تغییرات در گشتاور نیرو و نوسانات الکترومایوگرافی فلکسورهای عضله‌ی بازوی انسان پس از تمرین اکسنتریک حاد

نوع مقاله : مقاله های پژوهشی

نویسندگان

1 دانشیار، گروه فیزیولوژی ورزش، دانشکده‌ی تربیت بدنی و علوم ورزشی، دانشگاه اصفهان، اصفهان، ایران

2 استادیار، دانشکده‌ی مطالعات حرکت انسان، دانشگاه تکنولوژی کویینزلند، استرالی

چکیده

مقدمه: به طور کلی تمرین عضلانی حاد منجر به توسعه‌ی خستگی می‌شود که اثرات مخربی بر عملکرد دارد. هدف این مطالعه بررسی اثرات تمرین حاد اکسنتریک روی گشتاور نیرو و فعالیت الکتریکی فلکسورهای عضله‌ی بازوی انسان بود.روش‌ها: تعداد 16 مرد فعال سالم بدون هیچ گونه سابقه‌ی آسیب عضلانی بالاتنه، 10 ست 5 تکراری تمرین بیشینه‌ی اکسنتریک با یک دست غالب با استفاده از نیروسنج ایزوکنتیک بایودکس (سیستم، 3) در سرعت زاویه‌ای 120 درجه بر ثانیه در دامنه‌ی حرکتی 90 درجه‌ی مفصل آرنج را اجرا کردند. تغییرات در حداکثر گشتاور ارادی و فعالیت الکترومایوگرافی (ریشه‌ی مجذور میانگین، RMS) عضلات دو سر بازو و براکیالیس اندازه‌گیری شد.یافته‌ها: تمرین حاد اکسنتریک منجر به کاهش معنی‌داری در حداکثر گشتاور ارادی گردید (001/0 > P). هنگام تمرین اکسنتریک، متوسط کاهش حداکثر گشتاور ارادی (20/10) 21/28 درصد کاهش یافت (001/0 > P). در واقع، به طور متوسط مقادیر حداکثر گشتاور اکسنتریک از (28/11) 11/64 نیوتن بر متر در پنج تکرار عمل انقباضی اکسنتریک در ست اول به (66/10) 05/46 نیوتن بر متر در پنج تکرار عمل انقباضی اکسنتریک پایانی از ست دهم کاهش یافت. هم‌زمان با کاهش گشتاور نیرو، مقادیر نوسانات فعالیت الکترومایوگرافی (ریشه‌ی مجذور میانگین، RMS) عضلات دوسر بازو و براکیالیس نیز پس از جلسه‌ی تمرین اکسنتریک در سرعت زاویه‌ای مورد نظر پایین‌تر بود (001/0 > P). پس از جلسه‌ی تمرین حاد، متوسط مقادیر ریشه‌ی مجذور میانگین عضلات دوسر بازو و براکیالیس به ترتیب حدود 16/15 و 87/13 درصد کاهش یافت (001/0 > P).نتیجه‌گیری: نتایج نشان داد که یک جلسه تمرین حاد اکسنتریک منجر به کاهش معنی‌داری در حداکثر گشتاور ارادی و تغییرات الکترومایوگرافی فلکسورهای بازو هنگام اعمال عضلانی اکسنتریک گردید.

کلیدواژه‌ها


عنوان مقاله [English]

Changes in Torque and Electromyography of Human Elbow Flexors fol-lowing Acute Eccentric Exercise

نویسندگان [English]

  • Mehdi Kargarfard 1
  • Anthony Shield 2
1 Associate Professor, Department of Sport Physiology, School of Physical Education and Sport Sciences, Isfahan University, Isfahan, Iran
2 Assistant Professor, Department of Health, School of Human Movement Studies, Queensland University of Technology, Brisbane, Australia
چکیده [English]

Background: Acute muscular exercise generally induces the development of fatigue that has detrimental effects on performance. The purpose of this study was to examine the effects of acute eccentric exercise (ECC) training on torque and electromyography (EMG) activity of human elbow flexors.Methods: Sixteen healthy male active subjects with no previous history of pathology of the elbow performed ten sets of 5 repetitions of maximal eccentric muscle actions training (ECC-T) with one arm using the calibrated electronically Biodex isokinetic dynamometer (System 3: Biodex) at 120° s-1 velocity of the dominant elbow flexors determined at the elbow joint of 90° (1.57 rad). Changes in maximal voluntary torque and EMG activity (root mean square (RMS)) of biceps brachii and brachialis muscles were measured after acute ECC.Findings: The acute ECC induced a significant torque reduction (P < 0.01). During the exercise session, mean maximal voluntary eccentric torque reduction reached 28.21 ± 10.20% (P < 0.001). Indeed, average maximal eccentric torque values dropped from 64.11 ± 11.28 N/m for the first three muscle actions of the first set to 46.05 ± 10.66 N/m for the final five muscle actions of the tenth set. Concurrent to the torque decrease, the RMS values of the biceps brachii and brachialis muscles at the same velocity were significantly lower after the exercise session (P < 0.05). After the acute exercise session, mean RMS values of the biceps brachii and brachialis muscles reduction reached respectively 15.16% and 13.87% (P < 0.001). Conclusion: These results showed that an acute ECC induced a significant voluntary maximal torque and EMG reduction of human elbow flexors during eccentric muscle actions.

کلیدواژه‌ها [English]

  • Maximal voluntary torque
  • Myoelectrical activity
  • Biceps brachii
  • Eccentric training
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