Introduction: Eccentric exercise is a popular form of exercise within both training and rehabilitation programs. During eccentric contraction, tension develops in a muscle, so the muscle generates force while its length increases. Eccentric training typically induces delayed onset muscle soreness, but the background mechanism has not been yet clearly explained. Within possible mechanisms there are also structural changes in muscle after eccentric training. Purpose: The purpose of the following diploma work is to determine the impact of eccentric exercise on structural changes of skeletal muscles in humans, based on a review of the literature. Methods: Descriptive method with a literature review was used. The literature in English or German was being searched in the PubMed, Cochrane Library and Medline databases. We used the combination of the following key words: »muscle OR muscle fibre OR muscle bundle OR sarcomere« AND »architectural changes OR mechanical changes OR structure changes OR morphologic changes« AND »eccentric exercise OR eccentric training OR eccentric contraction«. Among inclusion’s criteria there was no time frame of publishing date, but all studies had to include healthy adult participants. Results: Based on inclusion and exclusion criteria, at the end there were nine articles included to literature review. All of them reported structural changes of muscles after single or repeated bouts of eccentric exercise. Magnetic resonance imaging, ultrasonography and needle muscle biopsy were used in the studies to determine structural changes. There were changes in muscle cross section area, muscle thickness, fascicle length and angle, volume and swelling, water, desmin, dystrophin and STARS content as well as changes in T-system reported. Discussion and conclusion: Eccentric exercise induces muscles structural changes after both single and repeated bouts of exercise. Changes occur at the level of whole muscle as well as on the cellular level. Studies about structural changes after eccentric exercise are difficult to compare due to many different methodological approaches. More randomized controlled studies with comparable methodological approaches are needed to be able to form solid conclusions.
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