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- Dry-land strength and conditioning for prepubertal and peripubertal swimmersPublication . Amaro, Nuno; Marinho, Daniel; Marques, MC; Batalha, Nuno; Morouço, PedroSwimming success depends on several factors. The ability to apply in-water force is crucial, particularly in short distances (13,15). Among others methodologies, dry-land strength and conditioning training is a common practice in competitive swimming. [...]
- Characterization of speed fluctuation and drag force in young swimmers: A gender comparisonPublication . Barbosa, Tiago M.; Costa, Mário Jorge; Morais, Jorge; Morouço, Pedro; Moreira, Marc; Garrido, Nuno; Marinho, Daniel; Silva, AntónioThe 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.
- Quantification of upper limb kinetic asymmetries in front crawl swimmingPublication . Morouço, Pedro; Marinho, Daniel; Fernandes, Ricardo J.; Marques, MCThis study aimed at quantifying upper limb kinetic asymmetries in maximal front crawl swimming and to examine if these asymmetries would affect the contribution of force exertion to swimming performance. Eighteen high level male swimmers with unilateral breathing patterns and sprint or middle distance specialists, volunteered as participants. A load-cell was used to quantify the forces exerted in water by completing a 30s maximal front crawl tethered swimming test and a maximal 50 m free swimming was considered as a performance criterion. Individual force-time curves were obtained to calculate the mean and maximum forces per cycle, for each upper limb. Following, symmetry index was estimated and breathing laterality identified by questionnaire. Lastly, the pattern of asymmetries along the test was estimated for each upper limb using linear regression of peak forces per cycle. Asymmetrical force exertion was observed in the majority of the swimmers (66.7%), with a total correspondence of breathing laterality opposite to the side of the force asymmetry. Forces exerted by the dominant upper limb presented a higher decrease than from the non-dominant. Very strong associations were found between exerted forces and swimming performance, when controlling the isolated effect of symmetry index. Results point that force asymmetries occur in the majority of the swimmers, and that these asymmetries are most evident in the first cycles of a maximum bout. Symmetry index stood up as an influencing factor on the contribution of tethered forces over swimming performance. Thus, to some extent, a certain degree of asymmetry is not critical for short swimming performance.
- Relative Contribution of Arms and Legs in 30 s Fully Tethered Front Crawl SwimmingPublication . Morouço, Pedro; Marinho, Daniel; Izquierdo, Mikel; Neiva, Henrique; Marques, MCThe relative contribution of arm stroke and leg kicking to maximal fully tethered front crawl swimming performance remains to be solved. Twenty-three national level young swimmers (12 male and 11 female) randomly performed 3 bouts of 30 s fully tethered swimming (using the whole body, only the arm stroke, and only the leg kicking). A load-cell system permitted the continuous measurement of the exerted forces, and swimming velocity was calculated from the time taken to complete a 50 m front crawl swim. As expected, with no restrictions swimmers were able to exert higher forces than that using only their arm stroke or leg kicking. Estimated relative contributions of arm stroke and leg kicking were 70.3% versus 29.7% for males and 66.6% versus 33.4% for females, with 15.6% and 13.1% force deficits, respectively. To obtain higher velocities, male swimmers are highly dependent on the maximum forces they can exert with the arm stroke (r = 0.77, P < 0.01), whereas female swimmers swimming velocity is more related to whole-body mean forces (r = 0.81, P < 0.01). The obtained results point that leg kicking plays an important role over short duration high intensity bouts and that the used methodology may be useful to identify strength and/or coordination flaws.
- Reliability of Tethered Swimming Evaluation in Age Group SwimmersPublication . Amaro, Nuno; Marinho, Daniel; Batalha, Nuno; Marques, MC; Morouço, PedroThe aim of the present study was to examine the reliability of tethered swimming in the evaluation of age group swimmers. The sample was composed of 8 male national level swimmers with at least 4 years of experience in competitive swimming. Each swimmer performed two 30 second maximal intensity tethered swimming tests, on separate days. Individual force-time curves were registered to assess maximum force, mean force and the mean impulse of force. Both consistency and reliability were very strong, with Cronbach's Alpha values ranging from 0.970 to 0.995. All the applied metrics presented a very high agreement between tests, with the mean impulse of force presenting the highest. These results indicate that tethered swimming can be used to evaluate age group swimmers. Furthermore, better comprehension of the swimmers ability to effectively exert force in the water can be obtained using the impulse of force.
- A systematic review on dry-land strength and conditioning training on swimming performancePublication . Amaro, Nuno; Morouço, Pedro; Marques, MC; Batalha, Nuno; Neiva, Henrique; Marinho, DanielObjectives. — The objective of this review was to examine the effects of dry-land strength and conditioning (S&C) training on swimming, and starts and turns performances. News. — S&C training is a common practice in swimming aiming to enhance performance or to prevent injuries. However, studies regarding the effects of S&C on swimming performance are scarce; the influence of age, gender or competitive level is even scarcer. Prospects and projects. — After a structured literature search, sixteen studies were included in the current review. Of those, seven did not report any positive or negative effects on swimming performance. Contrarily, most studies with positive effects were conducted with older swimmers whereas maximal strength was the most effective methodology for improving swimming performance. S&C plyometric training is suggested to be the most effective method to improve starts and turns. Future Randomized Controlled Trials should be conducted to explore the effects of S&C induced by age and gender, on different swimming distances and techniques, and long-term training effects. Conclusion. — It is recommended that S&C training should be based on maximal strength, ranging from six to twelve weeks of 2 to 4 sessions per week (approximately 24 sessions altogether). In each session, coaches should vary from 2 to 3 sets and 3 to 5 repetitions, according to prescribed intensity. Rest intervals should range between 2 to 5 minutes and the intensity should be from 80 to 90% of 1RM. Particularly regarding improving starts and turns, a S&C training regime ranging from 6 to 8 weeks and with 2 sessions per week is suggested. In each session, swimmers should perform between 1 and 6 sets and 1 and 10 repetitions, according to the established intensity. Rest between sets should range from 60 to 90 seconds. The swimmers in the included studies are mostly men which do not allow to say if the recommendations made are gender-dependent.
- The effect of warm-up on sprinting kinematicsPublication . Morouço, Pedro; Gil, Maria Helena; Neiva, Henrique; Marques, MC; Sousa, António; Marinho, DanielThe purpose of this study was to verify the effects of warm-up on kinematic variables during short distance repeated sprints. Twenty-two college students randomly performed 2 x 30-m running time-trials after warm-up or with no warm-up, in different days. Performance (time-trial) and biomechanical (step length and step frequency) were assessed during both repeated trials. Performance was 0.5% faster after warm-up in the first 30-m time-trial (p = 0.03, d = 0.44), but without differences on step length and frequency. The second sprint was not different between conditions, but it was better than the first sprint in the no warm-up condition. This condition also led to higher changes between the first and second sprint. Thus, the warm-up is suggested to improve maximal running performances and maintaining kinematics more similar throughout the sprints.
- The Effect 0f Warm-up on Tethered Front Crawl Swimming ForcesPublication . Neiva, Henrique; Morouço, Pedro; Silva, António; Marques, MC; Marinho, DanielThis study was conducted to determine the effect of warm-up on high-intensity front crawl tethered swimming and thus to better understand possible variations in the force exerted by the swimmers. Ten male national level swimmers (mean ± SD; age 15.3 ± 0.95 years old, height: 1.73 ± 5.2 m, body mass: 64.3 ± 7.8 kg, Fat mass 8.31 ± 3.1 kg) participated in this study. After a typical competition warm-up, the subjects performed a 30 s tethered swimming all-out effort in front crawl swimming technique. The same test was repeated in the day after but performed without warming up. Capillary blood lactate concentration was assessed before and after the swimming test and the Borg ratings of perceived exertion scale was used. Without a previous warm-up, the mean ± SD values of maximum and mean forces were 299.62 ± 77.56 N and 91.65 ± 14.70 N, respectively. These values were different (p<0.05) from the values obtained with warm-up (351.33 ± 81.85 N and 103.97 ± 19.11 N). Differences were also observed when regarding to the forces relative to body mass. However, the values of lactate net concentrations after the test performed with and without warm-up were not different (6.27 ± 2.36 mmol·l(-1) and 6.18 ± 2.353 mmol·l (-1)) and the same occurs with the values of ratings of perceived exertion (15.90 ± 2.42 and 15.60 ± 2.27). These results suggest an improvement of the maximum and mean force of the swimmer on the tethered swimming due to previous warm-up.
- Biomechanical and bioenergetical evaluation of swimmers using fully-tethered swimming: A qualitative reviewPublication . Amaro, Nuno; Morouço, Pedro; Marques, MC; Fernandes, Ricardo J.; Marinho, DanielIt is presented a qualitative review of the specialized literature on fully-tethered swimming, with the scopes of summarizing and highlighting published knowledge, identifying its gaps and limitations, and motivate future research. The major research conclusions can be summarized as follows: (i) tethered swimming is a reliable test to evaluate force exerted in water by swimmers; (ii) higher maximum values of force are obtained in breaststroke and butterfly, while average values are higher in front crawl; (iii) tethered forces present moderate to strong relationships with swimming velocity, and associations between forces diminish as swimming distance increases; (iv) 30 s maximal tethered swimming may be used as an adaptation of Wingate test for swimming; (v) differences in stroke mechanics can occur in tethered swimming but there is no evidence to suggest that they affect swimming performance; (vi) Tethered swimming is a valid methodology to evaluate aerobic energy contribution in swimming and recent investigations concluded that it can also provide information on the anaerobic contribution. Based on and stimulated by current knowledge, further research should focus on the following topics: (i) the usefulness of tethered swimming as a valid tool to evaluate other swimming techniques; (ii) differences in force parameters induced by gender or competitive level; (iii) defining accurate variables for estimation of anaerobic power and/or capacity using tethered swimming; (iv) bilateral asymmetries in exerted forces, and corresponding influence of breathing; (v) relative contribution of arms and legs for whole-body propelling forces.
- The variations on the aerodynamics of a world-ranked wheelchair sprinter in the key-moments of the stroke cyclePublication . Forte, Pedro; Marinho, Daniel; Morais, Jorge; Morouço, Pedro; Barbosa, Tiago M.Biomechanics plays an important role helping Paralympic sprinters to excel, having the aerodynamic drag a significant impact on the athlete's performance. The aim of this study was to assess the aerodynamics in different key-moments of the stroke cycle by Computational Fluid Dynamics. A world-ranked wheelchair sprinter was scanned on the racing wheelchair wearing his competition gear and helmet. The sprinter was scanned in three different positions: (i) catch (hands in the 12h position on the hand-rim); (ii) the release (hands in the 18h position on the hand-rim) and; (iii) recovery phase (hands do not touch the hand-rim and are hyperextended backwards). The simulations were performed at 2.0, 3.5, 5.0 and 6.5 m/s. The mean viscous and pressure drag components, total drag force and effective area were retrieved after running the numerical simulations. The viscous drag ranged from 3.35 N to 2.94 N, pressure drag from 0.38 N to 5.51 N, total drag force from 0.72 N to 8.45 N and effective area from 0.24 to 0.41 m2. The results pointed out that the sprinter was submitted to less drag in the recovery phase, and higher drag in the catch. These findings suggest the importance of keeping an adequate body alignment to avoid an increase in the drag force.