RESEARCH ARTICLE


Using Wavelet Transform for Speed Fluctuation Analysis During Manikin Carry with Fins



Susana Soares1, 2, *, A. Toubekis3, L.M. Machado1, 2, J.P Vilas-Boas1, 2, R.J. Fernandes1, 2, J.A. Abraldes1, 4
1 Center of Research, Education, Innovation and Intervention in Sport, Faculty of Sport, University of Porto, Porto, Portugal
2 Porto Biomechanics Laboratory, University of Porto, Porto, Portugal
3 Division of Aquatic Sports, School of Physical Education and Sport Science, National and Kapodistrian University of Athens, 17237, Athens, Greece
4 Department of Physical Activity and Sport, Faculty of Sports Sciences, University of Murcia, Murcia, Spain


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© 2017 Soares et al.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: https://creativecommons.org/licenses/by/4.0/legalcode. This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Center of Research, Education, Innovation and Intervention in Sport, Faculty of Sport, University of Porto, Porto, Portugal; Tel: +351220425274; Fax: +351225500687; E-mail: Susana@fade.up.pt


Abstract

Background

Wavelet analysis has been used to locate speed variation changes in swimmers, but this elaborated technique was not so far tested in lifesavers carrying a manikin and using one upper limb and fins for propulsion.

Objective:

Our purpose was to examine the feasibility of using the wavelet analysis to locate time-points of speed variation changes in a manikin carry lifesaving race using stiff and fiber fins.

Method:

Fourteen male lifesavers with a mean age of 20.79±4.93 years performed two 25 m all-out manikin carry swimming races using one upper limb and stiff or fiber fins for propulsion. Speed was recorded with a speedometer and its variation was analysed using a wavelet transform analysis. Video recordings were used to measure stroke rate and stroke length within each race.

Results:

Wavelet analysis detected, for some lifesavers, one (stiff: 10.50±1.29 vs. fiber: 9.75±0.50 s; p>0.05) and, for other lifesavers, two time-points (stiff: 6.75±0.96 and 11.50±1.29; fiber: 7.00±1.41 and 12.00±1.83 s; p>0.05) of speed variation changes. Mean speed was no different with fin types (stiff: 1.38±0.06 vs. fiber: 1.42±0.09 m∙s-1; p>0.05), as well as average, maximum and minimum speed. Stroke rate, stroke length and stroke index did not change within each race.

Conclusion:

Wavelet analysis was effective in detecting one and two time-points of speed variation changes within a short duration manikin carry race independently of the type of fins used. Fiber and stiff fins showed similar biomechanical and speed variations within race changes.

Keywords: Fatigue, Fin type, Lifesaving, Speed variation, Sprint, Wavelet transform.