University of Kassel Swim Start Research

Transcription

1 University of Kassel Swim Start Research Sebastian Fischer & Armin Kibele Institute for Sports and Sport Science, University of Kassel, Germany

2 Research Fields: Swim Start research I. Materials and Equipment II. Individual Starts 1. take-off cues for training 2. flat vs. pike dives 3. OSB9 vs. OSB11 starts 4. entry strategies 5. stance position 6. swim start modelling III. Relay Starts 1. take-off strategy in relay start 2. step-starts 3. relay race analysis 4. perceptual training IV. Future Projects Conclusions for swimmers and coaches

3 Materials and Equipment Portable Equipment portable starting block with force measurement system above water video cameras (take-off phase) under water video camera (dive-in phase) Relay Starts take-off plate and contact mat with electronic timer

4 1. Take-Off Cues - (Kibele et al. 2007) OSB9 starting block model track start vs. grab start Advantages:...short block times in track start Results of a study on grab start performance (N=14): vs. high horizontal take-off velocities in grab start - horizontal peak force, block time and angular momentum best predictors of grab start performance: 70% explained variance by horizontal peak force - horizontal peak forced used as feedback information for swimmers

5 2. How to Dive? Flat vs. Pike a learning study (Fischer & Kibele, 2010) Study Design: - 10 elite swimmers (flat dive and pike dive groups) - 4 learning blocks with 4 starts - feedback on entry angle + video display - swim start performance: time to 7.5m - flat entry: entry angle < 35 - pike entry: entry angle > 40 Results: - flat and pike divers improved their starting performance significantly - for the take-off angle, in the entry angle, and in the horizontal take-off velocity main effects were found for the time factor and the dive type factor - flat entry improved horizontal take-off velocity - no significant increase in horizontal take-off velocity for the pike entry - opposite effect was true for the pike entry group

6 3. Advantages in the OSB11 vs. OSB9 starting block (Biel, Fischer & Kibele, 2010) 7 elite swimmers: 4 track starters, 4 grab starters Clear advantages for track start on new OSB11 starting block 74 cm vs. 50 cm Length 9 vs. 5 Inclination swim start 7,5m block time v-take-off hor OSB9 Track Start 2,63 s 0,78 s 4,52 m/s } ** } ** } * OSB11 Track Start 2,43 s 0,74 s 4,71 m/s OSB 11 Grab Start 2,54 s 0,82 s 4,54 m/s

7 3. Advantages in the OSB11 vs. OSB9 starting block (Biel, Fischer & Kibele, 2010) 7 elite swimmers: 4 track starters, 4 grab starters Clear advantages for track start on new OSB11 starting block 74 cm vs. 50 cm Length 9 vs. 5 Inclination swim start 7,5m block time v-take-off hor OSB9 Track Start 2,63 s 0,78 s 4,52 m/s OSB11 Track Start 2,43 s 0,74 s 4,71 m/s } * } ** } * OSB 11 Grab Start 2,54 s 0,82 s 4,54 m/s

8 4. Entry Strategies (Fischer, 2013; Fischer & Kibele, 2014) Start performance (time between start signal and head 5m, 6.07, 7.5m, 9m, 9.5m, 10m, 15m) Guimaraes & Hay (1985) Block time Flight time Water time Maglischo (2003) Block time Flight time Entry Glide Emersion Kazumasa et al. (2008) Block phase Flight phase Entry phase Glide phase Stroke phase Vantorre et al. (2010) Seiffert et al. (2010) Block Phase Block Phase Flight Phase Flight Phase Entry Phase Entry Phase Glide Phase Glide Phase Leg Kicking Phase Leg Kicking Phase

9 4. Entry Strategies (Fischer, 2013; Fischer & Kibele, 2014) Algorithm for the determination of body segment coordinates with blurred visual conditions: Because of the limited visibilty the algorithm does not determine the body segments by their end points, as usual, but by their midlines through a simple regression technique.

10 4. Entry Strategies (Fischer, 2013; Fischer & Kibele, 2014) Subjects (N=46) among the best German swimmers within approx. 7% difference to world record, 6 olympic participants, 2 world record holders, 6 European record holder male swimmers (n=28) FINA-Points: ± 63.73, age: ± 3.58 y, height: 1.88 ± 0.05 m, weight: ± 8.90 kg female swimmers (n=18) FINA-Points: ± 57.67, age: ± 4.58 height: 1.76 ± 0.05 m,weight: ± 5.61 kg

11 4. Entry Strategies (Fischer, 2013; Fischer & Kibele, 2014) Statistics: Principal Component Analysis (Varimax with Kaiser Normalization) Cluster analysis (Ward-Method) Two-factorial Anova (Cluster & Gender) 24 Entry Variables 7 Factors 3 Cluster Solutions

12 4. Entry Strategies (Fischer, 2013; Fischer & Kibele, 2014) Cluster analysis for the charaterization of the dynamics of the entry phase 1. Cluster = flat dive (n=15, women=9, male=6) 2. Cluster = pike dive with a quick deflection movement (n=15, women =6, male=9) 3. Cluster = pike dive with a delayed deflection movement (n=16, women =3, male=13)

13 4. Entry Strategies (Fischer, 2013; Fischer & Kibele, 2014) Table: By means of an two-factorial ANOVA were group differences (cluster, gender) detected factor Significant differences between the clusters; p-value Significant differences between the gender; p-value Interaction of the cluster and the gender; p-value body position at the first water contact [***] n.s. n.s. deflection behavior during the entry phase n.s. n.s. duration of the entry phase n.s [***] n.s. horizontal velocity during the entry phase n.s [**] n.s. depth of the dive [*] n.s. n.s. water displacement during the entry phase [***] n.s. n.s. effectiveness of the leg kick n.s. n.s. Speed decrease n.s n.s n.s

14 4. Entry Strategies (Fischer, 2013; Fischer & Kibele, 2014) Steffen Deibler World Record Holder 50m Butterfly Ian Thorpe Entry with Dolphin Kick Important Movement Feature: Hip Angle between first water contact and water immersion of the hip joint

15 4. Entry Strategies (Fischer, 2013; Fischer & Kibele, 2014) Possible meaning of angular momentum about transverse body axis Flat trajectory: Pro: small reduction in horizontal velocity Cons: loss of kinectic energy due to large amounts of displaced water

16 4. Entry Strategies (Fischer, 2013; Fischer & Kibele, 2014) Possible meaning of angular momentum about transverse body axis Flat trajectory: Pro: small reduction in horizontal velocity Cons: loss of kinectic energy due to large amounts of displaced water

17 4. Entry Strategies (Fischer, 2013; Fischer & Kibele, 2014) Possible meaning of angular momentum about transverse body axis Flat trajectory: Pro: small reduction in horizontal velocity Cons: loss of kinectic energy due to large amounts of displaced water

18 4. Entry Strategies (Fischer, 2013; Fischer & Kibele, 2014) Possible meaning of angular momentum about transverse body axis Flat trajectory: Pro: small reduction in horizontal velocity Cons: loss of kinectic energy due to large amounts of displaced water

19 4. Entry Strategies (Fischer, 2013; Fischer & Kibele, 2014) Possible meaning of angular momentum about transverse body axis Flat trajectory: Pro: small reduction in horizontal velocity Cons: loss of kinectic energy due to large amounts of displaced water

20 4. Entry Strategies (Fischer, 2013; Fischer & Kibele, 2014) Possible meaning of angular momentum about transverse body axis Flat trajectory: Pro: small reduction in horizontal velocity Cons: loss of kinectic energy due to large amounts of displaced water

21 5. Optimizing Stance Position Which on the Stance OSB11 (Kibele, Biel & Fischer, 2015) Position? Slawson et al. (2013) : Male and Female Elite Swimmers (N = 32) Input variables: foot rest positions 3 to 5, narrow and wide stance, front leg Results: male swimmers: shorter block times, larger take-off velocities, larger horizontal and vertical peak forces (foot rest) for the narrow stance with a tandem foot position; female swimmers: larger flight distances, smaller vertical take-off forces in narrow stance Barlow et al. (2014) : Male and Female Developmental Level Swimmers (N = 10) Input variables: front-, neutral and rear-weight stance for preferred foot rest position Results: neutral and rear-weighted stance produced faster times to 15 m; rear-weighted stance produced shortest times to 5m; front-weighted stance produced shortest block times,

22 5. Optimizing Stance Position on the OSB11 (Kibele, Biel & Fischer, 2015) Stance Variations relative to Leg Length Narrow and wide stance CM high vs. low CM front- and rear-weighted Front leg: preferred vs. non-preferred 8 stance positions CM height CM position between the feet toe tip distance

23 5. Optimizing Stance Position on the OSB11 (Kibele, Biel & Fischer, 2015) Are individually preferred stance positions best for swim start performance? Which stance posture? CM height? Changes in CM height produce changes in block time (Hay & Guimaraes, 1983; Fischer, 2013) Study Objective: - Analysis of preferred stance positions and - Evaluation of systematic variations of preferred stance positions Reference for variations: Pilot study (experiment 1 in Kibele et al. 2013) 7 female elite swimmers (22 4y; 1,78 0,06m, 65,2 5,4kg); 6 male elite swimmers (24 2y; 1,90 0,03m, 85,8 5,4kg) Means & SDs of CM height and distance from the front end of the block and stance width expressed relative to the individual leg lengths for male and female swimmers separately Example: CM height (above front end of the block) relative to the individual leg length: 0,72 0,04 for females and 0,73 0,04 for male swimmers.

24 5. Optimizing Stance Position on the OSB11 (Kibele, Biel & Fischer, 2015) 3-cluster solution elbow trunkupper arm knee front leg trunkthigh rear trunkthigh front N=3 (0 fem, 3 male) 154 ± 3,4 93 ± 1,5 134 ± 7,6 45 ± 1,0 24 ± 4,3 N=8 (3 fem, 5 male) 169 ± 3,0 98 ± 7,3 123 ± 4,6 45 ± 7,1 21 ± 4,5 N=6 (2 fem, 4 male) 151± 5,0 86 ± 5,3 117 ± 7,7 39 ± 5,6 17 ± 2,3 Oneway F-value 42,9** 6,07* 6,98** n.s. 3,48* post-hoc LSD 1-2** 2-3** 2-3** 1-2* 1-3** 1-3** Oneway : * p < 0,05, ** p < 0,01 cluster 1 (N=3) : elevated CM height, large step size, rear-weighted CM position cluster 2 (N=8) : intermediate CM height, large step size, front-weighted CM position cluster 3 (N=6) : low CM height, small step size, intermediate CM position

25 vertical coordinate (m) CM-height 1 standard deviation 1 standard deviation CM-length step-length horizontal coordinate (m)

26 5. Optimizing Stance Position on the OSB11 (Kibele, Biel & Fischer, 2015) 1 = CM high-front narrow stance 2 = CM high-back wide stance, 3 = CM low-front wide stance 4 = CM low-back wide stance repeated measures variables stance factor stance differences block time 32,2** : 0,92 1-2**, 1-4**, 2-3**, 3-4** swim start time at 5m 7,9* : 0,80 1-4**, 2-3*, 2-4*, 3-4** horizontal take-off velocity 6,1* : 0,70 2-3*, 3-4** horizontal peak force 11,6** : 0,81 1-2**, 1-4**, 2-3*, 2-4*, 3-4** take-off angle 6,5* : 0,71 2-3**, 3-4** shortest block times for the front-weighted CM positions 1 and 3 no differences were observed between the preferred and non-preferred leg except for the high-front narrow stance (No. 1) with superior values for the non-preferred leg. significant interaction effect between the front leg factor and the stance factor (F=5,2*; eta2 = 0,66) best swim start times to 5m in for the front-weighted CM positions 1 and 3 as well no differences between the preferred and non-preferred leg (exception: for the high CM positions 1 and 2 best values for the non-preferred leg) largest horizontal take-off velocities in the back CM positions 2 and 4 for the front-high CM position 1 with narrow stance width a merely slightly smaller take-off velocity in the non-preferred leg largest horizontal peak forces for front CM positions 1 and 3

27 5. Optimizing Stance Position on the OSB11 (Kibele, Biel & Fischer, 2015) mean improvements in swim start time: 0,06s, maximal improvement in swim start time: 0,14s!! 9 of the 17 subjects showed swim start improvements for the stance alternatives better than the preferred stance position. preferred leg in front non-preferred leg in front 1 = CM high-front narrow stance - 2 = CM high-back wide stance - 3 = CM low-front wide stance - 4 = CM low-back wide stance block time (s) swim start time 5m (s) horizontal take-off velocity (m/s)

28 6. Biomechanical Model of the Swim Start (Fischer & Kibele, 2014; Fischer, 2013) What s more important? Flight Phase Take-off Deflection Phase Entry

29 6. Biomechanical Model of the Swim Start (Fischer & Kibele, 2014; Fischer, 2013) Structural Equation Modelling with SPSS AMOS Predictor Variables and Path Coefficients for the Block Time in the Grab Start (left) and in the Track Start (right) based on the deterministic components of the swim start performance published by Guimaraes & Hay (1985)

30 6. Biomechanical Model of the Swim Start (Fischer & Kibele, 2014; Fischer, 2013) Structural Equation Modelling with SPSS AMOS Predictor Variables and Path Coefficients for the Swim Start Time in the Grab Start (left) and in the Track Start (right) based on the deterministic components of the swim start performance published by Guimaraes & Hay (1985)

31 Swim Start Relay Events 1. Take-off strategy in relay start (Kibele & Fischer, 2009) minimizing change-over time or maximizing take-off power (.traditional focus) A learning study with the German junior national teams (N = 26) prior to the European Junior Championships 2009 Training with 2 interventions on two consecutive days: 3 relay starts with video analysis on each day Women relay team freestyle 2009 Gold medal with European Record Men relay team freestyle 2009 Bronce Medal race time swim start performance individual race water phases = times between toe-off and wall contact Change-over phases = times between wall contact (incomming) and toe-off (outgoing)

32 Swim Start Relay Events 1. Take-off strategy in relay start (Kibele & Fischer, 2009) Results: pre-post differences HF-FB = horizontal peak force feedback CT-FB = change-over time feedback relay start time = time between wall contact (incoming) and 7,5m (outgoing) HF CT relay start time males HF-FB (N=7) N ** (+ 12 %) - 0,20 s ** (- 64 %) - 0,17 s ** (- 8 %) CT-FB (N=6) - 48 N ** (- 4 %) - 0,14 s ** (- 50 %) - 0,05 s (- 2 %) females HF-FB (N=6) + 90 N (+ 13 %) - 0,12 s * (- 46 %) - 0,22 s ** (- 9 %)! CT-FB (N=7) + 24 N (+ 3 %) - 0,12 s ** (- 47 %) - 0,12 s * (- 5 %) main effect: group F = 14,0 ** main effect: gender n.s. n.s. F = 4,0 * F = 4,4 * n.s.

33 Swim Start Relay Events 2. Step-start strategy in relay swimming (Kibele & Fischer, 2009) Traditional Swim Start Strategies Individual races: track start Relay races: arm swing start with parallel foot placement

34 Swim Start Relay Events 2. Step-start strategy in relay swimming (Kibele & Fischer, 2009) subjects: 16 elite swimmers short term intervention (1 day with 4 relay starts) arm swing start vs. step-start - time between wall contact and 7,5m Feedback: peak force, change-over time, video display Results: significant improvement of change-over time in both groups tendency for horizontal peak force improvements in both groups no main effect for training in the relay start time but interaction effect (F = 4,3; p = 0,06) tendency for relay start improvements in single-step group (F = 4,3; p = 0,06) decreases in relay start for arm swing group

35 Swim Start Relay Events 3. Race analysis: step starts (Fischer & Kibele, 2014) Race times of the relay finals in the 2010 European Championships and the 2011 World Championships Subjects: all swimmers (88 female and 98 male) of the relay finals who also reached at least the semi finals in the corresponding individual race Parameters: race times, block times, and change-over times of the relay finals and the individual races given by Omega Timing ( time adjustments were made to compare swimming times in both events: -swimming time - change-over time = ST-relay -swimming time - block time was subtracted = ST-individual Efficiency of relay start = ST-individual ST-relay (positive values indicate an advantage of the relay start) Results: - highly significant difference for the efficiency of the relay start in the 4x100F relay races (freestyle and medley) between the first starter ( t 0-50m = -0,03s ± 0,36s, n=18) and the following starters ( t 0-50m = -0,23s ± 0,34s, n=58) - no differences were found for the second part of the races ( t m). No gender effects were detected. Results show that step-start techniques are beneficial for the relay race in comparison with an individual race

36 Swim Start Relay Events 4. Perceptual training in relay start (Biel, Fischer & Kibele, 2010) Call Room Warm-Up for Relay Races Research Issue: Is it possible to improve the receptor anticipation of the approach point in time through a smart phone display prior to a race?

37 Swim Start Relay Events 4. Perceptual training in relay start (Biel, Fischer & Kibele, 2010) Call Room Warm-Up for Relay Races Research Issue: Is it possible to improve the receptor anticipation of the approach point in time through a smart phone display prior to a race?

38 Swim Start Relay Events 4. Perceptual training in relay start (Biel, Fischer & Kibele, 2010) pilot studie: 10 sport science students advanced swimming University of Kassel computerized reaction time experiment regarding the receptor anticipation of the approaching swimmer experiment 1 : temporal occlusion Task: anticipate the wall contact by key press, videos of 6 different swimmers, 4 occlusion conditions: 0%, 25%, 50% and 75% of the time for the last two arm strokes prior to the wall contact 3 blocks with 24 videos in randomized order without feedback results: - no main effect for occulsion - main effect for learning block (F=6,67; p=0,03) - learning effect - Interaction effect: occlusion and block (F=5,24; p=0,033) better anticipation through learning

39 Swim Start Future Projects A. Perceptual-motor training in relay start Parameters: - reaction time - force amplitude video display Pressure Plate Messdruckplatte

40 Swim Start Future Projects B. Parametrization of Water Displacement amount of displaced water indicates loss of kinetic energy

41 Swim Start Future Projects C. Angular Impulse during Swim Start transverse body axis Michael Phelps Rear leg movement in track start produces angular impulse clockwise

42 Swim Start Future Projects C. Angular Impulse during Swim Start longitudinal body axis Michael Phelps Rear leg movement in track start produces angular impulse counterclockwise

43 Swim Start Future Projects D. Handle Placement on the Block Cooperation with Omega Timing Comparative Study: Which handle form and orientation provides best swim start performance?

44 Swim Start Future Projects E. Foot Placement on the OSB11 - Motor Testing for Swimmers How to find the front leg? Power or Strength? Leg-Press Left-Right-Hop

45 Swim Start Future Projects F. Relay Starts on the OSB11 Cooperation with Omega Timing Starting blocks displayed in this image from Beijing 2008 Removal of Foot Plate for Relay Starts?

46 Swim Start Future Projects G. Instability Strength Training for Swimmers Purpose: specific strengthening of the stabilizing muscles

47 Thank you very much for your attention! Armin Kibele Institute for Sports and Sport Science, University of Kassel, Germany