cord.