The aim of this study was to assess the relationship between the intra-cyclic variation of the horizontal velocity (dv) and the velocity of the 4 competitive swimming techniques in young swimmers. 45 young swimmers performed a set of maximal 4 × 25 m (freestyle, backstroke, breaststroke and butterfly stroke) swims with in water start. A speed-meter cable was attached to the swimmer's hip. The dv and the swimming velocity were analyzed. Within-subject tests presented significant variations in the dv based on the swimming technique. Post-hoc test revealed significant differences across all pair-wised swimming techniques (P<0.001), except for the comparison between freestyle and backstroke (P=0.98). The dv was higher in the breaststroke, followed by the butterfly, the backstroke and the freestyle. The quadratic models had the best goodness-of-fit and the lower error of estimation for the relationship between the dv and the swimming velocity in all swimming techniques (0.24 ≤ R(2) ≤ 0.51). As a conclusion, there is a non-linear relationship where the increase of swimming velocity leads to a decrease of dv in young competitive swimmers.

The aim of the study was to verify the relative contributions of energetic and kinematic parameters to the performance in 400-m front crawl test. Fourteen middle-distance swimmers participated in the study. Oxygen consumption was measured directly and blood samples were collected to assay lactate concentration. Both oxygen consumption and lactate concentration were used to calculate the: (i) overall energy expenditure, (ii) anaerobic (alactic and lactic) and (iii) aerobic contributions. The mean centre of mass speed and intracycle velocity variation were determined through three-dimensional kinematic analysis. Mean completion time was 315.64±26.91s. Energetic contributions were as follows: 6.1±0.28% from alactic anaerobic metabolism, 5.9±0.63% from anaerobic lactic and 87.8±0.88% from aerobic. Mean intracycle velocity variation was 0.14±0.03. The results indicated that performance of 400-m test relies predominantly on aerobic power. Parameters such as lactate, mean speed, anaerobic lactic and alactic (kW) correlated with performance of 400-m test (p <0.05). Multiple linear regressions indicated that mean centre of mass speed and anaerobic alactic (kW) determined the 400-m test performance (R2=0.92). Even though the T400 is characterized by aerobic metabolism, the anaerobic alactic component cannot be negligible at this competition level.

Background: In paralympic swimming, the biomechanical parameters related to performance are effectively determined according to the potentialities and peculiarities of each athlete. However, a clear integrated approach to these parameters for swimmers with physical disabilities at the speed of maximum oxygen uptake (vV̇O2max) is still practically non-existent. Objective: The purpose of this study was twofold: (i) to assess kinematic, coordinative and efficiency parameters measured at vV̇O2max in swimmers with physical impairments; and (ii) to correlate these biomechanical parameters with the time for a 200 m maximum test. Methods: Eleven swimmers with physical disabilities (seven males and four females) were assessed at vV̇O2max with support from a three-dimensional kinematic method. The performance parameters analysed were: (i) kinematic - stroke rate (SR), stroke length (SL), average swimming speed (SS) and intra-cyclic velocity variation (IVV); (ii) coordinative - index of coordination (IdC) and adapted index of coordination (IdCadapt); and (iii) swimming efficiency - propelling efficiency (çp). Results: The overall results showed high dispersion and wide confidence intervals for the kinematic and coordinative variables. The mean and standard deviation of vV̇O2max and V̇O2 at the same intensity were 0.90 ± 0.13 m/s and 38.2 ± 8.3 ml/kg/min, respectively. Conclusion: Swimmers with less significant impact of physical disability on specific swimming tasks presented higher SL, SS and çp. The IVV was higher in swimmers with a greater impact of disability on conducting specific competitive swimming tasks. In general, the catch-up inter-arm coordination model is adopted.

Biomechanical and coordination measurements are useful tools to assess swimming performance. Regarding Paralympic swimming, function and technique make these measurements complex. The aim of this study was to perform a systematic review of studies on biomechanics, coordination and performance in disabled swimmers following swimming protocols and in competitions. Data sources: PubMed, EMBASE, ISI Web of Knowledge, SPORTDiscus and Academic Search Premier. We selected complete studies, published until June 2018. Eighteen studies satisfied the inclusion criteria and were selected for qualitative analysis; nine of these were included in the meta-analysis. Swimming speed and stroke length increase with less impact of physical, visual and intellectual impairment on performing specific swimming tasks. Stroke rate is more stable all through the sport classes than both swimming speed and stroke length. Most physically disabled swimmers adopt the catch-up coordination model. Stroke rate is responsible for most of the intracycle velocity variation in swimmers with amputations or malformations of the upper limbs. No study was found on propulsive efficiency. Swimmers with disabilities should work more on stroke rate, with small decreases in stroke length to achieve higher swimming speeds, lower swim coordination index (more negative) and lower speed variations.