Youth swimming performance may be influenced by anthropometric,

physiology, and biomechanical factors. The purpose of this study was to

analyze the relationships between 50-m front-crawl swimming performance and

relevant anthropometrical (body height, body mass, body mass index, arm

span, shoulders width, thigh, leg and upper arm lengths), muscle architectural

(muscle thickness, pennation angle, and fascicle length) and biomechanical

(stroke rate, stroke length, and stroke index) parameters in male young

swimmers, with 13.86±0.86 years of age (n = 23). Multiple regression analysis

was used to examine the variance of the 50 meters front-crawl. Results indicate

that stroke index, muscle thickness of Vastus Lateralis, and stroke length

explained %89 (p < .01) of 50-m front-crawl swimming performance variability in

these young male swimmers, and stroke index was the best single predictor of

swimming performance (R2=0.519, p<0.001). To conclude, performance of

young male swimmers in the 50 meters front-crawl is determined predominantly

by biomechanical and muscle architectural factors, and must be considered

when predicting success in young swimmers