UDC: 796.015.363

doi:10.5633/amm.2013.0413

 

 

FACTORS OF SUCCESS IN ENDURANCE SPORTS; CHANGING OF MUSCLE FIBER TYPE

 

Luka Smrkolj, Branko Škof

 

 

University in Ljubljana, Faculty of Sports, Ljubljana, Slovenia

Endurance is one of the factors which considerably influences performance of sportsmen. One important factor is a change in muscle fiber type. The latter is determined by the speed of contraction and histochemical analysis of the muscle fiber. The typology of muscle fibers is divided into three aspects: histochemical aspect (I, IIa and IIb), mechanical aspect (slow oxidative - SO, fatigue resistant - FR, and fatigable fibers - FF) and biological aspect (slow aerobic, fast aerobic, fast glycolytic). A human is born, on average, with a higher ratio (50-55%) of slow muscle fibers. During development, the share varies by type of activity that might occur. It is assumed that athletes who perform short abrupt action need more of the fast glycolytic IIb fibers than other athletes. On the other hand, endurance sports require a higher ratio of slow oxidative type I muscle fiber from athletes. Characteristics of specific adjustments depending on the type of exercise have been recognized. Prolonged endurance exercise elicits different metabolic and morphological changes including mitochondrial biogenesis, transforming fast into slow muscle fibers and metabolism substrate. In contrast, heavy exercise stimulates the synthesis of proteins responsible for contractive muscle hypertrophy and increases maximum contraction. Acta Medica Medianae 2013;52(4):69-74.

 

      Key words: endurance training, resistance training, changing musc le type