The aim of this study was to compare the speed fluctuation and the drag force in young swimmers between genders. Twenty-three young pubertal swimmers (12 boys and 11 girls) volunteered as subjects. Speed fluctuation was measured using a kinematical mechanical method (i.e., speedo-meter) during a maximal 25-m front crawl bout. Active drag, active drag coefficient and power needed to overcome drag were measured with the velocity perturbation method for another two maximal 25 m front crawl bouts with and without the perturbation device. Passive drag and the passive drag coefficient were estimated using the gliding decay velocity method after a maximal push-off from the wall while being fully immersed. The technique drag index was also assessed as a ratio between active and passive drag. Boys presented meaningfully higher speed fluctuation, active drag, power needed to overcome drag and technique drag index than the girls. There were no significant gender differences for active drag coefficient, passive drag and passive drag oefficient. There were positive and moderate-strong associations between active drag and speed fluctuation when controlling the effects of swim velocity. So, increasing speed fluctuation leads to higher drag force values and those are even higher for boys than for girls.

The aim of this study was to compare the speed fluctuation and the drag force in young swimmers between genders. Twenty-three young pubertal swimmers (12 boys and 11 girls) volunteered as subjects. Speed fluctuation was measured using a kinematical mechanical method (i.e., speedo-meter) during a maximal 25-m front crawl bout. Active drag, active drag coefficient and power needed to overcome drag were measured with the velocity perturbation method for another two maximal 25 m front crawl bouts with and without the perturbation device. Passive drag and the passive drag coefficient were estimated using the gliding decay velocity method after a maximal push-off from the wall while being fully immersed. The technique drag index was also assessed as a ratio between active and passive drag. Boys presented meaningfully higher speed fluctuation, active drag, power needed to overcome drag and technique drag index than the girls. There were no significant gender differences for active drag coefficient, passive drag and passive drag coefficient. There were positive and moderate- strong associations between active drag and speed fluctuation when controlling the effects of swim velocity. So, increasing speed fluctuation leads to higher drag force values and those are even higher for boys than for girls.

The role of drag force in competitive swimming is one of the main topics for researchers and field practitioners as it allows enhancing performance. The development of “flow chart” models confirming the relationships between drag force and other determinant variables was never attempted in competitive swimming. Moreover, main research groups dedicate little attention to age-group swimming. PURPOSE: The aim was to develop a structural equation modeling (i.e., path-flow analysis model) for active drag force (Da) based on anthropometric, hydrodynamic and biomechanical determinants in young swimmers. The theoretical model was developed according to main review papers about these determinants. METHODS: Sixteen male swimmers (12.50±0.51 years-old; Tanner stages’ 1 -2) were evaluated. It was assessed: (i) anthropometrical variables such as body mass, height, frontal surface area (FSA); (ii) hydrodynamic variables including drag coefficient and Da with the velocity perturbation method; (iii) the biomechanical variables stroke length (SL), stroke frequency (SF) and swimming velocity after a maximal 25-m bout. It was computed the Spearmen´s Rank Correlation Coefficient between exogenous and endogenous variables. Path-flow analysis was performed with the estimation of linear regression standardized coefficients between exogenous and endogenous variables. When appropriate, according to the theoretical model, simple or multiple linear regression models were computed. The standardized regression coefficients (β) were considered and the significance of each β was assessed with the student’s t-test (p<0.05). The effect size of the disturbance term for a given endogenous variable, which reflects unmeasured variables was 1 -R2. To verify the model fit, root mean square residual was computed (RMSR < 0.1). RESULTS: The Da presented significant association with all exogenous variables, except for SL and SF. Confirmatory model excluded the FSA (RMSR > 0.1). Even so, 95% of Da was explained by remaining variables in the model. CONCLUSION: Confirmatory path-flow model can be considered as not suitable of the theory. For a near future it is advice to develop new FSA estimation equations specific for young swimmers rather than using models developed with adult/elite swimmers.

This study aimed to synthesise the body of knowledge on kinematics, active drag and energetics determinants of energy cost variability in the breaststroke technique. Methodological procedures considering the standards for systematic reviews according to the ‘“Preferred Reporting Items for Systematic Reviews and Meta-Analyses”’ were employed. Searches were conducted in four prominent databases. A total of 1,464 articles were identified, of which 201 met the eligibility criteria. After evaluation, 73 articles were included for synthesis in this review. The included studies had a mean score (± SD) of 9.14 ± 1.76 points regarding the quality assessment. The present review identified three distinct domains of variables: kinematics (including stroke kinematics and coordination parameters), active drag, and energetics. The findings underscored the pivotal role of stroke kinematics, including stroke rate, stroke length, stroke index, and intra-cyclic variations of velocity, in influencing energy cost during breaststroke swimming. Additionally, the analysis highlighted the significance of propulsive and non-propulsive phases, arm-to-leg timing, and buoyancy in breaststroke technique. Notably, breaststroke exhibited higher values of active drag, frontal area, and energy cost, while maintaining lower velocity compared to other swimming techniques. Overall, this synthesis of literature highlights the holistic nature of energy cost in breaststroke swimming.

In swimming, it is necessary to understand and identify the main factors that are important to reduce active drag and, consequently, improve the performance of swimmers. However, there is no up-to-date review in the literature clarifying this topic. Thus, a systematic narrative review was performed to update the body of knowledge on active drag in swimming through numerical and experimental methods.