The purpose of this study was to analyze the relationships between musical cadence and the physiologic adaptations to basic head-out aquatic exercises. Fifteen young and clinically healthy women performed, immersed to the breast, a cardiovascular aquatic exercise called the "rocking horse." The study design included an intermittent and progressive protocol starting at a 90 b.min(-1) rhythm and increasing every 6 minutes, by 15 b.min(-1), up to 195 b.min(-1) or exhaustion. The rating of perceived effort (RPE) at the maximal heart rate achieved during each bout (HRmax), the percentage of the maximal theoretical heart rate estimated (%HRmax), and the blood lactate concentration ([La-]) were evaluated. The musical cadence was also calculated at 4 mmol.L(-1) of blood lactate (R4), the RPE at R4 (RPE@R4), the HR at R4 (HR@R4), and the %HRmax at R4 (%HRmax@R4). Strong relationships were verified between the musical cadence and the RPE (R2 = 0.85; p < 0.01), the HRmax (R2 = 0.66; p < 0.01), the %HRmax (R = 0.61; p < 0.01), and the [La-] (R2 = 0.54; p < 0.01). The R4 was 148.13 +/- 17.53 b.min, the RPE@R4 was 14.53 +/- 2.53, the HR@R4 was 169.33 +/- 12.06 b.min, and the %HRmax@R4 was 85.53 +/- 5.72%. The main conclusion is that increasing musical cadence created an increase in the physiologic response. Therefore, instructors must choose musical cadences according to the goals of the session they are conducting to achieve the desired intensity.

The aim was to develop a path-flow analysis model for young swimmers' performance based on biomechanical and energetic parameters, using structural equation modeling. Thirty-eight male young swimmers served as subjects. Performance was assessed by the 200-m freestyle event. For biomechanical assessment the stroke length, the stroke frequency and the swimming velocity were analyzed. Energetics assessment included the critical velocity, the stroke index and the propulsive efficiency. The confirmatory model explained 79% of swimming performance after deleting the stroke index-performance path, which was nonsignificant (SRMR = 0.06). As a conclusion, the model is appropriate to explain performance in young swimmers.

The aim of this study was to compute and validate trunk transverse surface area (TTSA) estimation equations to be used assessing the swimmer's drag force according to competitive level by gender. One group of 130 swimmers (54 females and 76 males) was used to compute the TTSA estimation equations and another group of 132 swimmers (56 females and 76 males) were used for its validations. Swimmers were photographed in the transverse plane from above, on land, in the upright and hydrodynamic position. The TTSA was measured from the swimmer's photo with specific software. It was also measured the height, body mass, biacromial diameter, chest sagital diameter (CSD) and the chest perimeter (CP). With the first group of swimmers it was computed the TTSA estimation equations based on stepwise multiple regression models from the selected anthropometrical variables. The TTSA prediction equations were significant and with a prediction level qualitatively considered as moderate. All equations included only the CP and the CSD in the final models. In all prediction models there were no significant differences between assessed and estimated mean TTSA. Coefficients of determination for the linear regression models between assessed and estimated TTSA were moderate and significant. More than 80% of the plots were within the 95% interval confidence for the Bland-Altman analysis in both genders. So, TTSA estimation equations that are easy to be computed by coached and researchers were developed. All equations accomplished the validation criteria adopted.

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 25m 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.

In the last decades head-out aquatic exercises became one of the most important physical activities within the health system. Massive research has been produced throughout these decades in order to better understand the role of head-out aquatic exercises in populations' health. Such studies aimed to obtain comprehensive knowledge about the acute and chronic response of subjects performing head-out aquatic exercises. For that, it is assumed that chronic adaptations represent the accumulation of acute responses during each aquatic session. The purpose of this study was to describe the "state of the art "about physiological assessment of head-out aquatic exercises based on acute and chronic adaptations in healthy subjects based on a qualitative review. The main findings about acute response of head-out aquatic exercise according to water temperature, water depth, type of exercise, additional equipment used, body segments exercising and music cadence will be described. In what concerns chronic adaptations, the main results related to cardiovascular and metabolic adaptations, muscular strength, flexibility and body composition improvements will be reported. Key pointsSeveral papers reported consistent and significant improvement in physical fitness (e.g., aerobic capacity, muscular strength, flexibility and body composition) after a program of head-out aquatic exercise with at least eight weeks.Chronic adaptations to head-out aquatic exercise programs are the cumulative result of appropriate acute responses during the exercise session.Appropriate acute adaptations can be obtained taking into account the water temperature, water depth, type of exercise and its variants, the equipment used and the segmental cadence according to the subjects' profile.

The aim of this study was to compare the swimming hydrodynamics assessed with experimental and analytical procedures, as well as, to learn about the relative contributions of the friction drag and pressure drag to total passive drag. Sixty young talented swimmers (30 boys and 30 girls with 13.59±0.77 and 12.61±0.07 years-old, respectively) were assessed. Passive drag was assessed with inverse dynamics of the gliding decay speed. The theoretical modeling included a set of analytical procedures based on naval architecture adapted to human swimming. Linear regression models between experimental and analytical procedures showed a high correlation for both passive drag (Dp = 0.777*Df+pr; R2 = 0.90; R2a = 0.90; SEE = 8.528; P<0.001) and passive drag coefficient (CDp = 1.918*CDf+pr; R2 = 0.96; R2a = 0.96; SEE = 0.029; P<0.001). On average the difference between methods was -7.002N (95%CI: -40.480; 26.475) for the passive drag and 0.127 (95%CI: 0.007; 0.247) for the passive drag coefficient. The partial contribution of friction drag and pressure drag to total passive drag was 14.12±9.33% and 85.88±9.33%, respectively. As a conclusion, there is a strong relationship between the passive drag and passive drag coefficient assessed with experimental and analytical procedures. The analytical method is a novel, feasible and valid way to gather insight about one's passive drag during training and competition. Analytical methods can be selected not only to perform race analysis during official competitions but also to monitor the swimmer's status on regular basis during training sessions without disrupting or time-consuming procedures.

The aim of this article was to compare swimming power output between boys and girls and to model the relationship between swimming power output and sprinting performance in young swimmers. One hundred young swimmers (49 boys and 51 girls, aged between 11 and 13 years) underwent a test battery including anthropometrics (body mass, height, arm span [AS], and trunk transverse surface area), kinematic and efficiency (velocity, stroke frequency, stroke length, speed fluctuation, normalized speed fluctuation, stroke index, and Froude efficiency), hydrodynamics (active drag and active drag coefficient), and power output (power to overcome drag, power to transfer kinetic energy to water, and external power) assessments and sprinting performance (official 100 freestyle race). All variables but the trunk transverse surface area, stroke length normalize to AS, speed fluctuation, active drag coefficient, and Froude efficiency were significantly higher in boys than in girls with moderate-strong effects. Comparing both sexes but controlling the effect of the sprinting performance, most variables presented a no-significant variation. There was a significant and strong relationship between power output and sprinting performance: y = 24.179x (R = 0.426; standard error of estimation = 0.485; p < 0.001). As a conclusion, boys presented better performances than girls because of their higher power output. There is a cubed relationship between power output and sprinting performance in young swimmers.

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 this article has been to classify swimmers based on kinematics, hydrodynamics, and anthropometrics. Sixty-seven young swimmers made a maximal 25 m front-crawl to measure with a speedometer the swimming velocity (v), speed-fluctuation (dv) and dv normalized to v (dv/v). Another two 25 m bouts with and without carrying a perturbation device were made to estimate active drag coefficient (CDa). Trunk transverse surface area (S) was measured with photogrammetric technique on land and in the hydrodynamic position. Cluster 1 was related to swimmers with a high speed fluctuation (ie, dv and dv/v), cluster 2 with anthropometrics (ie, S) and cluster 3 with a high hydrodynamic profile (ie, CDa). The variable that seems to discriminate better the clusters was the dv/v (F=53.680; P<.001), followed by the dv (F=28.506; P<.001), CDa (F=21.025; P<.001), S (F=6.297; P<.01) and v (F=5.375; P=.01). Stepwise discriminant analysis extracted 2 functions: Function 1 was mainly defined by dv/v and S (74.3% of variance), whereas function 2 was mainly defined by CDa (25.7% of variance). It can be concluded that kinematics, hydrodynamics and anthropometrics are determinant domains in which to classify and characterize young swimmers' profiles.

The biophysical determinants related to swimming performance are one of the most attractive topics within swimming science. The aim of this paper was to do an update of the "state of art" about the interplay between performance, energetic and biomechanics in competitive swimming. Throughout the manuscript some recent highlights are described: (i) the relationship between swimmer's segmental kinematics (segmental velocities, stroke length, stroke frequency, stroke index and coordination index) and his center of mass kinematics (swimming velocity and speed fluctuation); (ii) the relationships between energetic (energy expenditure and energy cost) and swimmer's kinematics; and (iii) the prediction of swimming performance derived from above mentioned parameters.