How To Stop Your Legs From Sinking

How To Stop Your Legs  From Sinking

The  Ultimate Guide To Balance & Alignment In Freestyle Swimming


Stopping your legs from sinking doesn’t just magically happen.

The human body isn’t designed to float horizontally. Honestly, I don’t even think we were created to swim. Sinking legs is a problem practically every human faces when first learning to move through the water.

The fact is, our legs naturally sink. Keeping them up and afloat takes body control and skill. You have to learn to manipulate the forces at play to get your head, hips and heels aligned.

I’m assuming you picked up this guide because you want to know how to stop your legs from sinking.

I think that’s awesome.

It immediately tells me that you have your priorities right. Getting your alignment right is the key to faster, efficient swimming.

Don’t believe me?

Why do you think so many triathletes love their wetsuits? Why do I see so many age groupers swimming with pull buoys between their legs, all the time?

Because the wetsuit, the pull buoy & the buoyancy shorts all stop your legs from sinking! And as a result you can swim faster for longer.

If you are a runner or a cyclist transitioning into triathlon, I’ve written this guide for you.

If you’re struggling to balance out your body. If swimming a length or two exhausts you and you can’t swim without having to stop. If you want to cope better with non wetsuit legal swims. I have written this guide to help you too.

This is my attempt to teach you how to balance your body and align yourself in the water. It brings together all my knowledge on the topic. The 12,000+ words in this guide cover a lot of what I have learned from years of coaching triathletes and hours of studying them swimming. The videos and practical tips come from many late nights watching and analyzing the strokes of people just like you.

In this guide, you’re going to learn why your legs sink and the root causes of sinking legs that I see most often. I’ll show you how to address and fix each issue and answer the most common questions I get asked.

How Body Composition Affects Flotation

Have you ever said:

“I lack the natural ability to float and so I tire quickly.”

“My bone density is unnaturally heavy so I can’t swim very fast”.

“I have below average buoyancy so I can’t swim well.” 

If you’re using “natural flotation” as an excuse for your lack of progress in the water, you’re misguided. And I want to start this guide by showing you why.

I’m not going to be an asshole about it. I have worked with thousands of runners and cyclists that struggle with this. If anything, I am extremely empathetic to how difficult learning to float and balance in the water can be. 

But, your body composition is not a limiter on your ability to swim fast. Your technique, or more specifically, your ability to get into and hold the correct position is.

Yes, your body composition does play a role in how well your body floats. But your “floatability” does not affect your swim potential. At least not at the AG Triathlon swimming level. 

Stick with me as I explain why. There are some numbers involved but I’ve kept it simple and it’s worth your time to understand:


We measure floatability using something called a specific gravity ratio (sp gr)*. The lower an object’s sp gr (specific gravity ratio) the better they float. 

Water has a sp gr of 1.00, the average human body has a sp gr of 0.974**.  All this means is the average human body is less dense than water. And that means most of us humans can float to some degree. 

*Specific gravity is the ratio of the density of a substance to the density of a reference substance ( 


Despite the body (as a whole) having a lower sp gr than water, only a small percentage of tissues in the human body floats very well.

What Floats? 


The only real floatable part of the human body is the lungs. 

Your lungs are like two big bags in your chest that fill with air, like balloons. The bigger your lung capacity, the more air you hold in your chest and the higher your upper body will float.  

Your lungs are the most important part of the floating equation. Without your lungs your body (and mine) would sink like a rock. I’ll demonstrate that for you in a bit… 


Fat also floats. Fat has a lower sp gr than water. So the more fat you carry on your body, or rather the higher your body fat percentage is, the better your natural float-ability will be. 

What Sinks? 

Pretty much everything else in your (and my) body. 

Your bones, muscles, and other tissues found in the human body all sink. 

Bone density and lean muscle mass have a negative effect on your floatability. Athletes with heavier bones and more muscle will have a higher sp gr. The more muscularly dense you are, the higher you sp gr and the faster you will sink. 

In my 18 years of coaching I have worked with people that have an overall sp gr higher than 1.00. These people do not float naturally. People that sink do exist, but having a sp gr higher than 1.00 is less common than you think, and it’s likely you aren’t one of them. Of the thousands of athletes I’ve worked with, an overwhelming majority float when they are taught how

This guy floats – if he does, chances are, you will too! 

In my experience, 99.5% of people have a sp gr lower 

than 1.00 and float just fine. They just have to learn how.


How To Test Your Natural Floatability

I define natural floatability as the following: 

“How well your body floats as determined by your body composition.”

The simplest way to test your natural floatability is the Mushroom Float. 

The Mushroom Float Test 

Here are the steps to do a mushroom float:

  1. Do the test in the shallow end of the pool where you can stand.
  2. Take a deep breath in and then hold your breath.
  3. Lift your feet up off the floor and lower your head into the water
  4. Tuck your body into a ball, bring your knees up to your chest and hold your shins with your hands.
  5. When you need to breathe, stand up.
The test is very simple. But to get accurate results, it’s important 

that you perform the test correctly.


{1} Make sure you take a deep breath in. 

  • Fill up your lungs with air before you lift your feet and drop your head into the water.

{2} Relax your body as much as possible

  • You can swing the results by tensing up. Being tense suggests your floatability problem isn’t body composition, but rather mindset or fear.  

{3} Don’t wear heavy clothes. 

  • You will increase your sp gr by wearing board shorts or heavy clothes. Do this test in swim wear that isn’t baggy and doesn’t collect water. Time to bust out the budgy smuggler. 

The mushroom float is an unbiased test of your natural floatability as determined by your body composition. If you don’t fill your lungs, or you tense up or wear heavy clothing you swing the results. You aren’t testing your actual floatability. 

When this test is done correctly, 99.5% of people will float up to the surface within seconds of tucking up into a ball. 

My suggestion is that you try the Mushroom float test a few times. 

{1} First, prove that you actually float naturally. 

{2} Then, try exhaling while you are tucked up in the ball.  

When you exhale, you will probably sink. 

This is because your lungs are the only part of your body that actually floats. When you empty them, you sink. Your pelvis and femurs along with your glutes, quads and hamstrings make your legs very heavy. With no air in your lungs, your hips and legs pull your body under. 

There’s a reason that the mushroom float position keeps you up on the surface. Even though your legs are heavy, the tucked position changes the way forces that act on your body in the water. In the next section we’re going to take a look at those forces. 


Whether you fit into the 99.5% of people that float or the 0.5% that sink, one fact is constant for everyone. Your chest floats better than your legs. 

There are two forces responsible for your floaty chest and sinky legs.

{1} Buoyancy which is an upwards force. 

  • It supports or pushes up on your body and causes you to float 

{2} Gravity which is a downward force. 

  • It pulls down on your body and causes you to sink 

For you to float up on the surface of the water, the force of buoyancy must be greater than the force of gravity. 

Where Gravity > is greater than > Buoyancy; You Sink 😠

Where Buoyancy > is greater than > Gravity; You Float 😊 

The force of buoyancy is strongest around your chest. Because of your lungs, your chest has the lowest sp gr in your body. It is the least dense part of the body. This is where the force of buoyancy is strongest so we call the chest your center of buoyancy in the water  ^1

The force of gravity is strongest around your legs. Your legs have a higher sp gr than water, so the force of gravity is strongest through your legs. 

The way gravity acts on your body is a little weird. There isn’t one specific spot gravity pulls down through. Unlike buoyancy, which always pushes up through your lungs, the force of gravity can shift. The exact location gravity pulls through will move based on your body position. It generally pulls down through the area of your hips. But it can move up towards your belly button or down toward your knees, depending on how you are positioned. We call the point that gravity pulls down through the “center of gravity” ^2 

To float, the center of gravity and the center of buoyancy must align. Gravity must pull down in exactly the same line as buoyancy pushes up. With both forces pushing and pulling in the same place, you float level. 

This is why you float in the tuck of the mushroom float. During the mushroom float test, your legs sit underneath your lungs. So your center of gravity and center of buoyancy line up, one on top of the other. As a result you bob up to the surface. 

You don’t swim freestyle tucked in the mushroom float ball though. And this is where the sinking leg problem is born. 

As you stretch out your legs, the center of gravity begins to move down towards your feet. The further the center of gravity moves from the center of buoyancy, the faster your legs sink. 

The Dead Man’s Float 

We now know the center of buoyancy always pushes through your chest. And we learned that the center of gravity pull shifts as your body position changes. The Dead man’s float demonstrates this for us very nicely. 

Here are the steps to do a dead man’s float:

Phase 1:

{1} Begin with a mushroom float by 

{2} Taking a deep breath in and then hold your breath

{3} Lift your feet up off the floor and lower your head into the water

{4} Tuck your body into a ball, bring your knees up to your chest and hold your shins with your hands.

{5} Once you’ve floated up to the surface, release your legs and begin to extend them out behind you 

{6} Notice how your legs sink as you open up your body 

{7} When your legs have stopped sinking or you run out of breath, stand up

Phase 2: 

Repeat the test again. The second time you do it, as you extend your legs out behind you, stretch your arms out in front of you at the same time. 

What we see in Phase 1 of the dead man’s float is that your legs sink no matter what. The legs have a higher sp gr than your chest and the water so they sink faster!

Nearly every adult’s legs sink when doing the dead man’s float. 

Mine absolutely do! 

As you stretch out the center of gravity begins to move down towards your feet. The further the center of gravity moves from the center of buoyancy, the faster your legs sink. 

In all my years coaching, I’ve only had a handful of people that can float in this horizontal position (without kicking). The sp gr in their legs is lower than water and they are able to balance without moving. In most cases, these clients have been women and have had a higher body fat percentage at or around their hips. The extra fat decreases the sp gr in the legs which helps keep them level on the surface. 

Understanding that your center of gravity shifts is the key to your sinking leg problem. 

By changing your body position you can keep the center of gravity close to the center of buoyancy. The closer you keep these two points, the better you will balance. 

There are a few ways we can do this:

{1} Increase the amount of fat on your hips and thighs. 

Fat floats. If you have more fat around the most dense part of your body, you shift the center of gravity forward. 

If you carry a higher percentage of fat on your hips and thighs, you will balance better. While this is a potential solution, it isn’t practical for your triathlon performance.  It’s likely to negatively impact your bike and run times and effort.

{2} Kick more and kick harder. 

Every time one of your legs kick down there is an equal and opposite reaction pushing up. The upward push lifts your legs in line with your hips and head keeping your body balanced. 

If you have a good kick, you can keep your body balanced by increasing your kick tempo and the force of your kick. 

This is a highly effective solution. And it’s something you will want to learn and practice. But you have to manage how you kick. Too much kick will use a lot of energy that could be better spent elsewhere on race day. You need to use your legs in your freestyle, but you need to strike a balance. 

{3} Manipulate and control your body positions 

By changing your body position you can keep the center of gravity close to the center of buoyancy. The closer you keep these two points, the better you will balance. 

By making subtle adjustments to your body position you can change how well you balance. So fixing your sinking leg issue comes down to technique and how well you can find good body position. 

This is why I began this chapter by saying:

“Your body composition is not a limiter on your ability to swim fast. 

Your technique or positioning does.” 

If you get into the wrong positions you will sink. Using the wrong technique, you increase the distance between your center of gravity and center of buoyancy.  As that distance increases, your legs sink deeper. 

When you find the right technique, you will float. You will stop praying for a wetsuit legal swim. You’ll finally be able to throw away your damn buoyancy shorts. You will finally find efficiency and speed in the water. 

When you find the right technique, you will float and finally find efficiency and speed in the water. 

The rest of this guide is dedicated to explaining changes you can make to positively affect how well you float. 

I’ve identified and explained the 15 most common technique mistakes I see triathletes make and give you the exact steps to fix each one. Let’s get into it!  

* Page 235 

* The density and temperature of the water you are swimming in plays a small role. 

The sp gr of salt water is 1.025 (up from 1.00 in freshwater). Because salt water is more dense than freshwater, you will float higher in the ocean than you do in the pool.

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