A case study to analyse swimming techniques in front crawl, backstroke, breaststroke and butterfly stroke using a novice inertial measuring method with accelerometers and gyroscopes

conference paper

English

Top level swimming has seen a significant growth in performance over the past twenty years. The cause of this rise can be found not only in the great amount and intensity of swimming training, but also in science and research investigations in this sport. The aim of this paper is to present our new measurement method for inertial sensors and synchronous video recording used for the analysis of swimming techniques. Since 2009, we have been using two tachographs to measure swimming speed and to carry out its analysis. Results of tachograph measurements were published previously. In addition to tachographs, since the beginning of 2017, we have been using an inertial measurement unit to measure the acceleration of swimming. This unit contains sensors of inertial variables in the MicroElectroMechanical System (MEMS) technology. Specifically, it is a triaxial accelerometer and a triaxial gyroscope. Unit control and transmission of measured data are wireless via Wi-Fi interface. Motion of the swimmers being measured is graphically and numerically evaluated, along with synchronous recordings from three underwater camcorders. In the present article, we will focus only on measurements with the inertial measuring unit where we will introduce our new measuring method for the qualitative evaluation of front crawl, back stroke, breast stroke and butterfly technique of selected probands. For the measurement, probands swam their entire distance with an accelerometer mounted on a belt above their pelvic bone. When measuring with the accelerometer unit on 8 March, 26 April, 31 May, 18 September 2017, the national team of OLYMP Sport Centre of the Ministry of the Interior was measured, of which we selected for our case study: M.J. (year 1997) - front crawl. On the 100-metre track, in the first twenty-five metres, the proband reached the swimming efficiency of 98.4% with a coefficient of variation of 0.074% and swam at a mean speed of 2.29 m.s-2. The proband K.D. (1993) reached, on the 100-meter track, in the first twenty-five metres, the swimming efficiency of 98.7%, with the coefficient of variation of 6.74% and the mean speed of 1.93 m.s-2. The proband T. J. (1995) swam the 100-metre track of breast stroke and reached the swimming efficiency of 84% with the coefficient of variation of 25.63% and the mean swimming speed of 1.39 m.s-2. The proband J. B. (2000) swam the 50-metre track of butterfly stroke in the first twenty-five metres with the swimming efficiency of 90.22%, the coefficient of variation 18.88% and the mean speed of 1.51 m.s-2. The conducted research measurements have confirmed the ability of the new inertial unit with synchronous video recording to deliver reliable results from the speed and acceleration recording; this allows us to accurately and, in greater detail, analyse the respective swimming cycles. Thanks to these results, we can advise the coaches to correct the errors in the swimming technique and thereby to improve their swimming performance.

tachograph; speed; efficiency; frequency; freestyle; propulsion; drag

MOTYČKA, J.; BÁTOROVÁ, M.; PAŠEK, M.; ŠŤASTNÝ, J.; LEPKOVÁ, H.; KUMPÁN, P.

1. 12. 2017

MUNI Press

Brno

978-80-210-8917-4

Proceedings of the 11th International Conference on Kinanthropology

365

373

9

http://conference.fsps.muni.cz/media/3065171/proceedings-of-the-11th-conference-on-kinanthropology.pdf