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TRANSCRIPT
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The importance of sagittal kick symmetry for underwater dolphin kick performance
Atkison, R.1,2., Nolte, V.1, Dickey, J.1 & Dragunas A.1 1The University of Western Ontario, London, ON
2Canadian Sport Institute Ontario, Toronto, ON
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Basic Mechanics
• Cyclic motion – Up-peak – Down-peak
• 2 Distinct Phases – Downkick (DK) – Upkick (UK)
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Rationale
• Experienced swimmers shed large vortices during DK & smaller vortices in UK phases; inexperienced swimmers shed small vortices during DK phase and none during UK (Arellano, 1999; Arellano et al., 2000)
• Dolphins/cetaceans perform symmetrical DK & UK phases (Ungerechts, 1983; Von Loebbecke et al., 2009a; Von Loebbecke et al., 2009b)
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Purpose
To evaluate the kinematics of DK and UK phases and how symmetry between DK and UK is related to performance
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• 15 male swimmers from University and Club Age = 21.5±3.2 yrs,
Experience = 11.4 ± 5.6 yrs
• Filmed 3 trials of 15m UDK at max effort
• Digitized 12 landmarks
Methods
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Measured & Calculated: • vertical joint amplitudes & velocities, • horizontal CM displacements & velocities, • joint angles, & kicking frequencies Each variable determined for whole kick cycle, DK & UK Symmetry ratios determined for each variable (DK/UK) Correlated mean horizontal velocity (Vx) with all DK & UK values, and with symmetry ratios
Methods
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Results
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Fastest: Vx = 1.84m/s
Median: Vx = 1.67 m/s Slowest: Vx = 1.30 m/s
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Additional Findings
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Limitations
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Conclusions
• Kick symmetry highly related to UDK performance – Those who perform UK well tend to be faster at
UDK
• Factors contributing to UK performance…
– Peak vertical toe velocity – Hyperextended knees and ankles at start of UK, less
knee flexion at end of UK
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Further Study
• Low hand amplitudes related to performance – Importance of thoracic mobility – Drag reduction?
• Bilateral asymmetries
• Evidence of trunk undulation
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Acknowledgments
Canadian Sport Institute Ontario UWO Swimming
London Aquatic Club Dr. Volker Nolte Dr. Jim Dickey
Dr. Horia Hangan Coach Paul Midgley Andrew Dragunas
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Works Cited
Arellano, R. (1999). Vortices and propulsion. In R. Sanders & J. Linsten (Eds.), Applied proceedings of the XVII international symposium on biomechanics in sports: Swimming (pp. 53-65). Perth: Edith Cowan University.
Arellano, R., Pardillo, S., & Gavilán, A. (2000). Underwater undulatory swimming: kinematic characteristics, vortex generation and application during the start, turn and swimming strokes. Coaches' Infoservice [On-line]. Available: http://www.coachesinfo.com/index.php?option=com_docman&task=cat_view&gid=36&Itemid=68
Ungerechts, B. (1983). A comparison of the movements of the rear parts of dolphins and butterfly swimmers. Biomechanics and Medicine in Swimming, 215-221.
Von Loebbecke, A., Mittal, R., Fish, F., & Mark, R. (2009a). Propulsive Efficiency of the Underwater Dolphin Kick in Humans. Journal of Biomechanical Engineering, 131, 054504.
Von Loebbecke, A., Mittal, R., Fish, F., & Mark, R. (2009b). A comparison of the kinematics of the dolphin kick in humans and cetaceans. Human Movement Science, 28(1), 99-112. Elsevier B.V. doi:10.1016/j.humov.2008.07.005
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The importance of sagittal kick symmetry for underwater dolphin kick performance Basic MechanicsRationalePurposeMethodsMethodsResultsSlide Number 8Slide Number 9Additional FindingsSlide Number 11Slide Number 12LimitationsConclusionsFurther StudyAcknowledgmentsWorks Cited