The Characteristics of Underwater Dolphin Kicking in Swimming: A Systematic Review

INTRODUCTION
The quality of technique is a determining factor in swimming performance. Depending on the length of the course and the discipline, the underwater phase accounts for either 30% or 60% of the competition distance [1]. The dolphin kicks are performed during the underwater phase in order to maintain a high speed after the start. The quality of the kicks is critical to overall swimming performance. This study systematically summarises empirical evidence on the characteristics of the underwater dolphin kick.
METHODS
The SURF database of the German Federal Institute of Sport Sciences was used for this purpose. This database combines SPOLIT, SPOFOR, SPOMEDIA, the Directory of Open Access Journals (DOAJ), the International Society of Biomechanics in Sport (ISBS) and PubMed Central (PMC). Six keywords were used in the search (underwater dolphin kick, underwater kick, gliding, undulation, butterfly kick and passive drag). The findings were structured according to the characterisation of motion within the theory of movement by Meinel & Schnabel (2015) [2].
RESULTS
After screening a total of 771 articles, 12 were eligible for analysis according to the inclusion criteria: all studies included e.g. movement amplitude, movement frequency, speed and angle of attack of different body parts to describe the optimal underwater dolphin kick. Two studies investigated the influence of different body positions on the underwater dolphin kick. Nine studies looked at the optimal execution of movements and the most effective angles between the different joints used. One study focused on different net forces during the underwater dolphin kick.
DISCUSSION
Our findings will be discussed according to the following characterisations of movement [2]: (1) movement rhythm (i.e., efficiency and frequency), (2) movement coupling (i.e., muscle activation), (3) flow of movement (i.e., movement progressions), (4) movement constancy (i.e., maintaining movement), (5) range of motion (i.e., amplitude and length) and (6) movement speed (i.e., kicking speed).
REFERENCES
[1] Atkison, R., Dickey, J., Dragunas, A. & Nolte, V. (2014). Importance of sagittal kick symmetry for underwater dolphin kick performance. Human movment science, 33, 298-311, https://doi.org/10.1016/j.humov.2013.08.013
[2] Meinel, K., Schnabel, G., & Krug, J. (2007). Bewegungslehre - Sportmotorik: Abriss einer Theorie der sportlichen Motorik unter pädagogischem Aspekt [Movementtheory- sport motor skills: outline of a theory of sport motor skills from a pedagogical point of view] (11., überarb. und erw. Aufl.). Aachen: Meyer & Meyer.