Study aim: To assess the effects of swimming training on anaerobic endurance, swimming velocity and chest girth in children aged 12 years.Material and methods: Two groups of children aged 12 years were studied. Group S (14 boys and 6 girls) training swimming at a sport-oriented school 3 days a week, 90 min per session, and Group R (6 boys and 6 girls) engaged in competitive swimming for 4 years. Children from Group S were subjected twice (in September and in February) to a swimming test consisting of 6 bouts of swimming the 12.5-m distance, spaced by 30-s intermissions. Mean and maximum swimming velocities in the entire test were recorded together with their ratio (Performance Index, PI). In children from Group R the swimming velocity at one 12.5-distance was recorded.Results: Apart from somatic indices, significant increases over the 5-month training period were noted in mean swimming velocity in boys and girls (p<0.001) and in maximum velocity in boys (p<0.01). No significant changes were noted in the performance index or in heart rate.Conclusions: Performance index as a measure of anaerobic endurance may serve as a useful tool in assessing the adaptive performance changes in young swimmers.
Study aim: To assess the effects of 8-week endurance training in swimming on work capacity of boys aged 12 years.Material and methods: The following groups of schoolboys aged 12 years were studied: untrained control (UC; n = 14) and those training swimming for two years. The latter ones were subjected to 8-week training in classical style (CS; n = 10) or free style (FS; n = 13). In all boys maximal oxygen uptake (O2max) was determined, and the CS and FS groups were subjected to 6 tests: swimming at 50 and 400 m distances (time recorded) and to 12-min swimming (distance recorded), all by free and classical styles pre- and post-training. From swimming times at 50 and 400 m distances the so-called critical swimming speed (CSS) was computed: CSS = (400 - 50) / (t400 - t50).Results: No training-induced improvement in O2max was noted in any group. Yet, boys subjected to classical style training significantly (p<0.05) improved their free-style swimming velocity at CSS and at the 400-m distance by about 6%, and their heart rate following the 12-min test in classical style decreased by nearly 16% (p<0.001) compared with the pre-training values.Conclusions: The 8-week training in given swimming style does not negatively affect the performance in other style than the trained one. This may be of importance in competitive training.
The kinematic profiles of the hip and center of mass in front crawl swimming were compared to quantify the error of using a fixed body point to assess intracyclic velocity variations at moderate intensity exercise. The practical goal was to provide a useful tool, easy and fast to assess, and to use as feedback, for assessing swimming efficiency. Sixteen swimmers performed an intermittent incremental protocol that allowed assessing the individual anaerobic threshold velocity. One complete stroke cycle was analysed at the step intensity corresponding to each swimmer's anaerobic threshold. The subjects were videotaped in the sagittal plane using a double camera set-up for two-dimensional kinematical analyses. The hip and the center of mass presented similar mean velocity and displacement values, being highly related to both parameters. However, the hip reflects the center of mass forward velocity and horizontal displacement with 7.54% and 3.24% associated error, respectively. Differences between hip and center of mass were observed for intracyclic velocity variations (0.19±0.05 and 0.25±0.08, respectively, for a p<0.001), and the negative mean error value found (-0.06) evidenced a tendency of the hip to overestimate the center of mass velocity variation. It is possible to conclude that the hips forward movements might provide a good estimate of the swimmer's horizontal velocity and displacement that is relevant for diagnostic purposes, especially to assess swimming efficiency through the intracyclic velocity variations. Nevertheless, the hip point error magnitude should be taken into consideration in data interpretation.
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