Evidence on the role of propulsion compared to drag in swimming, based on experimental settings, is still lacking. However, higher levels of propulsion seem to lead to faster swimming velocities. The aim of this study was to understand the variation in a set of kinematic and kinetic variables between two swimming sections and their relationship to swimming velocity. The sample consisted of 15 young adult recreational swimmers (8 males: 20.84 ± 2.03 years; 7 females: 20.13 ± 1.90 years). Maximum swimming velocity and a set of kinematic and kinetic variables were measured during two consecutive sections of the swimming pool. Differences between sections were measured and the determinants of swimming velocity were analyzed. Swimming velocity, propulsive force, and the other kinematic and kinetic variables did not change significantly (p < 0.05) between sections (only the intra-cyclic fluctuation of swimming velocity decreased significantly, p = 0.005). The modeling identified the propulsive force, stroke length, and active drag coefficient as the determinants of swimming velocity. Swimming velocity was determined by the interaction of kinematic and kinetic variables, specifically propulsive force and active drag coefficient.

There is scarce information about what characterizes the swimming speed in the butterfly stroke and the role of thrust in its characterization and prediction. The aim of this study was to compare the fastest and poorest butterfly swimmers based on a set of anthropometric, kinematic, and kinetic variables and to identify the swimming speed predictors. Eight young male swimmers were divided into two equal groups (each group comprising four swimmers). The swimming speed, as well as a set of anthropometric, kinematic, and kinetic variables, were measured. The swimming speed presented significant differences between the groups (p = 0.011, d = 2.18). The stroke frequency (kinematics, p = 0.027, d = 1.69) and thrust (kinetics, p = 0.034, d = 1.57) also presented significant differences between the groups. The swimming speed presented significant correlations with the stroke index (r_s = 0.83, p = 0.011) and thrust (r_s = 0.83, p = 0.011). The swimming speed was predicted by a combination of the stroke frequency and thrust (R² = 0.84, p = 0.010). Coaches and athletes must be aware that combining fast stroke frequencies and the generation of greater thrust leads to the fastest swimming speeds.

Background : Velocity-monitored resistance training (RT) marked a significant advancement in the RT paradigm by providing precise information about the loads applied. Objectives : This study compared the acute effects of velocity-monitored RT with 10% versus 20% velocity loss (VL) on hemodynamic, metabolic, and mechanical parameters in older adults. Methods : Twenty-nine older adults (81 ± 8 years) randomly performed two training protocols separated by a 1-week rest period: three sets of 10% VL (VL10) or 20% VL (VL20) at 60% of one-repetition maximum in chest and leg press exercises. Before and immediately after each protocol, we collected the systolic and diastolic blood pressure, heart rate, and blood lactate. Furthermore, we recorded the fastest velocity and peak power reached against the same weight before and after each resistance exercise. Results : The analysis revealed significant differences between protocols in VL (∼12% vs. ∼21%, p < .001) and total repetitions (∼12 vs. ∼24, p < .001). Furthermore, in comparison with the VL10 protocol, the VL20 elicited a higher increase in blood lactate (29% vs. 11%, p < .001) and a reduction in chest press peak power (−4% vs. +3%, p < .001) and chest press velocity (−4% vs. +2%, p < .001). There were no differences between protocols on systolic and diastolic blood pressure and heart rate. Conclusion : This study shows that a VL20 magnitude induces higher metabolic and mechanical stress than a VL10 magnitude, whereas the latter can preserve mechanical performance in older adults. Implications : Implementing velocity-monitored RT ensured regulation of the training load, uniform effort, and objective assessment of training effect.