Due to the increasingly sophisticated swimming technique, video analysis is no longer enough. In our research we used inertial sensors and high-speed video camera. Method enable us to analyze and improve the quality of swimming technique and training. The measurements were mostly performed on active swimmers, focusing on trajectory, speed, force, and power of the stroke. Sensors were placed on the palms and legs, which giving us insight into the asymmetry of the swimmer´s swim. The results of the analysis show that a more correct swimming technique has a great influence on the speed of the swimmer.