اثر فوري و بلندمدت اسپري سردكننده بر متغيرهاي ميوالكتريكي عضلات منتخب اندام تحتاني پاي برتر حين اجراي فرود-پرش تك‌پا

Immediate and Long-Term Effect of Cold Spray on Myoelectric Variables of Selected Muscles of Lower Extremity of Dominant Leg during Single-Leg Drop-Jump

سرمادهي يك مداخلۀ فوري و مؤثر حين ايجاد آسيب‌هاي حاد ورزشي است. نتايج مطالعات پيشين در زمينۀ شناسايي تأثيرات سرمادهي بر متغيرهاي ميوالكتريكي عضلات اندك و متناقض‌اند. هدف از مطالعۀ حاضر، بررسي اثر فوري و بلندمدت (20 دقيقه بعد) استفاده از اسپري سردكننده در بخش قدامي- داخلي مفصل زانوي پاي برتر، بر متغيرهاي ميوالكتريكي عضلات منتخب اندام تحتاني بود. پانزده مرد سالم داوطلبانه در اين تحقيق شركت كردند. از آزمون آماري آناليز واريانس با اندازه‌هاي تكراري براي تجزيه‌وتحليل داده‌ها استفاده شد. كاهش معناداري در ميزان فعاليت عضلۀ نيم‌وتري (بلافاصله و 20 دقيقه پس از سرمادهي) و دوقلوي داخلي (بلافاصله پس از سرمادهي) در فاز پيش‌فعاليت، نيم‌وتري (بلافاصله پس از سرمادهي) در فاز اكسنتريك، و افزايش معناداري در ميزان فعاليت عضلۀ پهن‌داخلي در فاز كانسنتريك (بلافاصله پس از سرمادهي) مشاهده شد (0/05>P). همچنين، كاهش معناداري در مقدار فركانس ميانۀ عضلۀ درشت‌نئي قدامي (بلافاصله پس از سرمادهي) مشاهده شد (0/05>P). هيچ تفاوت معناداري در هر 3 فاز حركت بين ميزان هم‌انقباضي عضلات مفصل زانو مشاهده نشد (0/05

Cryotherapy is used as an immediate effective treatment for acute sport injuries. The results of former studies about the effects of cryotherapy on myoelectric variables of muscles were slight and contradictory. The aim of the present study was to investigate immediate and long-term (20 min. later) effect of cold spray in anterior-medial area of the knee joint of dominant leg on myoelectric variables of selected muscles of lower extremity. 15 health men voluntarily participated in this study. ANOVA with repeated measures was used for data analysis. A significant decrease in semitendinosus activity (immediately and 20 min. after cryotherapy) and medialis gastrocnemius (immediately after cryotherapy) in pre-activation phase, semitendinosus (immediately after cryotherapy) in eccentric phase, as well as a significant increase in vastus medialis activity (immediately after cryotherapy) in concentric phase were observed (P<0.05). Also, a significant decrease in median frequency of tibialis anterior (immediately after cryotherapy) was observed (P<0.05). No significant differences were observed among all 3 phases of movement in co-contraction of knee joint muscles (P>0.05). It seems that the immediate effects of cold spray on the muscles activity were not severe and long-term effects were very low. In addition, since co-contraction depends on the motor control of nervous system, probably cryotherapy effects used in this study was limited to the muscles and motor program of the central nervous system has not altered. Also, it is likely that as a result of decreasing conduction velocity in muscle tissue in the concentric phase, more motor units are recruited as a compensatory mechanism. Future studies are needed to identify other changes following cryotherapy.