Grab Start Research Articles

The effects of lower extremity muscle strength characteristics on grab and track start performance in young competitive swimmers

BACKGROUND: Limited data exist regarding segmental contributions of lower extremity muscles to the swim start performance during different start techniques in young swimmers. OBJECTIVE: To determine the differences in the kinematic parameters between the grab start (GS) and track start (TS) techniques and assess the interactions between the lower limb muscle strength and swim start performance. METHODS: A total of 40 swimmers, 20 girls (age: 13.70 ± 1.80 y, height: 161.65 ± 8.28 cm, body weight: 53.70 ± 8.65 kg) and 20 boys (age: 13.90 ± 1.45 y, height: 160.95 ± 12.70 cm, body weight: 52.95 ± 12.64 kg), 13–16 y of age, at the competitive level were recruited. Ankle, hip, and knee muscles were tested isokinetically at 60∘/s and the tests were spread over 24 h to avoid fatigue. Several elements relating to GS and TS were measured using a motion pick-up video camera. RESULTS: The angle of entry (EA) at water and knee joint angle (KA) were significantly greater during GS both for boys (EA: 44.18 ± 1.07∘ vs. 43.03 ± 1.28∘; KA: 112.10 ± 15.25∘ vs. 107.21 ± 21.13)∘ and girls (45.09 ± 1.28∘ vs. 43.36 ± 1.55∘; KA: 103.08 ± 11.21∘ vs. 97.45 ± 19.52∘, p< 0.05). Flight time (FT), flight distance (FD), KA, and flight velocity (FV) were significantly higher for boys both during GS and TS, whereas EA was significantly lower for boys during GS compared to girls (p< 0.05). Lower limb strength performance was positively significantly correlated with FT, FD, and FV both during GS and TS (p< 0.05). Hip muscle strength was inversely correlated with the EA both during GS and TS (p< 0.05). The combination of the knee, ankle, and hip extensor and flexor muscle strengths had a greater effect during GS (35% vs. 29%) in RT, (48% vs. 46%) in FT, (59% vs. 57%) in FD, and (63% vs. 57%) in FV compared to the TS. CONCLUSIONS: Incorporating lower body strength training into the swimming training schedule may improve swim start performance variables during grab start and track start techniques.

Key determinants of time to 5 m in different ventral swimming start techniques

The aim of this study was to determine the biomechanical parameters that explain ventral start performance in swimming. For this purpose, 13 elite swimmers performed different variants of the ventral start technique. Two-dimensional video analyses of the aerial and underwater phases were used to assess 16 kinematic parameters from the starting signal to 5 m, and an instrumented starting block was used to assess kinetic data. A Lasso regression was used to reduce the number of parameters, providing the main determinants to starting performance, revealing different combinations of key determinants, depending on the variant (r² ≥ 0.90), with flight distance being the most relevant to all variants (r ≤ −0.80; p < .001). Also, special attention should be given to the total horizontal impulse in the grab start (r = −0.79; p < .001) and to the back foot action in the track and kick starts (r ≤ 0.61; p < .001). In addition, we provide two equations that could be easily used to predict starting performance by assessing block time and flight time (r² = 0.66) or block time and flight distance (r² = 0.83). These data provide relevant contributions to the further understanding of the biomechanics of swimming starts as well as insights for performance analysis and targeted interventions to improve athlete performance.

Which start is faster in finswimming?

Finswimming is a sport of speed practiced on the surface or underwater. The purpose of this study was to investigate the difference between two finswimming starts: the grab start (GS) and the research start with hands on metatarsals (HMS). Fourteen well training young male finswimmers participated in our study and assessment the flight, the angle of entry, the angle of knee and the performance at the first 15-m. The results show differences between the two starts in the flight [GS: 130.3±9.1 vs. HMS 136.2±7.9; t(13)=-6.08, p=0.000], in the angle of knee [GS: 107.1±8.9 vs. HMS 115.7±9.9; t(13)=-2.57, p=0.024], in the angle of entry [GS: 55.4±7.4 vs. HMS 52.6±5.2; t(13)=2.71, p=0.018] and at the first 15-m performance [GS: 5.7±0.5 vs. HMS 5.4±0.3; t(13)=4.17, p=0.001). This study demonstrates that the HMS is able to improve the parameters during entry which related with faster swimming.

Differences between the Grab Start and Track Start in Collegiate Swimmers

Differences between the Grab Start and Track Start in Collegiate Swimmers

The biomechanical structure of swim start performance

The aim of this study was to analyse the significance of various biomechanical parameters in swim start performance for the grab and track start techniques. To do so, structural equation models were analysed, incorporating measurements for the take-off phase, flight phase and entry phase. Forty-six elite German swimmers (18 female and 28 male; age: 20.1 ± 4.2 yrs; PB (100 m Freestyle): 53.6 ± 2.9 s) participated in the study. Their swim start performance was examined within a 25-m sprint test. Structural equation modelling was conducted in separate models for the block time, flight time and water time and in a combined model for swim start time. Our main finding was that swim start time is predominantly related to water time and determined to a lesser extent by block time and flight time. We conclude that more emphasis should be given to the water immersion behaviour and the gliding phase when analysing swim start performance. Furthermore, significant differences were found between the grab start and track techniques as regards the biomechanical parameters representing the take-off phase and water phase.

Contribution of hand and foot force to take-off velocity for the kick-start in competitive swimming

ABSTRACTThis study examines the hand and foot reaction force recorded independently while performing the kick-start technique. Eleven male competitive swimmers performed three trials for the kick-start with maximum effort. Three force platforms (main block, backplate and handgrip) were used to measure reaction forces during starting motion. Force impulses from the hands, front foot and rearfoot were calculated via time integration. During the kick-start, the vertical impulse from the front foot was significantly higher than that from the rearfoot and the horizontal impulse from the rearfoot was significantly higher than that from the front foot. The force impulse from the front foot was dominant for generating vertical take-off velocity and the force impulse from the rearfoot was dominant for horizontal take-off velocity. The kick-start’s shorter block time in comparison to prior measurements of the grab start was explained by the development of horizontal reaction force from the hands and the rearfoot at the beginning of the starting motion.

Analysis of angular momentum effect on swimming kick-start performance

The aim of this study was to analyse the mechanics of rotation and the temporal, angular and kinematics variables during the aerial phase for the kick-start with respect to the grab start. Nine elite swimmers (70.0 ± 7.7 kg; 178 ± 9.4 cm; 24.5 ± 5.3 years; 824 ± 119 FINA points scoring) performed the starts on the OMEGA OSB11 starting block followed by 5 m gliding at maximum velocity. Nineteen comparisons of kinematics variables across start technique were performed with critical alpha adjusted using a Holm's correction to maintain an experiment-wise type I error rate of p <0.05. The differences were statistically evaluated by T-test and Wilcoxon test. Significant advantages for the kick-start were observed in all temporal variables (except in the flight time) and in the vertical take-off velocity. Similarities in the centre of mass angular momentum at take-off (120.89 ± 17.66, 126.61 ± 13.51 s-1.10-3, p-value <0.294; kick-start and grab start) caused that KS did not increase the temporal advantages obtained on the block at 5 m distance. Two different rotational movements were found for both techniques. A displacement of the rear leg and front leg on the block and during the flight respectively permits a higher lower limbs position relative to the trunk at hands entry for kick-start. However, larger rotational movement of the trunk characterized grab start. It was concluded that shorter block times and rotational displacements of the lower limbs on the block and flight phase are the key of the best performance for kick-start at 5 m distance.

Effective Swimmer's Action during the Grab Start Technique.

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.

Body composition and kinematic analysis of the grab start in 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.

Biomechanical Influence of Start Technique Preference for Elite Track Starters in Front Crawl

The aim of this study was to analyse the differences between preferential and non preferential start technique, and the inter-trial variability. Seven elite swimmers, who used track start as preferential technique, realised three trials in track and grab start. The kinematical analysis assessed the durations of the block, flight, entry, glide, leg kicking and full swimming phases to the 15-m mark. Aerial (sum of block and flight phase with head mark) and underwater (from entry to the head reach the water surface) phases, number of underwater leg undulations and arm stroke to 15m were also measured. The kinetic analysis assessed reaction and impulse time and total impulses in vertical and horizontal axis. Track start, as preferential technique, had shorter block and entry phases but similar flight phase. In grab start, swimmers spend more time in the impulse and obtained higher vertical impulse values; moreover higher inter-trial variability was found for non-preferential technique suggesting lower efficiency. Differences of kinematics and kinetics observed tended to explain that the preferential technique is highly stabilised and reproducible by the swimmers. However, no differences on the 15m start time performance are observed between the two techniques, confirming the high skill level of the swimmers, and notably their capability to compensate lower block efficiency by effective underwater phases. Indeed, the relative duration of the underwater phases, the number of leg undulations and arm strokes are very similar in both techniques.

Improving Diving Skill through Verbal Feedback and Video Feedback

One of the duties of a physical education instructor is to teach students perform motor skills efficiently and excel in different sports activities. However, students have different abilities in performing complex motor skills and usually result in injuries if the execution is incorrect. Feedback is given to improve one’s performance. This study aimed to identify the effectiveness of verbal feedback and video feedback in the perfor­mance of grab start diving skill. Specifically, it determined if verbal with video feedback is more effective than verbal feedback only in improving motor skill. Forty male students enrolled in swimming class were divided into two groups. After the first performance of two groups, group A was given verbal feedback to improve performance while group B viewed their own video clips and discussions were done. The results concurred that verbal feedback is an effective tool which contributes to the improvement of students’ motor skills. However, it is much effective if verbal feedback is combined with video feedback. Using an appropriate technology in aid of teaching motor skills, the students are prohibited in injuries, able to cope with mistakes efficiently in performing motor skills, and teachers manage to use time efficiently in introducing new motor learning.Keywords: Physical Education, motor skill, video feedback, diving, experimental design, Philippines

A comparative Analytic study of some (kinematics) variables between the Grab start of conventional and track position from above platform to begin of Nineveh governorate team Swimmers

A comparative Analytic study of some (kinematics) variables between the Grab start of conventional and track position from above platform to begin of Nineveh governorate team Swimmers

A Comparison of Two Swimming Start Techniques from the Omega OSB11 Starting Block

Recently the world governing body of aquatic sport has approved the use of a new starting platform (Omega OSB11), and it is currently being used at all international events. Due to the recent approval, swimmers are modifying their start techniques to be able to maximize performance from the new platform. This study investigated the effectiveness of the grab and track competitive swimming start techniques off of the Omega OSB11 start block using a single-subject experimental design. A replica start block was constructed with an embedded force plate. Four subjects participated in this study; two males and two females. The protocol consisted of six starts; three of the track start technique, and three of the grab start technique. Using kinetic data collected from the force plate and signal from an electronic starter, the time to two-meters was predicted. A two-tailed paired t-test was used to determine if the track starts were significantly faster than the grab starts for each subject. Results show that all four subjects were faster to the two-meter mark using the track start technique than the grab start method. Our findings suggest that swimmers should consider using the track start over the grab start on the Omega OSB11 platform.

Influence of Angles of Attack, Frequency and Kick Amplitude on Swimmer’s Horizontal Velocity During Underwater Phase of a Grab Start

The underwater phase of starts represents an important part of the performance in sprint swimming's events. Kinematics variables that swimmers have to take into account to improve their underwater phase of starts are unknown. The aim of this study was to determine the kinematics variables that improve performance during the underwater phase of grab starts. A three-dimensional analysis of the underwater phase of ten swimmers of national level was conducted. Stepwise multiple linear regressions identified the main kinematics variables that influence the horizontal velocity of the swimmer each 0.5 m in the range of 5 to 7.5 m. The results show that the kinematics parameters change during the range of 5 to 7.5 m of the underwater phase of the starts. For this population of swimmers, the results enable proposals of four principles to improve the underwater phase: i) to be streamlined at the beginning of the underwater gliding phase, ii) to start the dolphin kicking after 6 m, iii) to generate propulsive forces using only feet and legs during underwater undulatory swimming, iv) to improve the frequency of underwater undulatory swimming.

Differences in the Efficiency Between the Grab and Track Starts for Both Genders in Greek Young Swimmers

The aim of this study was to determine the differences in the kinematic parameters between the grab and track starts and the differences in these two starts between genders. A total of 27 swimmers at the competitive level participated in the study, 13 boys (mean ± SD: age 15.8 ± 0.8 years, body mass 67.7 ± 7.7 kg and body height 178.6 ± 5.7 cm) and 14 girls (mean ± SD: age 16 ± 0.8 years, body mass 59.2 ± 6.6 kg and body height 166.2 ± 6.7 cm). Each swimmer performed three attempts for both start techniques. The best attempt of the grab start and the track start was taken for further analysis. The following kinematic parameters were analysed: flight distance, flight time, flight velocity, entry angle and reaction time. The males had greater numeric values for the results in all kinematic parameters for the grab start compared with the track start, except for flight velocity and entry angle (flight time 0.42 vs. 0.41 s, flight distance 3.21 vs. 3.14 m, flight velocity 7.76 vs. 7.83 m/s, entry angle 44.22 vs. 43.85 degrees and reaction time 0.86 vs. 0.81 s). The females also had greater numeric values for the results in all kinematic parameters for the grab start compared with the track start, except for flight time (flight time 0.38 vs. 0.38 s, flight distance 2.82 vs. 2.73 m, flight velocity 7.47 vs. 7.31 m/s, entry angle 45.18 vs. 44.79 degrees and reaction time 0.88 vs. 0.82 s). These results indicate that the males had significantly better results for flight time and flight distance compared with the females for the grab start (flight time 0.42 vs. 0.38 s, flight distance 3.21 vs. 2.82 m). In the case of the track start, the males had significantly better results for flight distance (3.14 vs. 2.73 m). Exploring the characteristics of the two starts did not lead to any significant kinematic differences. Therefore, a conclusion that demonstrates the superiority of one of the techniques cannot be reached. The coach, together with each swimmer individually, should devote some time to decide after some tests what type of start is better for the body type and general qualifications of the swimmer.

High-Level Swimmers’ Kinetic Efficiency during the Underwater Phase of a Grab Start

The purpose of the present work was to study swimmers' efficiency during the underwater phase of the grab start. Eight high-level swimmers participated in this study. They performed two types of start: a regular grab start (with underwater leg propulsion after the glide) and a grab start with no underwater movement (swimmers had to remain in a streamlined position). Four cameras filmed the entire underwater phase of all starts. Nine anatomic landmarks were identified on the swimmers' bodies and their positions were calculated using a modified double plan DLT technique. From these positions and Dempster's anthropometric data, the center of mass position and velocity were also determined. Kinetic energies were also calculated. This velocity and kinetic energies for the two types of start were compared. Swimmers began underwater leg propulsion 1.69 m too soon. The global and internal energies were significantly higher for the start with underwater leg propulsion. Nevertheless, swimmers' velocities were equivalent for both starts. These results suggest that the swimmers did not use the underwater phase of the start efficiently: By kicking too soon, they did not succeed in producing higher velocities and thus wasted energy.

Comparison of Grab Start between Elite and Trained Swimmers

This study analysed motor control during front crawl swimming starts by elite and trained swimmers, based on comparisons of: 1) kinematic and kinetic parameters of the start and 2) variability of these parameters across 3 trials per swimmer. Given that the start time to the 15-m mark is greatly influenced by the swimming phase, the study also compared the stroking and coordinative parameters from water entry to 25-m in the 2 skill groups. The swimmers performed 3 x 25-m at the 50-m race-pace and used their preferential start technique (grab start). The elite swimmers showed better start organization as reflected by higher impulse values in the direction of intended displacement despite similar block phase durations. They then spent more time in the water entry, gliding and leg kicking phases, with shorter swimming phase duration and 15-m start time than the trained swimmers (p<0.05). The trained swimmers showed significantly lower values for stroke length and velocity (p<0.05) during the swimming phase. Analysis revealed low intra-subject variability (across the 3 trials) but high inter-subject variability, indicating that both elite and trained swimmers had mastered distinct, though different, motor patterns.

Different Profiles of the Aerial Start Phase in Front Crawl

This study analyzed the kinematics and kinetics (jumping ability) of the aerial start phase in 11 elite front crawl sprinters. The aim was to determine whether a particular start technique leads to a short 15 m start time or whether several start profiles contribute equally well. All swimmers performed 3 starts using their preferential style, which was the grab start for all, followed by a 25-m swim at maximal velocity. Countermovement jump enabled to determine vertical jumping ability. Using a video device, phase durations, angles at takeoff and entry, and hip velocity were assessed. Correlation between all variables and the 15 m start time established the common features of an effective start but also revealed great intersubject variability. Cluster analysis enabled to distinguish 4 start profiles (flat, pike, flight, and Volkov), indicating that several individual profiles lead to short 15 m start times. It could be advised to consider the intersubject variability in relation to start time before favoring unique strategy.

Kinematical Profiling of the Front Crawl Start

This study analysed the start phases of 15 elite front crawl swimmers, all specialists of sprint events. The first aim was to determine which phases were correlated with the 15-m start time. The features common to the sample of swimmers were then established and individual profiles were clustered. The subjects performed two 25-m trials at the 50-m race-pace using their preferential start technique (grab start). The kinematical analysis assessed the durations of the block, flight, entry, glide, leg kicking and full swimming phases to the 15-m mark. Stroking parameters and the index of arm coordination (IdC) were analysed for the swimming part (10-20 m) of the 25-m. Through the swimming part IdC increased while stroke length and velocity decreased (p<0.05). The relative durations of the aerial (block, flight), entry and underwater phases were correlated with start time. Inter-subject variability was observed, which suggests that various motor solutions were used for the start. Notably, four clusters led to a short 15-m start time: the leg kicking style, mixed "leg kicking/swimming" style, long glide style and short glide style.

Analysis of swimmers’ velocity during the underwater gliding motion following grab start

The purpose of this study was to determine the swimmers’ loss of speed during the underwater gliding motion of a grab start. This study also set out to determine the kinematical variables influencing this loss of speed. Eight French national-level swimmers participated in this study. The swimmers were filmed using 4 mini-DV cameras during the entire underwater phase. Using the DLT technique and the Dempster's anthropometric data, swimmer's movement have been identified. Two principal components analysis (PCA) have been used to study the relations between the kinematical variables influencing the loss of speed. The swimmers reached a velocity between 2.2 and 1.9 m s −1 after their centre of mass covered a distance ranging between 5.63 and 6.01 m from the start wall. For this range of velocity, head position was included between 6.02 and 6.51 m. First PCA show that the kinematical parameters at the immersion (first image at which the swimmers’ whole body was under water) are included in the first two components. Second PCA show that the knee, hip and shoulder angles can be included in the same component. The present study identified the optimal instant for initiating underwater leg movements after a grab start. This study also showed that the performance during the underwater gliding motion is determined as much by variables at the immersion as by the swimmer's loss of speed. It also seems that to hold the streamlined position the synergetic action of the knee, the hip and the shoulder is essential.