Effect of eccentric exercise of structural changes in human skeleta muscle

Telesna vadba s prevladujočim deležem ekscentričnih mišičnih kontrakcij (ekscentrična vadba) naj bi spodbudila večji prirast mišične mase in jakosti kot običajna vadba proti uporu. Mehanizmi delovanja ekscentrične vadbe še niso v celoti pojasnjenipredvideva se, da imajo pomembno vlogo mikropoškodbe, ki izzovejo naknadno ojačitev tkiva. Namen članka je pregledati objavljene dokaze o vplivu ekscentrične vadbe na spremembo strukture skeletnih mišic pri ljudeh. Metode: Literaturo smo iskali v podatkovnih zbirkah PubMed in Cochrane Library z uporabo kombinacije ključnih besed v angleškem jeziku. Vključili smo raziskave, ki so proučevale zdrave odrasle ljudi. Rezultati: V pregled literature je bilo vključenih devet poročil o raziskavah, ki so proučevale strukturne spremembe po enkratni vadbeni enoti ali po nekajtedenski ekscentrični vadbi. Ugotovljene so bile pomembne spremembe prečnega preseka in debeline mišice, dolžine in kota fasciklov, prostornine in vsebnosti vode v mišici, anabolizma mišičnih proteinov ter strukture T-tubulov. Zaključki: Enkratna ekscentrična preobremenitev mišice povzroči mikro poškodbe celic, dlje časa trajajoča ekscentrična vadba pa povzroči trajne izboljšave mišične strukture in hipertrofijo skeletne mišice. Za oblikovanje trdnih zaključkov je potrebno več metodološko primerljivih raziskav, narejenih na večjih vzorcih.Exercise training comprised of predominantly eccentric muscle contractions (eccentric exercise) is supposed to elicit higher gains in muscle mass and strength than standard resistance training. Mechanisms of eccentric exercise are not yet fully understoodit is assumed that microtrauma plays a key role in triggering subsequent reinforcement of tissue. The purpose is to review published evidence on the influence of eccentric exercise on skeletal muscle structure in humans. Methods: We searched for research reports published in English language in PubMed and Cochrane Library databases. The review was limited to studies performed on healthy adult human subjects. Results: Nine articles reporting structural changes of skeletal muscles after either a single bout of eccentric exercise or prolonged training programme were included in the review. Significant changes in muscle cross-section area, thickness, fascicle length and angle, oedema, anabolism of muscle proteins and changes in T-system structure were reported. Conclusions: A single bout of eccentric muscle overload causes microtrauma to the cells, whereas prolonged eccentric training leads to lasting improvements in skeletal muscle structure and hypertrophy. More methodologically comparable studies conducted on larger samples are needed to draw definite conclusions in this regard