The ultrasound measurements can quantify the potential for improving physical performance (e.g., sprint and repeated sprint performance, accelleration, reaction) by optimising body composition. The reliability and validity is not reached by any other method. This is an effective key for improving the performance of those athletes or players whose body fat is above the values expected in their sport. On the the other side, some athletes may have very or extremely low fat, which can be detrimental for performance and can lead to disastrous performance setbacks and severe diseases like anorexia nervosa.