Ross Sanders Centre for Aquatics Research and Education Physical Education Sport and Leisure Studies The University of Edinburgh

Methods Applied at CARE  3D analysis methods  Accurate WBCM calculation  Energy, angular momentum, net torques  Quantifying rhythm - Fourier analysis

3D Analysis Methods

Maximising Accuracy - Calibration Psycharakis, S.G, Sanders, R.H., and Mill, F. (2005). A calibration frame for 3D analysis of swimming. In Q. Wang (Ed.) Proceedings of XXIII International Symposium on Biomechanics in Sports, The China Institute of Sports Science, Beijing, pp

Maximising Accuracy - Anthropometric Data - Elliptical Zone Method Jensen, R.K. (1978). Estimation of the biomechanical properties of three body types using a photogrammetric method. Journal of Biomechanics, 11,

Deffeyes, J, and Sanders, R. (2005). Elliptical zone body segment modeling software: Digitising, modeling and body segment parameter calculation. In Q. Wang (Ed.) Proceedings of XXIII International Symposium on Biomechanics in Sports, pp

Measuring Rhythm Fourier Analysis:   Any time series data can be represented as a series of waveforms   Each waveform (harmonic) is an integer multiple of the fundamental frequency e.g. 1hz, 2hz, 3hz etc.   Fourier analysis determines the amplitude of each waveform   Fourier analysis determines the ‘phase’ i.e. the timing of when the peaks of the wave are attained

The Possibility of Energy Transmission by Travelling Waves How the Rhythms in Butterfly Influence Performance  WBCM potential energy contributes to energy of the trunk and lower limbs.  Pendulum action changes potential energy to rotational energy of the trunk and lower limbs.  Transmission of energy from thighs to shanks in a body wave.

 Strong propulsion from the kick  Time of maximum force does not coincide with maximum vertical foot speed Effect of the Kick on Propulsion

Why should the two kicks be different in amplitude ? Effect of Wave Phase on Performance

 The phase of H1 relative to H2 produces a strong upbeat and strong downbeat  Adds rotational energy to the trunk  Energy transfer and economy Effect of the Wave Phase on Performance (cont.)

Rhythms in Front Crawl  3D data 200m front crawl. N=7 * 4  'Torsional' wave rather than 'rocking' wave investigated

Wave Velocity of the Harmonics Shoulder-Hip Hip-Knee Knee-Ankle H H H H1 WSSD H2 WSSD H3 WSSD H1 BSSD H2 BSSD H3 BSSD The H3 wave moves from hip to ankle in a consistent manner !

Knee-Ankle H3 Wave Velocity

How the Rhythms in Front Crawl Influence Performance  Arm pull produces high energy of translation Concurrently other arm increases potential energy  No evidence of 'free of charge' energy transmission from trunk to lower body  No evidence of 'free of charge' energy transmission from thighs to shanks The Possibility of Energy Transmission

 Acceleration is dominated by the effect of the two arms pulls  Propulsion is also influenced by the kick Propulsion in 6 Beat Front Crawl

Conclusions:  Three-dimensional analysis techniques to quantify kinematics, kinetics, and three dimensional waveforms can provide new insights into how performance is optimised in swimming.

 The roll angular momentum reflects the strong H3 rhythm possessed by the lower body  The roll angular momentum also reflects the H1 rhythm of the upper body  The rotation of the body is the result of the interaction of the torques from the hydrodynamic forces in reaction to the kick/arm actions, and the torque from the buoyancy force How the Rolling Rhythms are Produced Yanai, T. (2004). Buoyancy is the primary source of generating body roll in front crawl swimming. Journal of Biomechanics, 37,