WHAT’S FAT GOT TO DO WITH FAST?

It makes floating easier, but does body fat make you faster?

By Terry Laughlin

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've fallen under this fiction's discouraging spell, it could be any ectomorphic would-be swimmer. "Turn me into a good swimmer? Thanks for trying. I don't have enough buoyancy to do anything except sink like a stone," goes the lament.

Oh yes they do. And they're shocked when I hit them with my convincer: Tom Dolan, one of America's top distance freestylers and a world record holder in the 400-meter individual medley, has a razor-thin 3- percent body fat. The ability to float is obviously not the key to fast swimming.

Swimmers, by and large, are heavier than runners. 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, on the other hand, and the best swimmers will display a whole range of body types from rails to fireplugs, with Clydesdale types well represented and frequently very successful as well.

But equating good swimming with a genetically endowed body type is taking the easy way out. And it's backwards 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, so much as result from the work that produced it.

"OK, then. If padding doesn't matter, what about those speedy spare tires I see in the pool?" the runners snap back. "No matter how fit I've gotten myself, there's always some overweight guy in the next lane swimming circles around me." Good for him. He deserves more credit than you're giving. 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.

Good thing, too, since swimming is an appetite builder. Runners usually don't feel much like eating for an hour or so after a workout. But food is often top of mind for a swimmer climbing out of the pool. That’s because submerging yourself for an hour in water that's usually 15 to 20 degrees cooler than your body sets the "more-fuel" alarms off so replacement heat can be produced.

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, just as trim as athletes in other sports, even though their developed torsos make them look bigger. It's observing swimmers at the recreational level that breeds confusion, since athletes can be stars in Masters competition with shapes that are, let us say, more rounded than sculpted.

But heavy swimming stars are fighting physics to accomplish what they do. 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 than an unstreamlined body, no matter how lean. 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 your body, the greater the drag, so excess fat, while increasing buoyancy a bit, also requires more energy and power to move it.

And 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 of all shapes 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 unexpected ways. We're built to be balanced and stable on land with lots of mass and length below the waist, mostly volume above it. So where do we sink? Right: 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 process, by pressing the more buoyant forward part of the body deeper into the water, raising the less buoyant rear part. Your front half rides a bit lower, your rear half much higher, sacrificing buoyancy a bit in one place to improve it dramatically in another. No one's body bobs to the surface like a cork. But smart swimmers make their bodies sink more evenly so that no part drags deeper than another.

So whether you can count your ribs, or haven't seen them in years, has nothing to do 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.