Ara making a splash in swim cap research

_{Soul cap (left) and the Speedo cap tested by the Ara team}

In a sport where milliseconds count, new findings into the drag of swim caps by researchers at Ara Institute of Canterbury are set to make waves.

An interdisciplinary group of sport science and engineering researchers is using a lab-based wind tunnel to investigate the effectiveness of different swim caps and the impact of how hair is styled within them.

Lead researcher Dr Peter Olsen said their interest began with examining the drag of Soul swim caps designed for long, afro and dreadlock hair after they were controversially banned at the Tokyo Olympics.

“Critics of the ban argued that it was a setback for inclusivity and equity in swimming, affecting minority group participation. While Soul swim caps have since been approved for use by the International Swimming Federation, we wanted to explore the science and answer the question of whether it could confer an advantage over a standard Speedo cap,” Olsen said.

The Ara team— Graeme Harris, Dr Olsen, Dr Nay Lin Oo, Dr Helen Marshall and Dr Lindsey Alton—commenced testing in an open circuit wind tunnel using software to measure the aerodynamic drag of a model while at an angled head position.

Findings just released in the Journal of Sport and Exercise Science (Vol. 8, Issue 2, 21-25 (2024)) found no performance advantage for a range of sizes of the Soul caps as they in fact created more drag than the Speedo cap, with larger Soul caps showing progressively higher drag.

“The increased drag could be due to the uneven surface of Soul caps, which have more wrinkles than the smoother Speedo cap. Since it’s unlikely Soul caps provide any performance advantage over standard caps, the Olympics ban seems unwarranted,” Olsen reported.

Further studies are underway to explore the effect of swim cap shape and surface on drag in the wind tunnel.

A group made up of Ara academics as well as former champion swimmer Anna Simcic (High Performance New Zealand) and Ashleigh Macdonald (Cotswold Mātāhae) has taken a deep dive into how different longhaired hairstyles within a cap can affect drag in the backstroke discipline.

Previous research has focussed on the drag caused by a dome swim cap shape on male swimmers with short hair. The Ara-funded team wanted to explore the impacts of the style of cap and the hairstyle within it for elite female backstroke competitors who typically wear their hair in either a low bun (87.5%) or high bun (12.5%).

They found that a high bun in a swim cap resulted in similar drag to earlier studies (involving males with short hair) while mid and low bun styles increased drag significantly.

However, the authors are advising caution in the interpretation of the findings, as further tests and statistical analysis were needed to determine their validity and reliability.

_{Caps with different hairdos – but do they make a difference?}

A third study arose when one of the researchers watching the Paris 2024 Olympics noticed swimmers using the high-tech Arena Aquaforce swimming cap which has concentric circles at the crown forming an undulating surface.

“Previous research had shown that smooth, rigid silicone swim caps caused less drag than those with seams or dimples, so our team wanted to study the performance of the new high-tech Arena Aquaforce swim cap with a raised circular surface in a lab. We chose to measure it against the smooth surface Arena high-speed 3D cap.”

The Arena Aquaforce cap produced a significant 1.2% decrease in drag compared to the Arena high-speed 3D swim cap in a model head in the backstroke position.

“Given the small winning margins of milliseconds in elite swimming, the Aquaforce cap could offer a slight advantage in competition, but we are looking to undertake further research with computer modelling to validate the wind tunnel findings,” Olsen said.

Olsen said the team was keen to turn its research focus to Paralympian swimmers as there had been minimal study in this area.