The Tokyo Olympics had no Soul: A swimming cap controversy

Abstract

The Soul swimming cap that is designed specifically for long hair including afro and dreadlock hair was banned by the swimming body FINA at the 2021 Tokyo Olympics. The ban was due to the possibility that the Soul cap could increase swimming performance. The ban attracted considerable media attention and backlash centred around inclusivity and the low participation of minority groups in swimming. Anecdotally, swimmers suggested a larger cap such as the Soul cap could actually decrease performance, and previous research has found wrinkled swimming caps produced higher drag. There is no research on the drag of the Soul cap, therefore the purpose of this study was to investigate the drag of Soul caps compared to a standard Speedo competition cap. A wind tunnel, set at a speed equivalent to swimming speed, was used to measure the drag on a model head with a long wig (representing a swimmer with long hair) in different swimming cap conditions (Soul swimming caps designed for long hair (small (S-Soul), large (L-Soul), extra-large (XL-Soul)) and a Speedo cap). The Speedo cap produced significantly less (p < 0.0001) drag compared to all Soul caps (mean ± SD - Speedo:141.54 ± 2.92 g vs. 150.53 ± 4.83 g (S-Soul,), 164.54 ± 3.24 g (L-Soul) and 172.87 ± 3.70 (XL-Soul)). Differences in drag were progressively larger with a statistically significant increase with a larger size of Soul swimming caps (8.89 g to 31.33 g, p < 0.0001). It is likely the differences in cap conditions were due to wrinkles, with less wrinkling occurring in Speedo and increased wrinkling in the larger Soul swimming caps. Our findings indicate it is unlikely that a Soul cap would confer a performance advantage relative to a standard Speedo cap. Future research could investigate if our results are substantiated in aquatic conditions..