Measurement of adolescent swimmers over a 50m swim distance at maximum crawl speed using a triaxial accelerometer and thrust measurement

The aim of this study was to analyze the technique and kinematic changes occurring under fatigue in athletes. For each athlete, the individual characteristics of the kinematics of the hip girdle movement during the averaged cycle for the first and second lap were calculated. A special inertial device with a built-in triaxial gyroscope and triaxial accelerometer was used to measure and record changes in velocity and acceleration (REJ62g, JD Jarosław Doliński, Poland). The device (65x50x30 mm, 95 g) was placed in the foam in such a way as to minimize hydrodynamic drag while ensuring stable restraint on the dorsal aspect of the swimmer’s iliac rim.Samples:The study included 24 girls (age 12.57 ± 0.55 years; body height 164.1 ± 8.3 cm; body mass 51.3 ± 8.4 kg; body fat 20.2% ± 2.9%; 50 m crawl swim time 32.15 ± 2 s) and 14 boys (age 12.51 ± 0.6 years; body height 166 ± 8.3 cm; body mass 49.1 ± 9.4 kg; body fat 13.6% ± 2.0%; 50 m crawl swim time 30.4 ± 2.8 s). All of the subjects were participants in a Youth National Team training camp in the Mazovia Province, to which athletes are appointed who rank in the top ten in their age category at Olympic distances in Poland based on www.swimrankings.net.Procedures   Measurements were taken in a 25-meter pool while swimming at maximum velocity. The athletes did not jump from the starting blocks but instead began by pushing off from the wall, swimming two laps between which they made a flip turn typical of crawl.The dataset contains columns:A - G - the anonymized data of the subjects studied. H - M - results of a 10-second measurement of thrust strength.N - FC - processed test data obtained with a three-axis accelerometer. Legend:L – motion during active left upper limb,R – motion during active right upper limb,I25 – the first part (25 m) of the analyzed effort,II25 – the second part (25 m) of the analyzed effort,Av [m/s2] – acceleration along the vertical axis in traversing movements.Ab [m/s2] - acceleration along the transverse axis.Gs_MAX [deg/s] – angular velocity around the sagittal axis of the athletes in yaw movements (yaw rotation),Czas do MAX [s] – time needed to achieve.Gv [deg/s] – angle around the long axis in rotation movements,KGodn [deg] – maximum angle around the long axis in rotation movements