Training volume in swimming is usually very high when compared to the relatively short competition time. High-intensity interval training (HIIT) has been demonstrated to improve performance in a relatively short training period. The main purpose of the present study was to examine the effects of a 5-week HIIT versus high-volume training (HVT) in 9–11-year-old swimmers on competition performance, 100 and 2,000 m time (T100 m and T2,000 m), VO2peak and rate of maximal lactate accumulation (Lacmax). In a 5-week crossover study, 26 competitive swimmers with a mean (SD) age of 11.5 ± 1.4 years performed a training period of HIIT and HVT. Competition (P < 0.01; effect size = 0.48) and T2,000 m (P = 0.04; effect size = 0.21) performance increased following HIIT. No changes were found in T100 m (P = 0.20). Lacmax increased following HIIT (P < 0.01; effect size = 0.43) and decreased after HVT (P < 0.01; effect size = 0.51). VO2peak increased following both interventions (P < 0.05; effect sizes = 0.46–0.57). The increases in competition performance, T2,000 m, Lacmax and VO2peak following HIIT were achieved in significantly less training time (~2 h/week).

The aims of this study were to compare drag in swimming children and adults, quantify technique using the technique drag index (TDI), and use the Froude number (Fr) to study whether children or adults reach hull speed at maximal velocity (v max ). Active and passive drag was measured by the perturbation method and a velocity decay method, respectively, including 9 children aged 11.7 ± 0.8 and 13 adults aged 21.4 ± 3.7. The children had significantly lower active (k AD ) and passive drag factor (k PD ) compared with the adults. TDI (k AD /k PD ) could not detect any differences in swimming technique between the two groups, owing to the adults swimming maximally at a higher Fr, increasing the wave drag component, and masking the effect of better technique. The children were found not to reach hull speed at v max , and their Fr were 0.37 ± 0.01 vs. the adults 0.42 ± 0.01, indicating adults' larger wave-making component of resistance at v max compared with children. Fr is proposed as an evaluation tool for competitive swimmers.

The main aim of this study was to investigate the effect of finger spread on the propulsive force production in swimming using computational fluid dynamics. Computer tomography scans of an Olympic swimmer hand were conducted. This procedure involved three models of the hand with differing finger spreads: fingers closed together (no spread), fingers with a small (0.32 cm) spread, and fingers with large (0.64 cm) spread. Steady-state computational fluid dynamics analyses were performed using the Fluent code. The measured forces on the hand models were decomposed into drag and lift coefficients. For hand models, angles of attack of 0°, 15°, 30°, 45°, 60°, 75°, and 90°, with a sweep back angle of 0°, were used for the calculations. The results showed that the model with a small spread between fingers presented higher values of drag coefficient than did the models with fingers closed and fingers with a large spread. One can note that the drag coefficient presented the highest values for an attack angle of 90° in the three hand models. The lift coefficient resembled a sinusoidal curve across the attack angle. The values for the lift coefficient presented few differences among the three models, for a given attack angle. These results suggested that fingers slightly spread could allow the hand to create more propulsive force during swimming.

Little is known about the relationship between real and perceived water competence among youth in the context of drowning prevention or of their perceptions of their risk of drowning. This study reports the findings of an international project entitled Can You Swim? Collegiate physical education students (n = 373) were assessed in a two-part study using an initial questionnaire survey to provide self-estimates of water competency and risk perception, followed by six practical tests in the water. Correlation coefficients between perceived and real swimming (r s = 0.369) and floating (r s = 0.583) skills were significant but only moderate in strength. No significant gender differences in real or perceived water competency were found. Significantly more males than females estimated lower risk of drowning associated with a series of aquatic scenarios (p = 0.016). The implications of these findings on drowning prevention and the need for further investigation are discussed.While the role of swimming proficiency in drowning prevention may appear axiomatic, its protective capacity is not well understood. Brenner, Saluja, and Smith (2003) have argued that increased swimming competency is almost certain to be protective in a drowning situation and, if so, then differences in swimming competency may help explain why some are at greater risk of drowning than others. The relationship between swimming competency, swimming lessons, and the risk of drowning for young children has been the subject of some inquiry (Brenner, Moran, Stallman, Gilchrist, & McVan, 2006), but little is known about this relationship with respect to young adults, one of the most at-risk groups of drowning in most developed countries.A systematic, large-scale review of childhood and youth drowning noted that even though studies have shown that swimming lessons improved the ability to dive,

This file was dowloaded from the institutional repository Brage NIH -brage.bibsys.no/nih Vaz, J. R., Olstad, B. H., Cabri, J. M. H., Kjendlie, P.-L., Pezarat Correia, P., Hug, F. (2016). Muscle coordination during breaststroke swimming:Comparison between elite swimmers and beginners. Journal of Sports Sciences, 34, 1941Sciences, 34, -1948 AbstractThe present study aimed to compare muscle coordination strategies of the upper and lower limb muscles between beginners and elite breaststroke swimmers. Surface electromyography of eight muscles was recorded in 16 swimmers (eight elite, eight beginners) during a 25m swimming breaststroke at 100 % of maximal effort. A decomposition algorithm was used to identify the muscle synergies that represent the temporal and spatial organization of muscle coordination. Between-groups indices of similarity and lag times were calculated. Individual EMG patterns were moderately to highly similar between groups (between-group indices range: 0.61 to 0.84). Significant differences were found in terms of lag time for pectoralis major (p < 0.05), biceps brachii, rectus femoris and tibialis anterior (p < 0.01), indicating an earlier activation for these muscles in beginners compared to elites (range: -13.2 to -3.8 % of the swimming cycle). Three muscle synergies were identified for both beginners and elites. Although their composition was similar between populations, the third synergy exhibited a high within-group variability. Moderate to high indices of similarity were found for the shape of synergy activation coefficients (range: 0.63 to 0.88) but there was a significant backward shift (-8.4 % of the swimming cycle) in synergy #2 for beginners compared to elites. This time shift suggested differences in the global armto-leg coordination. These results indicate that the synergistic organization of muscle coordination during breaststroke swimming is not profoundly affected by expertise. However, specific timing adjustments were observed between lower and upper limbs.