Does Fat Make You Faster Swimmer?

Every sport has its enduring, but totally groundless myths. When it comes to swimming, the all-time champ is probably the one about body fat as an indispensable aid to doing well.

While it’s mostly the sinewy triathletes and runners at my swim camps who have fallen under this fictitious spell, it could be any ectomorphic would-be swimmer. “Thanks for trying to turn me into a good swimmer. But, I don’t have enough buoyancy to do anything except sink like a stone,” goes the lament.

But you do! And this should convince you: Tom Dolan, once America’s best hope for Olympic medals in distance freestyle and a world record holder in the 400-meter individual medley, has a razor-thin three percent body fat. Floating is obviously not the issue.

Yes, swimmers, by and large, are heavier than runners, mainly due to upper-body development. Watch a 10K road race and you’ll see that those who lead the way to the finish line are often lucky to cast a shadow.

Watch a Masters swim meet or any open water swim race and the best swimmers will also be lean and trim. But a glance back into the pack will show a whole range of body types from rails to fireplugs with Clydesdale types well represented and reasonably successful.

But equating good swimming with a genetically endowed body type is taking the easy way out. And it’s backward besides. Swimmers use a lot more upper body strength than runners, so hard swim workouts eventually build a big chest and shoulders. But a solid upper body doesn’t predict success as much as result from the work that produced it.

“No matter how fit I’ve gotten myself, there’s always some overweight guy in the next lane swimming circles around me,” the runners snap back. Good for him. He deserves more credit than you’re giving him. Speed has nothing to do with any buoyancy that extra adipose may produce. In fact, heavier people can be grateful for just one thing: that they’re swimming, not running.

In the water, they’re less penalized for carrying added poundage since body weight is only 10 percent what it is on land. In a road race, an extra 20 pounds feels like a knapsack full of bricks; in an open water or pool swim, you hardly notice it.

Make no mistake, however: Top swim coaches are just as interested in lean, strong athletes as coaches in any other sport. And at the elite level, swimmers are, in fact, at least as trim as athletes in other sports, even though their developed torsos make them look bigger. It’s the recreational level that breeds confusion, since athletes can be stars in local Masters competition with shapes that are, let us say, more rounded than sculptured.

But, they’re fighting physics to accomplish that. True, fat adds buoyancy and heavier people can bob around as if they were rafts. But fast swimming is not bobbing. It’s moving through the water, and a streamlined body always moves easier.

Drag, the resistance of a fluid to a body moving through it, has a greater effect on how fast you swim than anything else you can control. The larger the body, the greater the drag. So excess fat, while increasing buoyancy a bit, also requires more energy and power to move it.

Also, fat is no friend of your VO2 max. The higher that value, which measures how much oxygen your muscles can use, the greater your capacity to do work, like swimming. Fat doesn’t burn oxygen, so the more of it you have in relation to muscle, which does burn oxygen, the punier your VO2 max becomes. Who cares if you float like a cork if your muscles can’t do much work?

So how do those fast swimmers get fast? Body position, which surprisingly has little to do with how you float. Lean swimmers like Tom Dolan, not to mention the heavies in the lane next to you, maintain efficient body angles because they have good balance. Like everyone else, they sink in the water to some degree. Their secret is to sink evenly, rather than wallowing like a ship whose cargo has slid to the stern.

Our body composition works against us in a different way than we suspect. We’re built to be balanced and stable on land with lots of mass and length below the waist and mostly volume above it. We tend to sink at the hips and legs, while we’re very buoyant between the armpits. A poorly balanced swimmer spends lots of energy dragging that nether region along like an anchor.

A well balanced swimmer knows how to reverse this, pressing the more buoyant forward part of the body deeper into the water, raising the less buoyant part. No one’s body bobs to the surface like a cork. Check also Kosuke Kitajima’s story.

Whether you can count your ribs, or haven’t seen them in years, has nothing to with your future in the water. Chin up, runners and triathletes, you have all the body fat you’ll ever need to swim well. In fact, you’d better hope that meaty barge who’s lapped you twice in the next lane doesn’t lose some weight. If he knows a thing or two about balance, matters could get much worse.

3 comment on “Does Fat Make You Faster Swimmer?

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