The Strategy of Muscular Pre-Tension during Initial Block Phase in Swimming Grab Start (original) (raw)
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Effective Swimmer’s Action during the Grab Start Technique
PLOS ONE, 2015
The external forces applied in swimming starts have been often studied, but using direct analysis and simple interpretation data processes. This study aimed to develop a tool for vertical and horizontal force assessment based on the swimmers' propulsive and structural forces (passive forces due to dead weight) applied during the block phase. Four methodological pathways were followed: the experimented fall of a rigid body, the swimmers' inertia effect, the development of a mathematical model to describe the outcome of the rigid body fall and its generalization to include the effects of the inertia, and the experimental swimmers' starting protocol analysed with the inclusion of the developed mathematical tool. The first three methodological steps resulted in the description and computation of the passive force components. At the fourth step, six well-trained swimmers performed three 15 m maximal grab start trials and three-dimensional (3D) kinetic data were obtained using a six degrees of freedom force plate. The passive force contribution to the start performance obtained from the model was subtracted from the experimental force due to the swimmers resulting in the swimmers' active forces. As expected, the swimmers' vertical and horizontal active forces accounted for the maximum variability contribution of the experimental forces. It was found that the active force profile for the vertical and horizontal components resembled one another. These findings should be considered in clarifying the active swimmers' force variability and the respective geometrical profile as indicators to redefine steering strategies.
ISBS-Conference …, 2008
Assuming that the forces recorded during the CMJ are related to the muscular leg force and power, the aim of our study is to investigate why in previous studies these recorded forces were not correlated with the forces recorded during the swimming start. A simulated start was recorded on land to try to find if a more similar jumping technique, showed a force related to the swimming start variables. To isolate the start variables in comparison to our previous studies, the swimmer performed only a gliding displacement until 10 m after the water entry without any type of propulsive underwater movements in our present study. We found no difference from the results of previous studies in spite of including simulated grab-start recordings in the lab. Only the horizontal force n the swimming start correlated to five-metre time and the first five-metre mean velocity. The difference and non-relationships when the swimmer applies force against gravity or with gravity have still not resolved.
Body Compositionand Kinematic Analysisofthe Grab Startin Youth Swimmers
The purposes of this study were to compare the kinematic variables in youth swimmers during the grab start between sexes and to investigate the relationship between body composition and kinematic variables of the participants. Six female (Mage = 13.71 ± 0.49 yrs) and seven male (Mage = 14.00 ± 1.07 yrs) swimmers participated in this study. All participants were required to perform grab start tests in random order (three trials by each participant), while the best attempt was analyzed. Nineteen kinematic parameters consisting of block time, flight time, flight distance, total time, total distance, horizontal and vertical displacement of the center of mass (CM) at take-off, horizontal and vertical displacement of the CM at entry, height of take-off and entry, relative height of take-off, horizontal and vertical velocity of the CM at take-off, horizontal and vertical velocity of the CM at entry, angle of take-off, angle of entry and angle of knee at block were analyzed. Out of the 19 evaluated kinematic parameters, a statistical difference between the female and male group was found only in the total distance. Therefore, both female and male groups are considered as only one group and merged after analyzing the results. Statistical analysis showed positive and negative correlations between horizontal / vertical velocity of CM at take-off and several kinematic variables (e.g. angle of entry (rhorizontal = -.868, p=.000 / rvertical = .591, p=.02), total distance (rhorizontal = .594, p=.02 / rvertical = .54, p=.04), and height of take-off (rvertical = .888, p=.000), respectively). On the other hand, positive and negative correlations were found between somatotype components and several kinematic variables (e.g. horizontal displacement of CM at entry (rendomorphy = -.626, p=.013), angle of entry (rmesomorphy = -.686, p=.005 / rectomorphy = .52, p=.047), total distance (rendomorphy = -.626, p=.012), and height of take-off (rendomorphy = -.633, p=.011 / rectomorphy = .515, p=.05)). In conclusion, results show that in order to be successful at grab start performance, a swimmer should target to get higher horizontal velocity of CM at take-off and optimize the angle of take-off so this movement form supplies more total distance to the swimmer. Coaches should consider improving start performance and adding start training to regular training sessions. Moreover, youth male and female swimmers can participate together in the grab start training.
Kinematical and neuromuscular aspects related to performance during the swimming start
The aim of this study was to investigate the association between the performance of the start off the swimming block with kinematical and neuromuscular parameters (flight distance and flight time). Ten male swimmers (26.4 ± 6.6 years, 76.4 ± 6.6 kg, 1.81 ± 0.07 m) participated in the study. A video camera (30 Hz) was used to obtain the kinematic variables: flight distance, flight time, maximum height, start angle and entry angle. Muscle power was assessed via the performance of a Squat Jump on a force plate. Jump height, power and peak of velocity were analyzed. Pearson correlation was used to correlate kinematic and neuromuscular variables with starting performance. The level of significance was set at 5%. A significant correlation between the starting angle and both the flight distance (r = -0.59) and the flight time (r = 0.88) were found; also, a positive correlation was found between maximum height and flight time (r = 0.59). No significant correlation between swimming start per...
The kinematic analysis of the grab and track start in swimming
2010
The winner in swimming is often decided by hundredths of a second, and therefore, all the elements of the race must be practiced. The start in swimming, together with the other elements of the race, is very important for achieving better results in competitions. Nowadays, swimmers use two start techniques: the grab and track start. The aim of this study is to determine the statistically significant differences in certain kinematic parameters between the grab and track start among competitive swimmers, cadet selection. The sample consisted of 6 competitive swimmers, 15 years of age ± SD, who belong to the cadet selection of the swimming club 'Argiroupoli Nautical Club' from Athens (Greece). Three swimmers performed the grab start, while the other three performed the track start. This study involved 8 kinematic parameters: flight length (FL), flight time (FT), ascending angle (AA), angle of entry (AE), velocity of the centre of mass at take-off (VCMT), velocity of head movemen...
ISBS-Conference …, 2009
The purpose of our study was to develop a system to improve the swimmer's starting technique integrating force and video data. A group of elite swimmers (n=17) took part in the study. Cinematic and kinetic variables of the start technique during the block, flight, and swimming phases until the end of the first 10 m were analysed. The horizontal velocity during the take-off (3,96 m/s) and peak horizontal force applied (917,2 N) did not correlate with the 5 m time (1,79 s). Only the value of the velocity vector before the moment of the hand entry (4,63 m/s) correlated with the 5 m time (r=-0.56). The transformation of the velocity components of the swimmer's centre of mass during the flight to a high horizontal gliding speed seems the more complex problem for the swimmer to resolve and where our future research will be directed.
A Kinetic and Kinematic Comparison of the Grab and Track Starts in Competitive Swimming
Medicine & Science in Sports & Exercise, 1999
Based on data collected over a period of years Maglischo (1993) noted that "improving the start can reduce race times by at least 0.10 second" (p. 544). Therefore it is beneficial to the outcome of a race to direct attention to maximizing the effectiveness of the racing start. The primary purpose of this study therefore was to compare kinetic and kinematic components of the grab and track style starts. During the past two decades extensive kinematic research has been done using cinematography. These studies used time, velocity, displacement, and the measure of angles (i.e. at takeoff and entry) to measure the relative effectiveness of various racing starts. Conversely, there has been limited analysis of racing starts using kinetic measurements.