Why Ankle Flexibility Is the #1 Predictor of a Fast Swimmer

Every swim parent has watched it: a swimmer who works hard on every kick set and still goes nowhere underwater, while the kid in the next lane seems to glide off every wall. Most of the time the difference is not effort or talent. It is a joint. Here is what I see on deck, why we start every practice at camp with mobility, and what your swimmer can do about it at home.

What is the number one predictor of a fast swimmer?

Hungary produces a remarkable number of fast swimmers for the size of the country, and their coaches are known for being tough. When they go to the youth swimmers to figure out how talented someone really is, the first thing they check is not a best time. They check everybody’s ankle flexibility. In their experience it is the number one predictor of how far a swimmer can go.

The reason is physics. If a swimmer kicks with stiff, flexed feet, the top of the foot pushes water forward. They are literally kicking themselves backwards. A loose, flexible ankle does what a fin does: it bends, creates a whip, and catapults the water back. That is why everybody is so fast with fins on. We cannot make our feet bigger, but we can make them almost as flexible as a fin.

Look at any of the great underwater kickers and you will see ankles and feet that move like a dolphin’s tail. Milorad Čavić, who coaches with us, had some of the fastest underwaters of his era and came off the start ahead of Phelps. He talks about ankle flexibility constantly.

If your swimmer has stiff ankles, they will always feel bad at kicking, because physically it is impossible to be fast. Remove that limitation and the whole picture changes.

What happens when a swimmer fixes their ankles?

The first change is physical: being fast becomes possible. The second change is the one parents notice. The swimmer feels it, thinks “this feels pretty amazing”, and starts to see themselves as an underwater kicker. So they do more of it. Because they do more of it, their lung capacity grows and their confidence builds.

Then they swim their next 200 backstroke and they are suddenly seven or eight metres underwater off every wall. Half a year later it is ten. None of that starts until the physical limitation is gone, and that is what mobility does.

If underwaters are the specific weakness, we went deeper on the technique side in how to improve the underwater dolphin kick.

Is my swimmer too stiff? A test you can do tonight

Ask your swimmer to stand still and turn their shoulders left and right without turning their head. Some swimmers simply cannot do it: the head comes with the shoulders every time. Now imagine swimming freestyle like that. Rotation, breathing and the catch all suffer.

Then watch their streamline. We have 15 year olds on camp whose arms cannot get anywhere near their ears. If a swimmer is stiff like a wooden board, nothing in the water will work, starting with the streamline. The good news is that this can be fixed quickly.

Why is neuroathletics faster than stretching?

The old-school approach is to hang off a wall and stretch for minutes at a time, for weeks, months, sometimes years. It works, slowly.

My sister, Coach Rebecca, started as a yoga teacher and went down the rabbit hole into breathing and neuroathletics. The idea is that when mobility is limited, the body has learned that there is a danger zone past a certain point. The brain first has to tell the body that it is safe. When it does, the body lets go, and you get a lot more movement very quickly, without minutes of stretching.

I am the proof that you do not need to understand it for it to work. I used to have a shoulder that was fine one way and cracked going back. Rebecca tested it, had me fix my eyes on one point and shuffle left and right for five or ten seconds, and we tested again. The shoulder was more mobile. I remember the exercise, I do it before I bench press, and my shoulder is good to go.

The best-known name associated with this kind of work is Tom Brady. People laughed at the strange drills he did with his body coach, covering one eye, looking through coloured lenses. He has credited that work for his longevity in a sport built on getting hit.

One note for the routine itself: long, deep stretching or a full yoga session straight before training is not ideal. It leaves the muscles too long and relaxed to train hard. Keep the long stretching after practice or on its own, and keep the pre-pool routine short and activating.

Should my teenage swimmer lift weights or do mobility?

Mobility first. We see it every summer: strong 13 and 14 year old boys who feel small next to their teammates and start lifting at home, often unsupervised, learning from YouTube. I admire the drive. But two years later they are bigger and tighter, and tight is slow in the water. You have never seen a bodybuilder win a swim race.

This summer a 16 year old wanted to keep going to the gym at camp. By the end of the ten days he understood what mobility does for him, and what years of lifting had done to his range of motion without him noticing. He went home and swapped his gym time for mobility. After camp he set personal bests in all seven or eight of his races.

The pros already know this. Caeleb Dressel starts his Monday morning with an hour of mobility, does more on other days, and turns up early to practice to do his routine. And when Peter Mankoč decided to come back for a shot at the Slovenian nationals, the first thing he said was that he needed his mobility back.

Mobility also protects. Most swimming injuries are not sudden, they build over time, and a lot of shoulder trouble can be prevented rather than iced after every session.

How do Swimpros camps train mobility?

Mobility is one of our four pillars, alongside flume and technique work, speed development, and confidence building. Every practice starts with 30 to 40 minutes of mobility with Coach Rebecca, morning and afternoon: classical joint preparation for shoulder health, plus the modern work on the spine (the engine of the underwaters), the ankles, and the hips and knees for breaststrokers.

The bigger goal is what happens after camp. Ten or eleven days on camp is a lot, but there are 354 other days in the year, and in a way those matter more. Most swimmers already arrive at the pool 10 to 30 minutes early and swing their arms the way they have for years. That time can do much more. Swimmers take the routines home, and Rebecca’s mobility, breathing, spine and ankle modules live in the Swimpros Skool classroom so they can keep using them.

Mobility pairs with other things we measure on camp. After ten days of afternoon drag sock work, the average improvement on a 15 metre underwater fly kick at one of our camps was 0.5 seconds, which over the turns of a short course 200 adds up to about four seconds. If you want the full picture of how we coach, start with how Swimpros trains.

Frequently asked questions

What is the number one predictor of how fast a young swimmer can get?
Hungarian coaches, from one of the strongest swimming countries for its size, check ankle flexibility first when they scout youth swimmers. Flexible ankles let the foot work like a fin, which is what makes a fast kick and fast underwaters physically possible.

Can ankle flexibility be improved, or is it genetic?
It can be trained. Old-school stretching works slowly, over months. Mobility and neuroathletic exercises work faster, because they teach the brain that the extra range is safe, and the body then lets go of it.

Should my teenage swimmer lift weights or do mobility?
Mobility first. Strength work during growth, especially unsupervised, makes swimmers bigger and tighter, and tight is slow in the water. One 16 year old at our summer camp swapped his home gym time for mobility and set personal bests in all 7 or 8 races after camp.

How much mobility do swimmers do at a Swimpros camp?
30 to 40 minutes before every practice, morning and afternoon, run by Coach Rebecca, a neuroathletics specialist. The routines go home with the swimmers so they can use them before practice all year.