The present study analyzed the development of physiological, biomechanical and anthropometrical parameters in young female swimmers and assessed the effect of these parameters on swimming performance during biological maturation. In total, 26 female swimmers participated in the study in which data were annually collected for two consecutive years. Body composition, basic anthropometrical parameters and biological age were measured. During the 400 m front-crawl swimming, the energy cost of swimming and stroking parameters were assessed. Peak oxygen consumption (VO2 peak) was assessed by means of the backward-extrapolation technique recording VO2 during the first 20 sec of the recovery period after a maximal trial of 400 m distance. During the 2 year follow-up study period, age, height, body mass, body fat %, fat free mass, bone mineral mass, total bone mineral density, arm span and biological maturation values significantly increased during each year (p<0.05). The tracking of the physical characteristics measured over the 2-years study period was relatevely high (r > 0,694), except for the body fat% (r>0.554). The tracking of the Tanner stages was also high (r = 0.759-0.780). Stepwise regression analyses showed that biomechanical factors (R2 > 0.322;p<0.05) best characterized the 400 m swimming performance in young female swimmers, followed by bioenergetical (R2 > 0.311; p< 0.05) and physical (R2>0.203;p<0.05) factors during all three measurement times
