Gonjo, T., Ichikawa, H., Tsubakimoto, S., & Takagi, H. (2010). A comparison of characteristics of high functional swimwear for competitive swimming. A paper presented at the XIth International Symposium for Biomechanics and Medicine in Swimming, Oslo, June 16–19, 2010.

This study clarified factors of the highly functional swimwears that made such an impact in 2007-2009. Two elite swimmers performed in a LZR Racer (L), Aqua Force (F), and X-Glide (X), as the highly functional swimwears, and Aile-Bleue (B) as a comparative swimwear. The LZR had high wearing pressure, the Aqua Force was made of rubber, and the X-Glide had both features of the LZR and the Aqua Force. Performance characteristics measured were: 1) underwater velocity after starting, 2) the cross sectional area of a leg, and 3) passive drag in a swimming treadmill.

Post-start velocity (m/s) was highest in the X-Glide although the differences were not significant (X:2.1±0.5, L:2.0±0.4, F:2.0±0.4, B:1.9±0.5). The LZR constricted the thigh cross-sectional area more than the others (X:149.3±16.1, L:147.4±19.4, B:152.7±18.8). Passive drag was largest with the LZR. Passive drag (N) with the X-Glide and Aqua Force were small at lower velocities but became larger at higher velocities (velocity 0.6-1.4 m/s - X:10.2±10.4, L:14.7±11.8, F:6.5±10.3, B:10.0±12.2; velocity 1.6-1.8m/s - X:62.5±18.3, L:63.5±14.1, F:49.3±13.1, B:45.0±10.9). The X-Glide and Aqua Force suits also induced the trailing leg positions to be more horizontal than the other two suits.

The passive drag results revealed that rubber swimwears (X-Glide and Aqua Force) indicated a different tendency between the lower and higher flow velocity. It was thought that the drag decreased due to the body position becoming closer to the horizontal because the rubber swimwears tended to lift the legs. However, that effect induced an increase in wave drag at higher velocities, causing the passive drag results to reverse between the rubber swimwears and others. For an effect of constriction by the swimwears, it was observed the cross-sectional area of the thigh was decreased by wearing the LZR and X-Glide.

Implication. The major effects of the now-banned swimsuits were: The Aqua Force reduced drag by lifting the legs; The LZR's restriction restrained leg vibrations; and the X-Glide showed both benefits. [Rubber no longer can be used on swimsuits.]

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