Brief, Jammer or Shorts: What to Actually Wear for Lap Swimming
Swim brief, jammer or board shorts for lap swimming: what each one does to your drag, your kick and your kit bag, and which of them belongs in a pool.
The Suit Ban of 2010: When Swimming Outlawed Its Own Records
The 2010 FINA ban on polyurethane swimsuits: what the suits actually did, why 43 records fell in eight days in Rome, and how the brief came back.
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On the evening of 28 July 2009, in the Foro Italico in Rome, a German swimmer named Paul Biedermann won the 200 metres freestyle and broke Michael Phelps's world record. Biedermann was, by any reasonable measure, not the better swimmer that year. He was wearing an Arena X-Glide, a suit made of polyurethane. Phelps was in a Speedo. Two days earlier Biedermann had taken Ian Thorpe's 400 metres freestyle record, a mark that had stood since 2002 and had been widely regarded as untouchable.
Phelps's coach Bob Bowman spent the rest of that week telling anyone who would listen that the sport had a problem it could no longer pretend was a training question.
By the end of those championships, 43 world records had gone. Not 43 in the year. Forty three in eight days of racing in one building. It is the single most absurd statistic in the modern history of Olympic sport, and it is the reason the men's swim brief exists in its current form.
What the suits actually did
The physics is worth getting right, because the popular version, that the suits "made you float", is only about a third of it.
A swimmer fights three kinds of resistance. Friction drag is the water dragging along the surface of the body. Form drag is created by the shape and attitude of the body pushing a hole through the water. Wave drag is energy lost making waves at the surface. The polyurethane suits attacked all three at once, which is why the gains were so large.
On friction, polyurethane presents a smooth, hydrophobic surface with a lower drag coefficient than human skin. Speedo's own claim for the original LZR Racer was a 24 percent reduction in skin friction drag against its previous suit, after testing in a NASA wind tunnel. A marketing number, but the direction of it was not in dispute.
On form drag, two things happened. The suits compressed the body into a narrower, more consistent shape, roughly the same reason a cycling skinsuit exists. More importantly, the sealed non-permeable material trapped air against the body. Trapped air is buoyancy. Buoyancy lifts the hips and legs towards the surface, and higher legs present a smaller frontal profile. Every coach in the sport knows body position is worth more than almost anything else, and the suits handed it out for free.
The third effect is the one swimmers talked about privately. Compression holds the muscle, damps oscillation, and appears to delay the point at which a set of legs stops working. That is why records fell disproportionately in the back half of races, and why distance swimmers suddenly found a final fifty they did not previously own.
Put together, you had a garment that reduced every kind of drag, improved body position, and postponed fatigue. Calling it a swimsuit was generous.
Two years of an arms race
Speedo launched the LZR Racer on 13 February 2008. It was not fully polyurethane; it was a woven elastane and nylon base with bonded polyurethane panels, ultrasonically welded seams on the top models, and internal compression panels that held the swimmer in something close to a corset.
World records started falling within days. At the Beijing Olympics that August, swimmers wearing the LZR took 23 of the 25 world records set at the Games. At the European Short Course Championships in December 2008, 17 records went in a single meet.
The competitive response was inevitable and it was worse. If bonded polyurethane panels were fast, a suit made entirely of polyurethane would be faster. Through the first half of 2009 the market filled with fully non-textile suits, the Arena X-Glide and the Jaked 01 among them, and the manufacturer began to matter more than the athlete. Contracted swimmers lost to lesser rivals in better suits. Some broke contracts. Some wore two suits at once. Meets were decided in the changing room.
FINA, the Fédération Internationale de Natation and the sport's governing body at the time, tried a technical fix first. At a meeting in Dubai in March 2009 it set limits on suit thickness and buoyancy and introduced an approval process. It did not work, largely because a limit that permits polyurethane at all permits an arms race in polyurethane.
The sport decides it has broken itself
Here is what makes the 2010 ban genuinely unusual as a piece of sports governance. Nobody cheated. Every suit worn in Rome was on the approved list. The rules were followed exactly, and the sport still concluded that the result was worthless.
That conclusion rests on an argument about what a sport is for. Swimming is a comparison across time. The whole emotional architecture of the sport, the record progression, the sense that a mark set in 1976 means something against one set in 2016, depends on the assumption that the medium and the equipment are constant and the variable is the human being. Once the equipment becomes the variable, a world record stops being a claim about a person and becomes a claim about a procurement decision.
Swimming, which had less equipment than almost any sport and had therefore never needed to think about it, discovered in about eighteen months that it had accidentally become an equipment sport.
On 24 July 2009, during those same Rome championships, the FINA Congress voted overwhelmingly to ban body-length suits and non-textile materials. The FINA Bureau confirmed on 31 July that the new rules would take effect on 1 January 2010, with previously approved suits remaining legal to the end of 2009. The competition finished. The suits were worn for another five months. Then they were gone.
The rule, in its own words
The regulation is short and it is worth reading closely, because it is the document that produced every men's racing swimsuit made since.
Material. Only textile fabric is permitted, defined as material made of natural or synthetic yarns constructed by weaving, knitting or braiding. That single clause is the whole ban. Polyurethane sheet is not woven, knitted or braided, so polyurethane is out, and no amount of clever engineering gets it back in.
Thickness. A maximum of 0.8 millimetres.
Buoyancy. No more than 0.5 newton after the suit has been subjected to a vacuum. In plain terms, a suit is not allowed to hold air.
Permeability. The material must let water through at a rate above a specified threshold, which is the same rule stated from the other direction: the suit must not seal.
Coverage, men. A swimsuit shall not extend above the navel nor below the knee.
Coverage, women. A swimsuit shall not cover the neck, extend past the shoulders, nor extend below the knee.
Construction. No zippers or other fastening systems, no external applications or stimulation devices, and seams limited to what is functionally necessary.
Read the men's coverage line again. Navel to knee is the outer boundary, a maximum rather than a specification. Everything smaller is legal, which means the entire legal range for a man at the highest level of the sport runs from a jammer at one end to a swim brief at the other, and nothing else exists Brief, Jammer or Shorts: What to Actually Wear for Lap Swimming.
What men were left holding
The morning of 1 January 2010, every elite male swimmer in the world owned exactly two options.
The jammer, a knitted textile short reaching to above the knee, compressive, seamed to sit flat, and the choice of most sprinters and anyone who likes the reassurance of leg compression competition jammer. The swim brief, which covers the minimum, weighs almost nothing, adds no wetted surface area at all, and is what a great many distance swimmers, water polo players and training squads went straight back to Your First Speedo: The Complete Buying Guide.
That was it. A garment category that had spent two years expanding into a full-body technical system was legislated back to two shapes, both of which had existed since the 1960s and one of which had been made famous by a knitting mill in Sydney Speed On In Your Speedos: The Sydney Knitting Mill That Named the Swim Brief.
The consequence nobody predicted was what it did to the ordinary swimmer. When the elite level was in full-body suits, everything below it drifted the same way, and the pool became a place where covering up read as serious. After the rule, the fastest men on earth were on the blocks in a brief or a jammer at every televised meet, in perpetuity. It is hard to overstate what that has done to make the swim brief legible again to people who had absorbed twenty years of embarrassment about it The Speedo Comeback Is Real (and We Have the Numbers).
The records that never went away
FINA did the ban and then did not do the obvious follow-up. The records set in the suits were never annulled. They went into the book and they stayed there.
The suits were legal at the time, and swimmers who had broken no rule would have had achievements deleted for a governance failure that was not theirs. The argument the other way is that the book now contains marks describing a sport that no longer exists.
What actually happened is that the sport waited them out. Instead of an erasure there has been a slow attrition, distance and technical events falling first and a handful of sprint marks proving extraordinarily stubborn, roughly what you would expect if the suits helped most where drag and body position dominate. Every time one goes, somebody writes a piece about it, and the pieces are always slightly moving, because the swimmer breaking the record is beating a garment as much as a person.
The organisation has since changed its name. FINA announced in December 2022 that it would rebrand as World Aquatics, phased in through 2023. The rule it wrote in Rome has outlasted the body that wrote it.
Why the ban was the making of the swim brief
Before 2008, the men's racing swimsuit was drifting. The trend line ran from brief to jammer to long-leg to full body, and every step was sold as more serious, more technical, more professional. There was no reason to believe it would stop. Had the suits been permitted, the endpoint was obvious. The interesting decisions would have been made by materials scientists, the barrier to entry would have been the price of a suit that lasted a handful of races, and the garment of the sport would have been a sheath nobody could wear anywhere except a start block.
The textile-only rule killed that trajectory in one clause. It did not just ban a product. It closed the direction of travel, permanently, by defining the legal space in terms of what the garment may not be rather than what this year's technology can achieve. Nobody has found a way around it in fifteen years, which is rare in sports regulation.
What that left is a category where the garment is more or less finished and the differences that remain are real ones: fabric, chlorine resistance, cut, how a seam sits, how long a suit holds its compression before it goes slack Chlorine, Salt and Sun: How to Make a Swim Brief Last. A polyester or PBT brief bought now is recognisably the same object as one bought in 1975, made better, and it will outlast a polyurethane suit by a factor nobody would believe PBT racing swim brief.
It also left the swim brief with something it had lost and could not have recovered on its own: an unarguable functional case, demonstrated on television, by the fastest people alive, several times a year. You cannot buy that kind of rehabilitation. Swimming had to nearly destroy itself to produce it The Sea Swimmer's Case for the Swim Brief.
Which is the part worth sitting with. A governing body looked at the most exciting two years of racing in its history, understood exactly what those two years were worth, and voted to make them impossible. Very few institutions of any kind ever do that. The men on the blocks in Paris and Los Angeles wearing not much at all are the result, and so, at one remove, is every club squad in the world in matching briefs on a Tuesday night The Club Print: Custom Swim Briefs and the Best Kit in Sport.
Questions people ask
Why were polyurethane swimsuits banned in swimming?
Because they made the equipment more important than the athlete. Polyurethane suits reduced friction drag, compressed the body into a more hydrodynamic shape, and trapped air, which raised the swimmer's legs and cut form drag. World records fell at an absurd rate, including 43 at the 2009 World Championships in Rome alone. FINA, the sport's governing body at the time, voted in Rome on 24 July 2009 to ban non-textile and body-length suits, with the rules taking effect from 1 January 2010.
What are the current rules for men's swimsuits in competition?
Men's competition suits must be made only of textile fabric, meaning natural or synthetic yarns woven, knitted or braided. The suit may not extend above the navel or below the knee. Maximum thickness is 0.8 millimetres, buoyancy is capped at 0.5 newton, the material must be permeable rather than sealed, and zippers or other fastening systems are not allowed. In practice that leaves two legal shapes: the jammer and the swim brief.
Were the world records set in the banned suits cancelled?
No. FINA banned the suits but never annulled the marks set in them, on the grounds that the suits were legal when worn and the swimmers had broken no rule. The records went into the book and stayed there, and have been removed only by being beaten. Distance and technical events have largely moved on, while a small number of sprint records from 2009 have proved remarkably durable.
Did the suit ban bring back the Speedo style swim brief?
It brought it back at the elite level, which is where the influence comes from. Since 1 January 2010 the only legal men's racing suits have been the jammer and the brief, so every major televised meet since has shown the fastest swimmers alive in one or the other. That constant, unembarrassed visibility has done more to normalise the swim brief than any advertising campaign.
What is the difference between a jammer and a swim brief for training?
A jammer reaches from the waist to above the knee and gives leg compression, which some swimmers find supportive over long sets. A swim brief covers the minimum, has less wetted surface area, dries faster, packs to nothing and gives complete freedom at the hip, which matters for breaststroke and butterfly kick. Both are legal at every level, so buy the one you will actually get in the water wearing polyester training swim brief.