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
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.
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.
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.
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.
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.
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* 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