“Drag Is the Enemy”: Gary Hall Sr. on Why Swimming Still Gets Its Physics Backwards

Gary Hall Sr. swam at three Olympic Games — 1968, 1972 and 1976 — held world records in butterfly, backstroke and freestyle, and was among the first swimmers to break four minutes in the 400m individual medley. After twenty-five years as an eye surgeon in Arizona, he made a complete pivot at fifty-five, moved to Florida, and took over The Race Club — the elite training centre his son Gary Hall Jr. had founded in Islamorada in 2003. Today, as its Technical Director and CEO, Gary Hall Sr. has built the most data-driven approach to swimming technique in the world. SwimmingDrive spoke to him about the physics of fast swimming, what the sport still gets wrong, and why drag — not propulsion — is the real battleground.

You’ve framed fast swimming around three laws — drag, propulsion, and inertia. Walk us through the framework.

I was a physics major before I went into medicine, always fascinated with it. When I got seriously into swimming, I realised there are four basic sciences that intersect in this sport.

One is physiology — the training of the swimmer, building the energy systems. Two is kinesiology — the biomechanics of how the arms and legs move to generate propulsion. Three is physics, which has been largely neglected. The physics of a swimmer is governed by Newtonian mechanics — or more precisely, fluid mechanics, which is a derivative of it. Newton’s three laws give us propulsion, drag, and inertia.

The fourth science — and this one is underestimated — is neuroscience. How the brain controls the body. All four of these determine how fast you’re going to swim. There’s nothing else I know of that interacts with this sport.

And of the three physical laws, you’ve consistently argued that drag matters more than propulsion. That’s counterintuitive for most coaches.

What makes swimming different from almost every other sport is the medium. Water is approximately eight hundred times denser than air. Whatever drag forces exist come into play at much lower speeds than they would in air. A jet has a screw sticking out of it — that’s a problem at seven hundred miles an hour. On a bicycle at thirty-five miles an hour, drag starts to matter. But in water? You push off a wall with your thumb sticking out and you’re already creating roughly eleven percent more drag than if the thumb was tucked in.

“Water is approximately eight hundred times denser than air.”

When I first invested in a propulsion drag meter from Italy — very expensive, it towed swimmers across the pool at fixed speeds — we tested everything we could think of. Thumb out, fingers splayed, head up, head down, feet hanging, relaxed core, tight core, air bubbles under the chest. Over fifty metres you get about two hundred drag measurements in ten seconds — a statistically significant number. That’s when I really became aware that drag is the enemy.

Can you give us a concrete example of drag versus propulsion in action?

Maggie McNeil. Olympic champion. We looked at her dolphin kick — she was kicking twenty-five yards in ten-point-two seconds with no fins, at a hundred and sixty kicks per minute. Exceptional. What I realised looking at her velocity meter data is that it wasn’t the propulsion side giving her the advantage. It was the drag side.

A typical swimmer loses thirty to forty percent of their speed from bending their knees in preparation for the next down kick. Maggie was losing nine percent. That’s the difference. When you watch a great underwater dolphin kicker, they move very smoothly — almost gliding. The athlete who isn’t good goes in a jerky, pulsing motion. Slowing down, speeding up, slowing down. They’re not taking advantage of inertia. It’s costing them more energy and they’re going slower.

In most strokes, propulsion matters — how strong you are, how much force you generate. But drag is really more important. You can’t eliminate it — the moment you move in water, you have drag. The question is how much you can reduce it.

You’ve said that swimming with great technique actually takes more work, not less. That’s not what most people expect to hear.

We tell every camper who comes to The Race Club: we’re going to make this sport harder for you, not easier. They look at us and say, what? I thought I was coming here to swim smarter and make it easier.

No. To swim with great technique takes more work. Full rotation, high elbow, driving from the core — none of that is easy. It’s demanding. The survival stroke — flat, arms churning, head up — is easier. It’ll get you across the Atlantic if your plane goes down. It will not make you fast.

“To swim with great technique takes more work. Full rotation, high elbow, driving from the core — none of that is easy. It’s demanding.”

The Race Club began as an elite training centre for post-graduate swimmers. How did it evolve into what it is today?

My son started The Race Club in 2003 with David Arluck — primarily to help post-graduate swimmers further their careers, give them a place to train at a high level and hopefully make the Olympic team or win a medal. We did that for four successive Olympic Games, training fifty-two Olympians.

At the end of my son’s career in 2008, he retired. We had a choice — continue as philanthropy, contributing money to help elite swimmers train, or start a business, taking what we’d learned and seeing if we could help other swimmers. By then all our coaches had taken other jobs. I was kind of the last man standing and decided I would become the coach.

But rather than coach a team or run a traditional club, I decided to focus on technique. I didn’t even realise at the time how important it is — I have much more appreciation for it today than I had then.

You trained under Doc Counsilman at Indiana — one of the great scientific minds swimming has produced. How much of what you teach today traces back to him?

Doc had a profound influence on me, not only as a swimmer but as the reason I went into coaching at all. He was always fascinated with science, always trying to understand why. That stayed with me through twenty-five years of medicine and followed me into the pool when I came back.

I’ve always felt — even with his great contributions — that swimming is a low-tech sport in a high-tech world. And it shouldn’t be. The technology is becoming less expensive, more available, more user-friendly. One of my passions today is to bring that technology into swimming and make it accessible to everyone, wherever they live.