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The Aquatic Signature And Flotation

Feb 18, 2009  - Craig Lord

Suit Week Sequel – Part 2: In the meeting room in Lausanne on Friday will be people who want to make suits that enhance performance. FINA is now ready to remind them where the suit fits, say insiders, after a blip that allowed market forces to rule the pool for a short spell. And for those who hope that a solution will be impossible because of the complex nature of the issue, there is bad news: the answer is out there and it's something we can all understand

In 2008, FINA and others abdicated their duty of care to the sport of swimming by allowing the spirit of Rule SW10.7 to be broken. In doing so, they handed the sport over to market forces. Some of those forces have now seen the light, if only because their commercial future is at stake. Others among those forces, largely newcomers to the race pool, want no return. Indeed they want to press on down the stream towards a fast-fabric flotation solution to the sport that can then, as they would have us believe, help to sell big-brand equipment (just like golf and tennis and...etc).  The coffers would pour over with new funds, a market would have been created.

And swimming as we have known it would have been lost forever. In 2008, swimming entered the realm of "in danger of extinction". In its place by the close of the year was an equipment-based sport that diminished the value of performance and the achievement of swimmers, coaches and others who contribute to excellence through endeavour.  

A fly on the wall in Lausanne on Friday will surely hear people in the room refer to "change, natural evolution and progress".What happened in 2008 represented no such thing. It represented regime change, the replacement of one sporting culture by another. In that meeting, some will stick to the line that luddites resist change. I read the words of one party to the talks on Friday who wrote that I would have us all return to wooden starting blocks and wool. Bullshit. Neither I nor any of those who have understood the crisis of 2008 are luddites. A much more apt description, if one must be used, is that of conservationist (a status that allows for natural evolution without an injection of alien DNA).

Of late, the conservationists among us have been led to believe that the only way out is a complex scientific solution that must be fed to us by folk with brains that could make Einstein quiver. The truth lies somewhere else. As you read what follows and our conclusions before Friday, rid your mind of men in white coats chalking up calculations so clever and deep as to be beyond the ken of us all. This is an issue that can be understood not only by scientists in ivory towers but by swimmers and practitioners, coaches and officials. 

In refusing to accept that the abhorrent place swimming travelled to last year was down to matters I could not understand, I went in search of knowledge. What I found was something we can all understand and most are likely to be happy to subscribe to. 

On my journey, I came across a name I had seen before. Milt Nelms is often described as a stroke guru, an aquatic equivalent of a horse whisperer, by world-class swimmers ho have been guided towards deeper understanding of how they interact with water, how they sit in water, how they get the most out of their passage through water. He is one of those figures whose name pops up in the mixed zone as swimmers explain what helped to turn them into faster fish. 

When Ian Thorpe announced his retirement, he paid tribute to the work he had done and was doing with Nelms, saying of the American’s approach: 

"I transformed the way I swim, and trained. I loved both. I felt extraordinarily alive, and knew I was lethal with my new stroke. It's a way of swimming we should all learn as kids because it is so hard to pick it up as an adult, when you've been drilled full of science-based technique. It took me ages to get it, and I only know a fraction of what Milt knows. But it's such an enjoyable way to swim. I love the stroke. I believe if swimming is to move forwards, the Milt Nelms holistic approach is the only way to go. It's such a healthy way of swimming and training, and the only way that swimming is going to get significantly faster. I won't be the one to show it to the world, but others will seek Milt out. His methods won't be adopted initially, because people are so set in their ways of doing things, and you must be open to lateral thinking."

Nelms is a key contributor to a body of knowledge, some of which is available to the swim coaching community at paramatrix.org. If you're not familiar with the site, take the plunge into a place stacked with treasure for those who wish to travel faster through water, in any suit. The website is run by Alex Nikitin, a scientist-coach who designed and wrote the software for the race analysis programme used by USA Swimming.

The gem in the knowledge to be gleaned at parametrix is the concept of Aquatic Signature, the very basis of stroke design and the focus on both velocity and duration material. First a little background about Nelms for those unfamiliar with work that must be considered central to any serious efforts to conserve the special status of swimming in the world of sport.

A former member of USA Swimming Board of Directors, Nelms's collaborative work with Prof. Bill Boomer on swimming technique was designated one of top 25 contributions to USA Swimming in it’s first 25 years. In other words, work that has been key to keeping the USA on the crest of a wave as the world aquatic superpower for many a long year. Nelms - whose wife is Shane Gould, a triple Olympic champion who has devoted a great deal of energy to promoting the health benefits of swimming for all ages and shown that swimming is for life, not just for the under 20s and under 30s - has worked as a confidential consultant to coaches, NOC and NGB bodies, athletes, learn to swim organizations (including a swim school which became USA Swim School Association Swim School of the Year), swim clubs, and other competitive swimming organizations, and in commercial sporting goods manufacturing. The USA is not the only nation to benefit from his work: he has worked in no fewer than 24 countries and has been the lead speaker at conferences in 15 of those countries. That excellent work includes six FINA solidarity clinics and stretches to advising educational/medical bodies and organizations and designing movement, rehabilitation, and athlete development programmes in non-swimming Olympic and non-Olympic sports. 

What follows below is an article penned by Nelms that I came across in my search for understanding. I reproduce it with kind permission and with nothing added or taken away. It gets to the very heart of the 2008 malaise – and should be read alongside these simple sketches that explain the concept of Aquatic Signature.


By Milt Nelms

The water is thick and heavy. Humans moving through the water expend energy. The faster they move, the more energy they expend.

When flotation is present in swimwear, swimming changes. The amount of change depends upon the amount and the location of the flotation within the swimwear.

The Aquatic Signature and Swimming

The Aquatic Signature

The human body naturally shapes itself in the water in a typical way, which is called the Aquatic Signature. The Angle and other traits of the Aquatic Signature vary greatly from person to person, but the basic character is the same for all human beings. Refer to Sketch 1 .

The aquatic signature is an indication of the amount, and the location, of buoyancy that is naturally in a person’s body. The chest contains the lungs, so this part of the body floats upward. Everything from the lungs downward towards the feet is heavier than water, and tends to sink (Tummy, hips, legs). Everything above the lungs tends to sink as well. (Shoulders and arms, head and neck). Refer to Sketch 2 .

The Aquatic Signature is a poor swimming position, especially when trying to go fast. A position that is horizontal and close to the surface is a much better position for swimming. Refer to Sketch 3.

A swimmer’s most common way of moving from an Aquatic Signature to a horizontal position close to the surface, is to use forceful leverage by kicking downward on the water and while lengthening the body. Refer to Sketch 4.

Refining this level swimming position is one of the things that makes faster swimming possible.

Green, Yellow, and Red Effects:

There are three resistant effects that slow the swimmer down, and require energy to overcome.

Listed in order from least aggressive to most aggressive, the effects are:

  • 1. The resistance of the water as it passes over the skin, hair, and material of the swimming suit. (Green Effect). Refer to Sketch 5.
  • 2. The resistance of the body as it creates a hole in the water. (Yellow Effect). Refer to Sketch 6.
  • 3. The resistance of the waves and turbulence of the water as the body moves forward (Red Effect). Refer to Sketch 7.

The least important of these three Effects in competitive swimming is number 1, (Green Effect). More important is number 2 (Yellow Effect), and most important is number 3, (Red Effect).

The quality in point number 2, (Yellow Effect), that causes problems is the size of the hole the body makes in the water. The bigger the hole, the more of the heavy, thick water that is displaced, and the further that (the water) will need to go to get out of the way of the swimmer.

The quality in point number 3, the Red Effect, that causes problems for the swimmer is created by the size, direction, and amount of turbulence in the waves made by the body as it moves forward. The hole in the water needs to open up and close behind the swimmer. This fact, plus the forms and fluctuations in the body, are what cause the Red Effect.

The bigger the wave, the more agitated the wave, and the more oblique the angle away from the body of the wave, the greater the Red Effect. Increase of resistance

The resistance made by the three resistance traits increases as the body moves faster through the water.

The following statements are approximate, but generally accurate: 

  • The effort needed by a swimmer to overcome the Green Effect in point number 1 increases steadily as the swimmer goes faster.
  • The resistance in point number 2, the Yellow Effect, has an exponential increase as the swimmer goes faster.
  • The resistance in point number 3, the Red Effect, has an exponential increase, much greater than the exponential increase in the Yellow Effect of point number 2, as the swimmer goes faster. 

To summarize - If a swimmer is swimming at a fast speed and increases his speed slightly:

  • The Green Effect also increases slightly.
  • The resistance of the Yellow Effect increases much more than in the Green Effect.
  • The resistance in the Red Effect also increases a lot, much more than the increase of resistance of the Yellow Effect.

Growth of resistance as swimming speed increases moves from Green, then to Yellow, then to Red. 

Flotation and the swimsuits

Flotation has a very big effect on the Yellow Effect, which is made by the size of the hole the body makes in the water, because it makes the hole in the water smaller by raising the body upwards.

The Yellow Effect, and the Red Effect, which is caused by waves, have a close relationship.

If the Yellow Effect is reduced, then Red Effect is reduced also.

When a swimsuit adds flotation, the water thus needs to travel less distance to get out of the way of the body, reducing the both the Yellow Effect, and the Red Effect.

However, the reduction of the Red Effect helps the swimmer much more than does the reduction of the Yellow Effect. This is because the exponential factor in the Red Effect is much higher.


The main performance-enhancing outcomes of adding flotation to a swimsuit are:

Faster Speed

Top speed increases with the same amount of power, so 50’s would get faster. Without doing anything to increase power, a swimmer will get faster.

Better duration

It will take less energy to maintain a given speed for events that require endurance. Without becoming more fit, a swimmer will be able to go further at the same speed, or, add speed over a distance without increasing effort.

Extra Swimsuits

Wearing more than one flotation swimsuit will, obviously, increase flotation. One suit raises the body, two suits raises the body more, three suits even more. A body which is higher in the water makes a smaller hole, which results in even faster and easier swimming.

Leverage and swimming

Force leverage is commonly used (by kicking downward) to move from the poor swimming position of the Aquatic Signature into a much more advantageous horizontal position. Refer to Sketch 4.

Three issues can be strongly affected when flotation is added to the legs of a swimsuit:

  • 1. The length of a swimmer's legs (both their actual linear length and their percentage of overall body length) can cause the effective weight of the legs to increase as they get longer. In a similar way the effective weight of the legs can be decreased if the legs are shorter. In either case flotation in the legs of a swimsuit will make the legs lighter.
  • 2. The density of tissues varies from individual to individual. The make-up of bones, connective tissue, and muscle can make the legs literally heavier or lighter. Again, flotation in the legs of a swimsuit will make the legs lighter in either case.
  • 3. Strength and fitness in the deep axial region will be reduced if flotation is added to the legs to make them lighter. (The deep axial region a part of the body popularly referred to as the “core”.) This part of the body is used when the legs are involved in kicking downwards in order to help bring the body to a horizontal position. Strength and fitness of this deep axial region can be less developed if a swimsuit with flotation in the legs is used.

Note: The results of flotation in points one and two will change the angle of the swimmer’s basic Aquatic Signature. (These changes will vary from individual to individual). Refer to Sketch 8.

If less force leverage is needed to get the body to a horizontal swimming position, which can be accomplished with leg flotation in a swimsuit, the results will be:

Faster Speed

Less of the kicking energy will be expended downward to lift the legs. This will leave more of the kicking energy available for forward propulsion.

Better duration

Less energy will be needed to keep the legs close to the surface. This will help swimmers in longer races, or at the end of shorter races.


Swimming is unique among sports, in that it has always been about the direct interaction of the human organism with the water environment. FINA rules about equipment reflect this unique trait of swimming. Flotation assistance introduces an apparatus into swimming, which means that we are not talking about evolution of a sport. We are talking about replacing a unique non-equipment sport with a different sport, one which utilizes equipment.


So ends Nelms’s paper, a piece of work that explains to us all what happened in 2008. It identifies where swimming must look to find a relatively simple answer to a problem cluttered with unhelpful and mysterious explanations that some would have us all believe require complex scientific solutions. No such things are needed – as we will see in our final articles tomorrow, before the meeting on Friday in Lausanne.