INTRODUCTION: The aim of this study is to identify errors in leg and monofin movement structure, lowering the effectiveness of swimming. With this information on errors, the crucial sequences in monofin swimming were identified. METHODS: Six high level monofin swimmers conducted a progressive trial (900m at increasing speeds). One cycle of each swimmer was filmed and analyzed (SIMI). Results were obtained in the form of time dependent series for: angle of foot bending in relation to the shank and proximal part of the fin in relation to the foot and for angle of attack: the distal part and entire fin surface. The choice of parameters was based on a devised monofin swimming model (Rejman, 2009). The errors were quantified by calculating the difference of the fields estimated by registered and model series. The range of errors were illustrated by the movement sequence registered, which were compared with sequences that accomplished the model or were slightly different. RESULTS: Based on information related to the scale and structure of errors committed by swimmers the following suggestions were formulated: the errors in angular displacement studied mostly exceeded the pattern of model, with the exception of the dorsal flexion of feet in the upbeat, performed by the slowest swimmer; the most difficult element of monofin swimming is the proper range of motion in the ankle joints; the parameter most differentiating the swimmers, is the angle of bend of the feet: the errors estimated were high correlated to swimming velocity. The information related to errors creates a basis for isolating crucial sequences of leg movements and monofin, which allows the description of key elements in the swimming technique. DISCUSSION: Controlling foot movement allows use of the torque of transfer to initiate propulsion through the bending of the tail and changing of the structure of waterflow over the of the fin. Correct crucial sequences allow for use of the monofin to achieve maximum swimming speed. That is why the identification and of key elements in the movement structure, and the quantification of their quality, is justified within the aim of anticipating and eliminating errors.
© Copyright 2010 Biomechanics and Medicine in Swimming XI. Published by Norwegian School of Sport Sciences. All rights reserved.