In this blog post, we’ll examine the hydrodynamic principles behind the high-tech swimsuits that shook the world of swimming, how they helped athletes improve their times, and why FINA decided to regulate them.
At the World Aquatics Championships held in Rome, a staggering 43 world records were set. The swimming world witnessed a wave of record-breaking performances, including a new world record in the men’s 400-meter freestyle—a mark that had long stood unbroken. One of the factors cited behind these performance improvements was the rapid advancement of high-tech full-body swimsuits at the time. Swimsuits from various manufacturers were in use, and full-body swimsuits made of impermeable synthetic resin—such as Arena’s “X-Glide”—were among the products that symbolized the so-called “super suit” era. In fact, César Cielu, wearing the “X-Glide,” set a world record of 46.91 seconds in the men’s 100-meter freestyle. In swimming, where 0.01 seconds can decide the outcome, as records continued to fall one after another, high-tech swimsuits garnered attention as equipment that significantly influenced athletic performance. Behind the ability of a single thin swimsuit to influence records lay a variety of technologies combining materials science, fluid dynamics, and ergonomics. World Aquatics also explains that 43 world records were set at the Rome Championships at that time, leading to subsequent changes in swimsuit regulations.
If we consider the sport of swimming from a mechanical perspective, it is easy to understand the fundamental goal of high-tech swimsuits. Swimmers must move forward by generating propulsion while overcoming water resistance while maintaining proper buoyancy. In mechanical terms, this is the process of using buoyancy to maintain body posture, minimizing fluid resistance, and generating propulsion through the movement of the arms and legs. Therefore, the primary purpose of high-tech swimsuits at the time was to help swimmers maintain a streamlined body shape, reduce unnecessary resistance, and sustain efficient posture and movement. To achieve these functions, technologies from various fields—including materials engineering and fluid dynamics—were utilized.
At the time, some high-tech swimsuits utilized impermeable or low-permeability synthetic materials, such as polyurethane or polyethylene, which could significantly reduce water penetration. For example, Arena’s “X-Glide” was known at the time as a representative “super suit” made of pure polyethylene. These materials and the swimsuit’s design helped maintain a smoother body shape by compressing the swimmer’s body while absorbing almost no water. In swimming, it is particularly important to maintain an efficient posture close to the water’s surface, as excessive submersion can increase frontal area and drag. The impermeable swimsuits of that era were thought to offer advantages in terms of buoyancy and body shape maintenance, and this was considered one of the factors contributing to improved records. Subsequently, the International Swimming Federation (FINA) imposed specific regulations on buoyancy and permeability to prevent swimsuits from providing excessive buoyancy.
When a swimmer accelerates their limbs and body in the water, it is not just the swimmer’s body that moves, but the surrounding water as well. The phenomenon in which the fluid accelerates along with the swimmer, making it appear as though the object’s inertial mass has increased, is called the “added mass” effect. Since swimmers must generate not only their own body movement but also the flow of the surrounding fluid, they expend additional energy accordingly. However, rather than simply explaining that high-tech swimsuits directly reduced “added mass” itself, it is more accurate to view them as contributing to reduced overall fluid resistance and unnecessary movement by compressing the body’s surface, stabilizing posture, and creating a more streamlined body shape in contact with the water. Actual studies have reported that full-body high-performance swimsuits reduce drag and energy expenditure during swimming compared to standard swimsuits, and can increase the distance traveled per stroke at the same stroke rate.
Technologies that utilize microstructures on surfaces to reduce hydrodynamic drag have long been studied in the development of sports equipment. A prime example is the “riblet.” Riblets are a technology that involves arranging very small grooves or protrusions on a surface in a specific direction to suppress lateral flow generated in the turbulent boundary layer and reduce frictional drag. This is often described as a biomimetic technology inspired by the microstructure of shark skin. In the past, attempts were made to apply these hydrodynamic concepts to the surface structure and material design of some high-performance swimsuits. However, it is inaccurate to explain the operating principle of riblets simply by stating that small vortices act only on the tops of the protrusions, thereby reducing the surface area in contact with the water. The key lies in the fact that appropriately designed microscopic grooves can reduce drag under specific conditions by controlling the turbulent flow patterns and lateral motion near the surface.
Furthermore, high-performance swimsuits of that era utilized highly water-repellent surface treatments and smooth materials to minimize water penetration into the suit or water pooling on the surface. While some swimsuit technologies utilized surface treatments similar to fluorocarbon-based water-repellent coatings, it is inaccurate to simply refer to all advanced swimsuits as “Teflon-coated swimsuits.” A more important characteristic is that they were comprehensively designed based on various factors, including the material’s inherent low water permeability, surface smoothness, body compression, and the placement of seams and panels. In addition, highly elastic and compressive materials were expected to tightly hug the swimmer’s body, suppressing unnecessary body movement and helping maintain a more streamlined posture. While this compression can help reduce the jiggling of muscles and soft tissues and stabilize posture during competition, it is difficult to make a blanket statement about the extent to which it directly reduces muscle fatigue, as this can vary depending on the type of swimsuit, the swimmer, and competition conditions.
As swimming records improved rapidly due to this technology, the International Swimming Federation (FINA, now World Aquatics) tightened regulations on high-tech full-body swimsuits. FINA restricted swimsuit materials to textile fabrics and established standards to prevent non-permeable materials from having an excessive impact on performance. Men’s swimsuits were prohibited from extending above the navel or below the knees, while women’s swimsuits were prohibited from covering the neck, extending beyond the shoulders, or reaching below the knees. Technical standards regarding swimsuit thickness, permeability, and buoyancy were also established. The standards set at that time limited the buoyancy effect of the swimsuit itself to 0.5 newtons or less and required a certain level of permeability. These basic regulatory principles remain in effect today, and swimsuits used in international competitions must be products approved by World Aquatics.
The implementation of regulations on high-tech swimsuits brought about changes in the way swimming records were set. In fact, studies comparing records from the period when high-tech swimsuits were permitted with those from after the regulations were implemented showed that high-performance swimsuits had a significant impact on improving athletic performance. In particular, a decline in competition times was observed in certain swimming strokes and among specific groups of athletes after high-tech swimsuits were banned. However, as time passed, advancements were made in training methods, nutrition management, start and turn techniques, underwater motion analysis, and athlete development systems, enabling athletes to once again achieve results that surpassed the records set during the “supersuit” era. Many of the world records once set in high-tech swimsuits were subsequently broken by a new generation of athletes. This demonstrates that while equipment such as swimsuits can influence athletic performance, human physical abilities and training techniques also continue to evolve.
That said, it is worth considering whether we should view the development of advanced equipment as inherently negative. Simply using high-quality equipment does not mean that an athlete who has not trained sufficiently can immediately rise to the top of the world rankings. Ultimately, an athlete’s physical abilities, technique, and training remain at the heart of the sport. When science and technology are combined with an athlete’s effort, they can produce better records and provide motivation to challenge human limits. The process of researching and improving equipment can also be seen as a crucial pillar of sports development. Not only swimsuits, but also pole vault poles, golf balls and clubs, table tennis paddles, track and field shoes, and bicycles—countless pieces of sports equipment have continuously evolved to improve records and athletic performance.
When records that had long remained virtually unchanged suddenly improve dramatically with the advent of new equipment, concerns may arise that the traditions and fairness of the sport are being undermined. Conversely, there is also the view that such technological advancements are part of the accumulated efforts humans have made to go faster, higher, and farther. The key is not to reject technology itself, but to establish reasonable standards that determine the extent to which equipment assistance should be permitted in order to preserve the essence of sports—namely, competition based on individual ability and skill. The reason World Aquatics continues to maintain a list of approved swimsuits and manage technical standards regarding swimsuit materials and construction can be seen as an effort to maintain this balance.
One might then ask whether doping—the use of performance-enhancing drugs—should also be permitted, since it is another form of technical effort aimed at improving records. However, technical advancements in equipment and the use of banned substances are treated as distinctly separate issues under sports regulations. For sports equipment, approval standards can be established to ensure all athletes can use it within set regulations, and the range of performance can be controlled. In contrast, doping—the act of artificially enhancing athletic performance through prohibited substances or methods—not only undermines fair competition but can also pose serious risks to athletes’ health. Consequently, international sports organizations, including World Aquatics, establish sport-specific technical regulations to define permissible ranges for equipment, while prohibiting doping through separate anti-doping regulations.
At the time, the regulation of high-tech swimsuits sparked various controversies and criticisms regarding the relationship between swimsuit manufacturers and the International Swimming Federation, as well as the process by which regulations were fully implemented—specifically, how equipment from a particular manufacturer initially drove record improvements before products from competitors emerged. Around the time of the Beijing Olympics, Speedo’s full-body swimsuits garnered significant attention, and the race for records intensified further as competitors, including Arena, introduced new products that actively utilized non-permeable materials. However, there is insufficient evidence to conclusively assert that these regulatory changes were driven by a relationship with a specific company. According to the official announcement by the International Swimming Federation (FINA) at the time, the swimsuit issue was discussed primarily in terms of technical factors such as buoyancy, thickness, permeability, and materials, and a committee comprising scientists and athlete representatives was formed to establish approval procedures and measurement standards. Ultimately, it is reasonable to view the core of the debate not as one driven solely by the interests of a specific company, but rather as a question of how far technological advancement should be permitted and what standards should be set to ensure that equipment does not overshadow the athletes’ abilities.
Sports science is widely applied not only in swimming but also in various record-based competitive sports where a difference of 0.01 seconds can decide the outcome. Clap skates in speed skating are a prime example. Developed and widely adopted in the Netherlands, clap skates are designed so that the heel portion of the blade can detach from the boot, allowing the ankle to extend more naturally while ensuring the blade remains in contact with the ice for a longer period. This equipment innovation had a significant impact on improving performance in speed skating and has since become the de facto standard on the international stage. It is an example that demonstrates how consistent technological development and scientific analysis—in addition to elite athletes’ physical abilities and training—can be crucial factors in sports competitiveness.
Ultimately, the most important question left by the now-banned high-tech swimsuits is not simply a choice between “allowing technology” or “banning it.” The core issue is determining how far technological advancement should be permitted in sports and where to draw the line between an athlete’s effort and the performance of their equipment. In the past, “super suits” altered the way swimmers interacted with water, contributing to a wave of world record-breaking performances; as a result, the international swimming community established new rules to limit the performance of such equipment. Even today, competitive swimsuits incorporating advanced materials, compression technology, sewing techniques, and hydrodynamic design continue to evolve; however, impermeable full-body “super suits” like those of the past are no longer permitted in international competitions. The history of high-tech swimsuits clearly demonstrates that sports do not rely solely on athletes’ physical abilities but evolve through the constant interplay of science, technology, equipment, and rules.
