Accelerometer profile of motion of the pelvic girdle in butterfly swimming

Purpose: The aim of the study was to develop a method to measure and analyse kinematics of movement of the pelvic girdle in butterfly swimming in order to support training of technical skills. Methods: A device for recording triaxial accelerations and triaxial rotational angular velocities was mounted on the dorsal part of the pelvic girdle of athlete. The measurements were performed in ten elite butterfly swimmers (age: 23.1 ± 3.7 years, body height: 187.6 ± 4.3 cm, body mass 83.4 ± 6.33 kg). The task of the athlete was to swim one length of short course pool at maximal intensity. Individual mean graphical and numerical profiles of the kinematics of the movement of the pelvic girdle was computed, within the average cycle based on five consecutive cycles. Results: Statistical analysis of numerical individual parameters of profiles of the athletes studied revealed statistically significant differences between the swimmers. Statistically significant correlations were also found between personal best times in 50 m swimming (r = –0.76, p < 0.05) and 100 m swimming (r = –0.76, p < 0.05) and duration of the part of the cycle connected with the decline in velocity from maximum translational motion velocity obtained during propulsion with the upper and lower limbs to minimum value of the velocity obtained before the beginning of propulsion only with the lower limbs. Conclusion: The proposed measurement method, presentation and analysis of the profile of the pelvic girdle motion in butterfly swimming represents a good tool for fast and effective qualitative and quantitative biomechanical evaluation of movement technique components.