Pedro Morouço

The Interaction Between Intra-Cyclic Variation of the Velocity and Mean Swimming Velocity in Young Competitive 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 swimmers 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.

Associations Between Dry Land Strength and Power Measurements with Swimming Performance in Elite Athletes: a Pilot Study

Associations Between Dry Land Strength and Power Measurements with Swimming Performance in Elite Athletes: a Pilot Study The main aim of the present study was to analyze the relationships between dry land strength and power measurements with swimming performance. Ten male national level swimmers (age: 14.9 ± 0.74 years, body mass: 60.0 ± 6.26 kg, height: 171.9 ± 6.26, 100 m long course front crawl performance: 59.9 ± 1.87 s) volunteered as subjects. Height and Work were estimated for CMJ. Mean power in the propulsive phase was assessed for squat, bench press (concentric phase) and lat pull down back. Mean force production was evaluated through 30 s maximal effort tethered swimming in front crawl using whole body, arms only and legs only. Swimming velocity was calculated from a maximal bout of 50 m front crawl. Height of CMJ did not correlate with any of the studied variables. There were positive and moderate-strong associations between the work during CMJ and mean propulsive power in squat with tethered forces during whole body and legs only swimming. Mean propulsive power of bench press and lat pull down presented positive and moderate-strong relationships with mean force production in whole body and arms only. Swimming performance is related with mean power of lat pull down back. So, lat pull down back is the most related dry land test with swimming performance; bench press with force production in water arms only; and work during CMJ with tethered forces legs only.

TETHERED SWIMMING CAN BE USED TO EVALUATE FORCE CONTRIBUTION FOR SHORT-DISTANCE SWIMMING PERFORMANCE

Abstract Morouço, PG, Marinho, DA, Keskinen, KL, Badillo, JJ, and Marques, MC. Tethered swimming can be used to evaluate force contribution for short-distance swimming performance. J Strength Cond Res 28(11): 3093–3099, 2014—The purpose of this study was two-fold: (a) to compare stroke and the physiological responses between maximal tethered and free front crawl swimming and (b) to evaluate the contribution of force exertion for swimming performance over short distances. A total of 34 male swimmers, representing various levels of competitive performance, participated in this study. Each participant was tested in both a 30-second maximal tethered swimming test and a 50-m free swimming test. The tethered force parameters, the swimming speed, stroke (stroke rate [SR]), and the physiological responses (increase in blood lactate concentration [&Dgr;BLa], heart rate, and rate of perceived exertion) were recorded and calculated. The results showed no differences in stroke and the physiological responses between tethered and free swimming, with a high level of agreement for the SR and &Dgr;BLa. A strong correlation was obtained between the maximum impulse of force per stroke and the speed (r = 0.91; p < 0.001). Multiple regression analysis revealed that the maximum impulse and SR in the tethered condition explained 84% of the free swimming performance. The relationship between the swimming speed and maximum force tended to be nonlinear, whereas linear relationships were observed with the maximum impulse. This study demonstrates that tethered swimming does not significantly alter stroke and the physiological responses compared with free swimming, and that the maximum impulse per stroke should be used to evaluate the balance between force and the ability to effectively apply force during sprint swimming. Consequently, coaches can rely on tethered forces to identify strength deficits and improve swimming performance over short distances.

Choosing sheep (Ovis aries) as animal model for temporomandibular joint research: Morphological, histological and biomechanical characterization of the joint disc.

Preclinical trials are essential to the development of scientific technologies. Remarkable molecular and cellular research has been done using small animal models. However, significant differences exist regarding the articular behavior between these models and humans. Thus, large animal models may be more appropriate to perform trials involving the temporomandibular joint (TMJ). The aim of this work was to make a morphological (anatomic dissection and white light 3D scanning system), histological (TMJ in bloc was removed for histologic analysis) and biomechanical characterization (tension and compression tests) of sheep TMJ comparing the obtained results with human data. Results showed that sheep processus condylaris and fossa mandibularis are anatomically similar to the same human structures. TMJ disc has an elliptical perimeter, thinner in the center than in periphery. Peripheral area acts as a ring structure supporting the central zone. The disc cells display both fibroblast and chondrocyte-like morphology. Marginal area is formed by loose connective tissue, with some chondrocyte-like cells and collagen fibers in diverse orientations. Discs obtained a tensile modulus of 3.97±0.73MPa and 9.39±1.67MPa, for anteroposterior and mediolateral assessment. The TMJ discs presented a compressive modulus (E) of 446.41±5.16MPa and their maximum stress value (σmax) was 18.87±1.33MPa. Obtained results suggest that these animals should be considered as a prime model for TMJ research and procedural training. Further investigations in the field of oromaxillofacial surgery involving TMJ should consider sheep as a good animal model due to its resemblance of the same joint in humans.

Characterization of speed fluctuation and drag force in young swimmers: a gender comparison.

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.

The Effect 0f Warm-up on Tethered Front Crawl Swimming Forces

The Effect 0f Warm-up on Tethered Front Crawl Swimming Forces This 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.

Relative Contribution of Arms and Legs in 30 s Fully Tethered Front Crawl Swimming

The 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.

Quantification of upper limb kinetic asymmetries in front crawl swimming

This 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.

Fabrication of Poly(ε-caprolactone) Scaffolds Reinforced with Cellulose Nanofibers, with and without the Addition of Hydroxyapatite Nanoparticles.

Biomaterial properties and controlled architecture of scaffolds are essential features to provide an adequate biological and mechanical support for tissue regeneration, mimicking the ingrowth tissues. In this study, a bioextrusion system was used to produce 3D biodegradable scaffolds with controlled architecture, comprising three types of constructs: (i) poly(ε-caprolactone) (PCL) matrix as reference; (ii) PCL-based matrix reinforced with cellulose nanofibers (CNF); and (iii) PCL-based matrix reinforced with CNF and hydroxyapatite nanoparticles (HANP). The effect of the addition and/or combination of CNF and HANP into the polymeric matrix of PCL was investigated, with the effects of the biomaterial composition on the constructs (morphological, thermal, and mechanical performances) being analysed. Scaffolds were produced using a single lay-down pattern of 0/90°, with the same processing parameters among all constructs being assured. The performed morphological analyses showed a satisfactory distribution of CNF within the polymer matrix and high reliability was obtained among the produced scaffolds. Significant effects on surface wettability and thermal properties were observed, among scaffolds. Regarding the mechanical properties, higher scaffold stiffness in the reinforced scaffolds was obtained. Results from the cytotoxicity assay suggest that all the composite scaffolds presented good biocompatibility. The results of this first study on cellulose and hydroxyapatite reinforced constructs with controlled architecture clearly demonstrate the potential of these 3D composite constructs for cell cultivation with enhanced mechanical properties.

Reliability of Tethered Swimming Evaluation in Age Group Swimmers

Abstract The 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 Cronbachs 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.