en Experimental research article Experimental research article Introduction : There are different applications for cooling in rehabilitation and there is also a controversy in results of applying ice on limb and its effects on motorneurons excitability. Methods : This study was done to determine the effect of applying controlled cooling (rubbing cold ointment with 3°C temperature) on the spinal skin (around T place of S root nerve) on the excitability of soleus 11, 11 motorneurons in ten healthy, non-athletic men. Each volunteer was tested in two [control (vazeline ointment with - environment temperature) and examination (cold vazeline)] separate sessions. We used soleus H-reflex and M h wave recruitment curve parameters for evaluation. Stimulation current was a square pulse with 700 microsecond duration and 0.2 Hz frequency. H-reflex was recorded with 9 different amplitudes. Results: Fit L slope, fit L slope and peak to peak amplitude of H-reflex decreased immediately and 30 3 5 minutes after the application of cold ointment. Conclusion: Cold by stimulating the thermoreceptors and reducing the firing rate of surface mechanoreceptors can decrease the excitability of motoneurons and this effect may be long lasting. Recruitment curve, H-reflex, cold, soleus, Motoneuron activity. 151 157 http://ppj.phypha.ir/browse.php?a_code=A-10-63-2&slc_lang=en&sid=1 Hossein Salehi 320031947532846002929 320031947532846002929 No Giti Torkaman torkamg@modares.ac.ir 320031947532846002930 320031947532846002930 Yes Seyed Mohammad Firoozabadi 320031947532846002931 320031947532846002931 No