Stroking characteristics of front crawl swimming

The aim of the study was to find explanations for the great variability of the technique performances of swimmers, observed during competition and practice. The study also aimed to find practical methods of data presentation in order to be able to follow the technique development of swimmers during the training process. Special interest was focused on investigating the effects of enhanced swimming intensity on the stroking strategy and the interrelationships between the stroke parameters during exercise. Mean velocity (v), stroke rate (SR), stroke length (SL), and stroke index (SI), as well as the duration of different phases of a stroke cycle, were considered as the parameters to describe the stroking characteristics of front crawl swimming. Blood lactate concentration (BLa) in relation to v was used to define the intensity categories during the tests. The subjects were 87 well-conditioned male competitive swimmers representing five different samples taken to participate in the studies. The results showed that the initial stroking strategy in training conditions was not very much different from that observed in competitions, reported in the scientific literature. Several factors, however, were noticed to effect the stroking strategy. The absolute values of v, SR, SL and SI changed with the enhancement in swimming intensity, and the five intensity categories were characterised by different relationships among the stroke parameters. The results also demonstrated that the physiological responses of the swimmers during exercise could be attributed to the variables of technique performance. The major findings showed that the changes in the SL could be connected with parallel changes in blood lactate oncentration, especially around the aerobic-anaerobic transition. Thus, it is suggested that the measurement of technique variables, under the influence of physiological stress and simultaneously with the physiological parameters, by examining the relationships between v, SR and SL in standardised pool testing conditions, should be a part of the control of training in swimmers.