José Arturo Abraldes

Anthropometry and throwing velocity in elite water polo by specific playing positions

Anthropometry and throwing velocity in elite water polo by specific playing positions The purposes of this study were threefold: to present the specific physical structure of elite water polo players by playing positions, to access its throwing velocity in different conditions (without goalkeeper, with goalkeeper and with previous displacement), and to observe the relationships between the assessed anthropometric and throwing velocity parameters. Nineteen water polo players of the Spanish National Team (nine offensive wings, five center back and five center forwards) were evaluated. The anthropometric profile (particularly the lengths, breaths, girths and skinfolds) was obtained according to the International Working Group of Kinanthropometry, and the throwing velocity was assessed in 3 × 2 maximal intensity shoots (3 min interval) from the penalty line using a radar. It was possible to observe higher values of body mass, BMI, and muscle mass of the center forwards compared to the wings, and foot length of the center backs compared with the wings, reflecting a specific physical profile for each playing position. However, no difference was found between groups regarding the breadths values. In addition, the somatotype of the wings is a balanced mesomorph, and the center backs and center forwards endo-mesomorphs. Despite center backs have higher hand grip values in comparison with wings, no differences were observed between specific playing positions in each throwing condition, as well as between conditions in each specific playing position. Moreover, observing the correlation coefficient values between anthropometric and throwing velocity variables by specific position for the three throwing conditions, a higher number of relationships was found for the center backs and center forwards rather than for the wings. When the total sample was analysed, a superior number of relationships was observed between the studied parameters in throwing with goalkeeper situation. These data reflects the dependence of the throwing skill on the anthropometric characteristics of water polo players.

Behavioural variability and motor performance: Effect of practice specialization in front crawl swimming.

The aim was to examine behavioural variability within and between individuals, especially in a swimming task, to explore how swimmers with various specialty (competitive short distance swimming vs. triathlon) adapt to repetitive events of sub-maximal intensity, controlled in speed but of various distances. Five swimmers and five triathletes randomly performed three variants (with steps of 200, 300 and 400m distances) of a front crawl incremental step test until exhaustion. Multi-camera system was used to collect and analyse eight kinematical and swimming efficiency parameters. Analysis of variance showed significant differences between swimmers and triathletes, with significant individual effect. Cluster analysis put these parameters together to investigate whether each individual used the same pattern(s) and one or several patterns to achieve the task goal. Results exhibited ten patterns for the whole population, with only two behavioural patterns shared between swimmers and triathletes. Swimmers tended to use higher hand velocity and index of coordination than triathletes. Mono-stability occurred in swimmers whatever the task constraint showing high stability, while triathletes revealed bi-stability because they switched to another pattern at mid-distance of the task. Finally, our analysis helped to explain and understand effect of specialty and more broadly individual adaptation to task constraint.

Influence of Physical Aspects And Throwing Velocity in Opposition Situations in Top-Elite and Elite Female Handball Players

Abstract The relationship between anthropometric and physical characteristics of female handball players and throwing velocity is considered an important factor in handball performance. The aim of this study was to examine key differences in anthropometric and fitness characteristics between top elite and elite female players competing in the first Spanish handball league. A total of 89 players from the first Spanish handball league were divided into two groups, top elite (38) and elite (51) players, and assessed for anthropometric and fitness characteristics (throwing velocity, vertical jump and hand grip strength). A Student’s t-test was used to determine whether a statistically significant difference between the two different levels of play occurred. Significant differences were found in age, body height, body mass, arm span, muscle mass, different girths (tensed and flexed arm, forearm, wrist, ankle), dominant hand width and length, different breadths (biacromial, bitrochanteric, bistyloid breadth and biepicondylar humerus) and fitness characteristics (hand grip strength and throwing velocity for different positions). Top elite players compared to elite players showed differences in anthropometric characteristics which were mainly located in the upper limbs and mostly were nonmodifiable aspects by training. Furthermore, the best players were able to maintain a high throwing velocity in different tactical situations.

Modelling and Predicting Backstroke Start Performance Using Non-Linear And Linear Models

Abstract Our aim was to compare non-linear and linear mathematical model responses for backstroke start performance prediction. Ten swimmers randomly completed eight 15 m backstroke starts with feet over the wedge, four with hands on the highest horizontal and four on the vertical handgrip. Swimmers were videotaped using a dual media camera set-up, with the starts being performed over an instrumented block with four force plates. Artificial neural networks were applied to predict 5 m start time using kinematic and kinetic variables and to determine the accuracy of the mean absolute percentage error. Artificial neural networks predicted start time more robustly than the linear model with respect to changing training to the validation dataset for the vertical handgrip (3.95 ± 1.67 vs. 5.92 ± 3.27%). Artificial neural networks obtained a smaller mean absolute percentage error than the linear model in the horizontal (0.43 ± 0.19 vs. 0.98 ± 0.19%) and vertical handgrip (0.45 ± 0.19 vs. 1.38 ± 0.30%) using all input data. The best artificial neural network validation revealed a smaller mean absolute error than the linear model for the horizontal (0.007 vs. 0.04 s) and vertical handgrip (0.01 vs. 0.03 s). Artificial neural networks should be used for backstroke 5 m start time prediction due to the quite small differences among the elite level performances.

Using Wavelet Transform for Speed Fluctuation Analysis During Manikin Carry with Fins

Background : Wavelet analysis has been used to locate speed variation changes in swimmers, but this elaborated technique was not so far tested in lifesavers carrying a manikin and using one upper limb and fins for propulsion. Objective : Our purpose was to examine the feasibility of using the wavelet analysis to locate time-points of speed variation changes in a manikin carry lifesaving race using stiff and fiber fins. Method : Fourteen male lifesavers with a mean age of 20.79±4.93 years performed two 25 m all-out manikin carry swimming races using one upper limb and stiff or fiber fins for propulsion. Speed was recorded with a speedometer and its variation was analysed using a wavelet transform analysis. Video recordings were used to measure stroke rate and stroke length within each race. Results : Wavelet analysis detected, for some lifesavers, one (stiff: 10.50±1.29 vs. fiber: 9.75±0.50 s; p>0.05) and, for other lifesavers, two time-points (stiff: 6.75±0.96 and 11.50±1.29; fiber: 7.00±1.41 and 12.00±1.83 s; p>0.05) of speed variation changes. Mean speed was no different with fin types (stiff: 1.38±0.06 vs. fiber: 1.42±0.09 m∙s-1; p>0.05), as well as average, maximum and minimum speed. Stroke rate, stroke length and stroke index did not change within each race. Conclusion : Wavelet analysis was effective in detecting one and two time-points of speed variation changes within a short duration manikin carry race independently of the type of fins used. Fiber and stiff fins showed similar biomechanical and speed variations within race changes.