Is There Any Effect of Symmetry on Velocity of the Four Swimming Strokes?

The different characteristics of the four swimming strokes affect the interplay between the four limbs, acting as a constraint to the force produced by each hand and foot. The purpose of this study was to analyze the symmetry of force production with a varying number of limbs in action and see its effect on velocity. Fifteen male swimmers performed four all-out bouts of 25-m swims in the four strokes in full-body stroke and segmental actions. A differential pressure system was used to measure the hands/feet propulsive force and a mechanical velocity meter was used to measure swimming velocity. Symmetry index was calculated based on the force values. All strokes and conditions presented contralateral limb asymmetries (ranging from 6.73% to 28% for the peak force and from 9.3% to 35.7% for the mean force). Backstroke was the most asymmetric stroke, followed-up by butterfly, front crawl, and breaststroke. Kicking conditions elicited the higher asymmetries compared with arm-pull conditions. No significant associations were found between asymmetries and velocity. The absence of such association suggests that, to a certain and unknown extent, swimming may benefit from contralateral limb asymmetry.

Are Young Swimmers Short and Middle Distances Energy Cost Sex-Specific?

This study assessed the energy cost in swimming (C) during short and middle distances to analyze the sex-specific responses of C during supramaximal velocity and whether body composition account to the expected differences. Twenty-six swimmers (13 men and 13 women: 16.7 ± 1.9 vs. 15.5 ± 2.8 years old and 70.8 ± 10.6 vs. 55.9 ± 7.0 kg of weight) performed maximal front crawl swimming trials in 50, 100, and 200 m. The oxygen uptake (V˙O2) was analyzed along with the tests (and post-exercise) through a portable gas analyser connected to a respiratory snorkel. Blood samples were collected before and after exercise (at the 1st, 3rd, 5th, and 7th min) to determine blood lactate concentration [La–]. The lean mass of the trunk (LMTrunk), upper limb (LMUL), and lower limb (LMLL) was assessed using dual X-ray energy absorptiometry. Anaerobic energy demand was calculated from the phosphagen and glycolytic components, with the first corresponding to the fast component of the V˙O2 bi-exponential recovery phase and the second from the 2.72 ml × kg–1 equivalent for each 1.0 mmol × L–1 [La–] variation above the baseline value. The aerobic demand was obtained from the integral value of the V˙O2 vs. swimming time curve. The C was estimated by the rate between total energy releasing (in Joules) and swimming velocity. The sex effect on C for each swimming trial was verified by the two-way ANOVA (Bonferroni post hoc test) and the relationships between LMTrunk, LMUL, and LMLL to C were tested by Pearson coefficient. The C was higher for men than women in 50 (1.8 ± 0.3 vs. 1.3 ± 0.3 kJ × m–1), 100 (1.4 ± 0.1 vs. 1.0 ± 0.2 kJ × m–1), and 200 m (1.0 ± 0.2 vs. 0.8 ± 0.1 kJ × m–1) with p < 0.01 for all comparisons. In addition, C differed between distances for each sex (p < 0.01). The regional LMTrunk (26.5 ± 3.6 vs. 20.1 ± 2.6 kg), LMUL (6.8 ± 1.0 vs. 4.3 ± 0.8 kg), and LMLL (20.4 ± 2.6 vs. 13.6 ± 2.5 kg) for men vs. women were significantly correlated to C in 50 (R2adj = 0.73), 100 (R2adj = 0.61), and 200 m (R2adj = 0.60, p < 0.01). Therefore, the increase in C with distance is higher for men than women and is determined by the lean mass in trunk and upper and lower limbs independent of the differences in body composition between sexes.

Swimming Phase-Based Performance Evaluation Using a Single IMU in Main Swimming Techniques

Comprehensive monitoring of performance is essential for swimmers and swimming coaches to optimize the training. Regardless of the swimming technique, the swimmer passes various swimming phases from wall to wall, including a dive into the water or wall push-off, then glide and strokes preparation and finally, swimming up to the turn. The coach focuses on improving the performance of the swimmer in each of these phases. The purpose of this study was to assess the potential of using a sacrum-worn inertial measurement unit (IMU) for performance evaluation in each swimming phase (wall push-off, glide, stroke preparation and swimming) of elite swimmers in four main swimming techniques (i.e. front crawl, breaststroke, butterfly and backstroke). Nineteen swimmers were asked to wear a sacrum IMU and swim four one-way 25 m trials in each technique, attached to a tethered speedometer and filmed by cameras in the whole lap as reference systems. Based on the literature, several goal metrics were extracted from the instantaneous velocity (e.g. average velocity per stroke cycle) and displacement (e.g. time to reach 15 m from the wall) data from a tethered speedometer for the swimming phases, each one representing the goodness of swimmer’s performance. Following a novel approach, that starts from swimming bout detection and continues until detecting the swimming phases, the IMU kinematic variables in each swimming phase were extracted. The highly associated variables with the corresponding goal metrics were detected by LASSO (least absolute shrinkage and selection operator) variable selection and used for estimating the goal metrics with a linear regression model. The selected kinematic variables were relevant to the motion characteristics of each phase (e.g. selection of propulsion-related variables in wall push-off phase), providing more interpretability to the model. The estimation reached a determination coefficient (R2) value more than 0.75 and a relative RMSE less than 10% for most goal metrics in all swimming techniques. The results show that a single sacrum IMU can provide a wide range of performance-related swimming kinematic variables, useful for performance evaluation in four main swimming techniques.

Effect of Additional Buoyancy Swimsuits on Performance of Competitive Swimmers

Background: When in water, the Centers of Buoyancy (CoB) and Mass (CoM) of the human body are positioned cranially and caudally, respectively. With increasing distance between these centers, the sinking torque of the lower limbs increases, with a subsequent decrease in swimming performance due to increased drag. Objective: To clarify the effect of additional buoyancy swimsuits on swimming performance. Methods: The subjects were eight competitive male swimmers of mean ±SD age 21±2 years. Swimming performance was compared between Conventional (CS) and Additional Buoyancy Swimsuits (ABS). CoM and CoB were identified on land and in water, respectively, with the swimmers maintaining a horizontal posture. CoM was measured by the reaction board method. CoB was calculated as the force exerted in the vertical direction accompanied by changes in inspiratory volume. Swimming velocity and Blood Lactate (BL) concentration value during 200 m front crawl in trials at four different speeds (curve test) were recorded as swimming performance. Results: No significant difference in inspiratory volume was observed between CS and ABS (small effect size, d=0.28). The distance between CoM and CoB was significantly shorter for CS than ABS (p < 0.001; large effect size, d=1.08). Both swimming velocity at BL of 4 mmol·L-1 and maximal effort were significantly faster for ABS (p < 0.042; 0.008), with large effect size (d=0.91; 0.98). However, there was no significant difference in maximal BL between CS and ABS (small effect size, d=0.37). Conclusion: ABS improves swimming performance by streamlining the horizontal posture.

The effect of hand posture on swimming efficiency

Our quest is for the thumb and finger positions that maximize drag in front crawl swimming and thus maximize propulsion efficiency. We focus on drag in a stationary flow. Swimming is in water, but using Reynolds similarity the drag experiments are done in a wind tunnel. We measure the forces on real-life models of a forearm with hands, flexing the thumb and fingers in various positions. We study the influence on drag of cupping the hand and flexing the thumb. We find that cupping the hand is detrimental for drag. Swimming is most efficient with a flat hand. Flexing the thumb has a small effect on the drag, such that the drag is largest for the opened (abducted) thumb. Flow structures around the hand are visualized using robotic volumetric particle image velocimetry. From the time-averaged velocity fields we reconstruct the pressure distribution on the hand. These pressures are compared to the result of a direct measurement. The reached accuracy of $$\approx$$ ≈ 10% does not yet suffice to reproduce the small drag differences between the hand postures. Graphical Abstract

What Is the Optimal Strength Training Load to Improve Swimming Performance? A Randomized Trial of Male Competitive Swimmers

This study aimed to compare the effectiveness of high, moderate, and low resistance training volume-load of maximum strength training on muscle strength and swimming performance in competitive swimmers. Thirty-three male swimmers were randomly allocated to high (age = 16.5 ± 0.30 years), moderate (age = 16.1 ± 0.32 years) and a low resistance training volume-load group (age = 15.9 ± 0.31). This study was carried out in mid-season (January to March). Pre and post strength (e.g., repetition maximum [1RM] leg extension and bench press tests), swimming (25, 50 m front-crawl), start (speed, time, distance) and turn (time of turn) performance tests were conducted. Our findings revealed a large main effect of time for 1RM bench press: d = 1.38; 1RM leg extension: d = 1.55, and for 25 (d = 1.12), and 50 m (d = 1.97) front-crawl, similarly for start and turn performance (d = 1.28–1.46). However, no significant Group × Time interactions were shown in all strength swimming performances, start and turn tests (p > 0.05). In conclusion, low training loads have been shown to elicit the same results as moderate, and high training loads protocol. Therefore, this study shows evidence that the addition of low training volume-loads as a regular part of a maximal strength training regime will elicit improvements in strength and swimming performance.

Relationship between Swimming Performance, Biomechanical Variables and the Calculated Predicted 1-RM Push-up in Competitive Swimmers

One repetition maximum (1RM) push-ups, based upon the load–velocity relationship, are able to predict the maximum upper body strength. The aim of the present study was to examine the relationship between the predicted 1RM push-up based upon the load–velocity relationship and swimming performance and kinematical variables in competitive swimmers. Thirty-three competitive male swimmers (age = 16.46 ± 0.59 years, body mass = 72.82 ± 8.41 kg, body height = 180.56 ± 5.69 cm) performed push-up exercises without a weight vest and with a 10, 20 and 30 kg weight vests. A load–velocity relationship was established as a product of the load and velocity of the push-up per participant, and the equation was used to establish a predicted 1RM. Our findings showed a predicted 1RM push-up of 82.98 ± 9.95 kg. Pearson correlations revealed a nearly perfect relationship between the 1RM push-up and the 25 or 50 m front crawl (r = −0.968, r = −0.955), and between 1RM push-up and the 25 or 50 m front crawl with arms (r = −0.955, r = x0.941). Similarly, our results revealed significant near-perfect correlations between 1RM push-up and kinematical variables (r = 0.93–0.96) except the stroke index, which had a large relationship (r = 0.56). This study suggests that swimming performance and kinematical variables are correlated with the predicted 1RM push-up. The 1RM push-up based upon the load–velocity relationship is a low cost and time-effective alternative for swimmers and coaches to predict maximum upper body strength to optimize swimming performance in short races.

Effect of training using the technology of teaching basic competitive swimming techniques to children with cerebral palsy

Purpose: According to many scholars, sport is essential for social adaptation and integration of people with disabilities. Therefore, it is important to research innovative technologies for teaching competitive swimming technique to 8-10-year- old children with cerebral palsy. The aim of this study is to develop the technology of teaching competitive swimming techniques to children with cerebral palsy and to evaluate its effectiveness for mastering the front crawl swimming technique. Materials and methods: analysis of scientific literature, questionnaires (e-correspondence), pedagogical experiment, expert survey, determination of the coefficient of technique efficiency, statistical methods. A total of 15 qualified swimming coaches participated in this study. The experiment involved 29 children who were diagnosed with cerebral palsy. Results: the main means of technology implementation is the web-based information system SwimCP (Swimming with Cerebral Palsy), which promotes effective swimming teaching for children with cerebral palsy at the initial stage of sports training by selecting and recommending an approximate complex of exercises that take into account the peculiarities of motor disturbance in accordance with the specific form of cerebral palsy and the stage of motor activity training. Conclusion: using expert assessment and the coefficient of swimming technique efficiency determination, it is confirmed that the proposed technology of teaching basic competitive swimming techniques to children with cerebral palsy is effective. Resumen: Objetivo: Según muchos estudiosos destacados, el deporte es fundamental para la adaptación social y la integración de las personas con discapacidad. Por lo tanto, es importante investigar modelos innovadores para enseñar brazadas de natación competitiva a niños con parálisis cerebral. El objetivo del estudio es diseñar el modelo pedagógico de enseñanza de los estilos básicos de natación competitiva a niños con parálisis cerebral y evaluar su efectividad para dominar el estilo de natación estilo crol. Material y métodos: Se utilizó una metodología de investigación selectiva. Implicó la recopilación directa de datos gracias a la encuesta a los participantes. Los resultados mostraron que el nivel de dominio de la brazada de natación utilizado por los niños que aplicaron este modelo diseñado fue objetivamente mayor en comparación con los mismos indicadores de entrenamiento relacionados con el método tradicional. Conclusiones: Basándonos en la evaluación de la eficiencia de la brazada de natación, creemos que el modelo pedagógico propuesto de enseñar las brazadas básicas de natación competitiva a niños con parálisis cerebral es eficaz.