The effects of creatine long-term supplementation on muscle morphology and swimming performance in rats

creatine (cr) has been shown to increase the total muscle mass.the purpose of this study was to investigate the effect of crsupplementation on muscle morphology and swimmingperformance, using an animal model. each rat was subjected toexercise 15-minute period daily for the 12 weeks. the rats wererandomly divided into four groups: no cr supplementation(con), no cr supplementation and incomplete food intake(lacking lysine and methionine in diet for rats) (inco), crsupplementation 1 g·kg-1·day-1 (creat-i) and cr supplementation2 g·kg-1·day-1 (creat-ii). three months later, all groupsadult rats exercised in swimming pool chambers. swimmingtime was recorded as minute for each rat. following swimmingperformance period, the animals were killed by cervicaldislocation and the gastrocnemius and diaphragm muscles weredissected. serial slices of 5-7 mu were allocated paraffin waxand histochemical staining procedure of cross-sections wascarried out with heamatoxylin-eosin technics. all groups gainedbody weight at the end of 12 weeks but there was no statisticaldifference among them. swimming time values were statisticaldifference between creat-ii and con group as well asbetween creat-i and con group (p < 0.05). in the incogroup was determined increased connective tissue cell of themuscle sample. in contrast, in the creat-i and creat-iigroup, the basic histological changes were large-scale musclefibers and hypertrophic muscle cells. these results suggest thatlong-term creatine supplementation increased the number ofmuscle fibers and enhanced endurance swimming performancein rats.