Relationships between kinematics and undulatory underwater swimming performance

ABSTRACT

Undulatory underwater swimming (UUS) is one of the major skills contributing to performance in competitive swimming. UUS has two phases– the upbeat is performed by hip extension and knee flexion, and the downbeat is the converse action. The purpose of this study was to determine which kinematic variables of the upbeat and downbeat are associated with prone UUS performance in an elite sample. Ten elite participants were filmed performing three prone 20 m UUS trials. Seven landmarks were manually digitised to calculate eighteen kinematic variables, plus the performance variable– horizontal centre of mass velocity (V_COM). Mean V_COM was significantly correlated with body wave velocity (upbeat r = 0.81, downbeat r = 0.72), vertical toe velocity (upbeat r = 0.71, downbeat r = 0.86), phase duration (upbeat r = −0.79), peak hip angular velocity (upbeat r = 0.73) and mean knee angular velocity (upbeat r = −0.63), all significant at P < 0.05. A multiple stepwise regression model explained 78% of variance in mean V_COM. Peak toe velocity explained 72% of the variance, and mean body wave velocity explained an additional 6%. Elite swimmers should strive for a high peak toe velocity and a fast caudal transfer of momentum to optimise underwater undulatory swimming performance.

KEYWORDS:

• Dolphin kick
• body wave
• phase
• maximum velocity

Acknowledgements

The authors thank Australian Institute of Sport for the Postgraduate Scholarship to complete this work and for the use of the Wetplate system and consumables, Swimming Australia for funding athletes to travel for biomechanical testing and data collection, National Sport Information Centre and University of Sydney for access to published resources, coaches Tracey Menzies, John Fowlie and Scott Talbot for allowing their athletes to participate, Rebecca Pahl for assistance with data collection, Dr. Bruce Mason and Colin Mackintosh for providing information on the intricacies of the Wetplate system, Amy Lewis and John Baker for reviewing this paper.

Disclosure statement

No potential conflict of interest was reported by the authors.