Effect of fastskin suits on performance

Páginas: 8 (1894 palabras) Publicado: 10 de enero de 2010
Effect of Fastskin Suits on Performance, Drag,and Energy Cost of Swimming

Laboratory of Clinical and Exercise Physiology, Medical Faculty, Jean Monnet University of Saint-E´ tienne, FRANCE; Aspire Academy for Sports Excellence, Doha, QATAR; 3School of Physical Education, University of Otago, Dunedin, NEW ZEALAND; and National Sports Institute Malaysia,Kuala Lumpur, MALAYSIA.

Since the Sydney Olympics games, swimmers have been allowed to wear drag-reducing suits in competition. Two examples of this are the new fastskin suits of Lycra or elastane covering either a part or the whole body. Two different technologies are used, either woven fabric (Arena type) or knitted fabric (Speedo type). It has been indicated that they reduce friction andpressure drags. Mollendorf et al. showed that fastskin suits decreased hydrodynamic resistances by 3% to 10%. This reduction was proportional to the covered surface of the skin. These data were confirmed by Benjanuvatra et al.
The reduction in passive drag is assumed to be beneficial for swimmers, possibly resulting in higher swimming velocity for the same energy cost as well as reducing the energycost for swimming at a given velocity. However, this hypothesis remains to be demonstrated. Indeed, Roberts et al. Showed that wearing an earlier version of a full-body suit (FB) at a given velocity did not decrease the oxygen uptake. These authors did not find any change in the hydrodynamic resistances either. These results were confirmed by Toussaint et al. measuring active drag.
Until thepresent, no study has measured the maximal performance benefit when wearing the new-generation fastskin suit. The drag and the energy uptake have been measured during submaximal swimming, but the early results are controversial.
Thus, the aim of this study was to compare the effects of the two most used fastskin suits: one covering almost the full body, sleeveless, from shoulder to ankle, the other onecovering the whole legs (L), from waist to ankle. The effects on 25- to 800-m performances were measured in real swimming situation, that is, in a pool, in 14 competitive swimmers, whereas drag and energy cost of swimming were measured in a flume at submaximal velocities to achieve comparisons at exactly the same velocity in the three conditions. The hypothesis was that fastskin suits shouldimprove performance at competition speed (i.e., 1.5–2.3 mIsj1) and decrease drag and energy cost in proportion to the body skin coverage.

Subjects. Fourteen competitive swimmers signed informed consent and participated in the studies on a voluntary basis: 4 females (19+-3 yr, 169+-5 cm, 67+-6 kg) and 10 males, 11 young swimmers (18+-3 yr, 176+-8 cm, 72+-8 kg) and 3 master swimmers (52+-2yr, 172+-6 cm, 78+-4 kg). Their best 100-m performances of the year were 62.8+-0.4, 57.6+-3.5, and 61.3+-5.3 s, respectively. They swam on average once or twice a day for a total distance of 20 to 40 kmIwkj1. Approval for the project was obtained from the University of Otago Committee on Human Research.
Swim performance. Swimmers swam at maximal effort in a 25-m pool, over 2 wk, for six distancesof 25, 50, 100, 200, 400, and 800 m freestyle when wearing FB, L, and a normal racing suit (N). The total number of swims was 252, corresponding to 6 distances _ 3 swimming conditions _ 14 swimmers. This number is relevant because it covers almost all short and long distances performed in competition. The order of all suit and performance conditions were randomly assigned. One day they swam, in thesame session and after a standardized warm-up, 25, 50, and 100 m with rest between swims of 5 and 10 min. The swims were performed from a push-off in water rather than a start and were timed from when the feet broke contact with the starting wall to when the hand touched the finishing wall. The push-off start was used to avoid any diving effect on average velocity. After 2 or 4 d of recovery,...
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