The aim of this study is to investigate the effects of extracorporeal shock wave therapy (ESWT) on muscle rheological and functional properties in a population of young athletes. Thirty-two football and basketball players were recruited and randomized into two groups. The athletes underwent three sessions of therapy administered every five days to the thigh muscles. The treatment consisted of ESWT (electromagnetic generator, Energy Flux Density=0.03 mJ/mm2) or a placebo treatment bilaterally on the quadricep and femoral bicep muscles. Monitoring was carried out at recruitment (T0), at the end of treatment (15 days, T1) and at 30 days (T2) with myometric evaluation (measuring elasticity, stiffness and muscular tone) and electromiography exam (recording the Motor Unit Amplitude Potential values). The results showed a significant increase in the treated athletes in the elasticity (lateral vastus muscle, p=0.007), in muscular tone (femoral rectus, p=0.031) and in muscular recruitment (the lateral vastus, p<0.005; medial vastus muscle, p=0.055). These results could represent a translational interpretation of the known biological effect on connective tissue: an increase in blood flow, oxygenation, metabolic process activation and proliferative effect. The effects found may represent the justification for verifying the usefulness of using of shockwave therapy to reduce muscular fatigue and improve performance during the sport season.