Think 61 Degrees is Nice? Ask an Open Water Swimmer

PHOENIX, Arizona, September 11. AFTER spending my Sunday morning off the coast of Tiburon, California, watching packs of athletes sprint across the open water from Angel Island to the docks of Tiburon at the 2012 RCP Tiburon Mile, I began to wonder, what really goes into an open water swim?

Open water swimming has gained popularity in recent years, partly because the sport is promoted as an alternative to the monotony of “chasing black lines” in a swimming pool. But there is an added element of mental toughness required for a swimmer to brave currents, cold water, poor visibility and hundreds of bodies fighting for prime positioning.

I managed a spot on the lead boat next to a crew of cameramen. From my vantage point, I could almost see the goose bumps on the competing athletes. The boat driver cut the engine about fifty meters from the rugged beaches of Angel Island, and I watched as hundreds of athletes filed from the ferries that transported them from Tiburon, preparing to plunge into the chilly San Francisco Bay waters.

Swimmers hardly look forward to hopping into a race temperature pool (about 78 degrees Fahrenheit), so the 61-degree waters of the Bay take extra physical and mental preparation. It should be noted that 61 degrees is about the warmest an open water swimmer can expect in the Bay Area.

Swimmers in short briefs jumped up and down, hitting their arms, legs, and chest to stimulate blood flow. Others bent down to the waters edge, splashing their skin. Several brave souls swam out several yards into the water, “warming-up” to minimize the initial cold shock. The elite group, racing for the $10,000 grand prize, looked ready for another day at the pool: swim caps, goggles, and practice suits. Farther back, the pack was dotted with black wet suits, a division of its own.

Physiologically, the human body struggles to find its equilibrium when submerged into cold water. If you wade into a body of water and stand perfectly still, your body loses heat slower than if you are jumping around, trying to shake off the biting feeling of the water.

This is because the human body is losing heat through a single medium, convection, when it is perfectly still. The blood vessels at the skin's surface are releasing heat into the water, trying to find a balance between the 61-degree water temperature and the 98-degree body temperature. The effect of this exchange is two-fold: the water immediately surrounding the skin is warmed, and the body is cooled.

But add in the fact that these athletes are sprinting a mile across of open water, and it becomes a whole different ball game. Because water is rushing past, and blood vessels are constantly pumping oxygen and blood to the swimmer's straining muscles, the body cannot — for lack of a better phrase — “slow down” to regulate heat loss. The motion adds conductive heat loss into the equation, upping the total amount of heat loss significantly.

One way to look at this phenomenon is to compare it to wind chill. The weatherman may report outside temperatures at 45-degrees, but with 20-mile-per-hour biting winds added in, I'd grab a heavier coat!

When the gun went off to signal the start of the RCP Tiburon Mile, and the athletes rushed into the water, most were thinking about the perfect positioning to pull away from the pack. But inside, their bodies were fighting a heated battle.

I rocked with the boat as it eased over the low swells. Four or five elite athletes quickly pulled away, hugging the coastline. About 500 meters into the race, I noticed a shift in their positions. The pack took on a V-shape, athletes strategically positioning themselves at the knees of their nearest competitor. Welcome to another element of open water racing: position.

An athlete conserves a considerable amount of energy when their position allows them to draft off the lead swimmer. Spectators can see this in pool races when a swimmer “hugs” the lane line, riding the wake of the front contender. Some people call it cheating, others call it strategy. But in the world of open water swimming, a pack leader expects others to capitalize on their forward surge.

There are a number of articles out detailing the most effective ways to draft during open water races. The main point is that position is everything. The front swimmer is displacing the most water, creating a bow wave that other swimmers can ride. It's almost like surfing — but just with a really, really small wave. By tapping into the energy the front swimmer is using to cut through fresh water, the trailing swimmers can conserve their own energy. Then they just have to fight over the bow wave when it comes time to make their move.

Since the RCP Tiburon is only a mile, the period for drafting was far eclipsed by the “break away” time. Individual swimmers positioned themselves several yards away from the pack, lifting their heads forward to look at positioning. Volunteers on surf boards weaved in and out, alert to people straying too far off course. Water churned, and the swimmers rapidly progressed to the finish line as our boat took a sharp cut right, racing to the docks to beat the athletes to the tape.

After the race, I chatted with a few of the athletes. Some of them had never swum an open water race before; some of them had competed in them for years. The general consensus was that the water was cold. One athlete said his biggest obstacle was gauging his speed because his blood vessels constricted so much; he ended up losing feeling in his limbs. It should be mentioned that it was his first time venturing outside of the pool.

All I have to say is, I have a newfound respect for open water swimmers. Not only do they have to know the mechanics of swimming, they have to deal with the hazards that come in an open body of water. And the next time I jump into a pool, I'll be acutely aware that although the water may be chilly, it's nowhere near as bad as the water off the San Francisco Bay.

Written and Posted by Shoshanna Rutemiller, who would like to thank Robert C. Placak, Christine Wilson, Tod and Cathy Spieker and the rest of the volunteers at the RCP Tiburon Mile and Sprint Classic for hosting a wonderful weekend of events.


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