Arrow-right Camera
The Spokesman-Review Newspaper
Spokane, Washington  Est. May 19, 1883

A Race Not Just A Race Myriad Factors Must Combine For Olympian To Run The 400

Jon Morgan Baltimore Sun

Poised liked a coiled spring on the starting blocks, the sprinter sets his feet, cocks his legs and stares down the track.

He is 5 feet 10 inches and 175 relatively fat-free pounds. He has the same set of organs and limbs as the rest of us. But years of training have imbued this hypothetical Olympic athlete with lungs that process oxygen more efficiently, a heart that is larger and pumps blood faster, and leg muscles that store more energy and tolerate more pain. Every system - respiration, circulation, how the runner thinks - has been refined.

The event? The 400-meter race.

The time? For the winner, the race should last fractionally less than 44 seconds.

This is an Olympic sprinter at work, much as he will be in Atlanta beginning July 20.

He is awaiting the starting gun. His pulse rate rises to 75 beats per minute - the rate of an average adult at rest - due to his warmup and the anxiety of 400 meters to come.

His temperature too, is up a degree or two above normal, another function of the warmup. He is taking in a little less than a liter of air with each breath, at a fairly leisurely rate of 12 breaths per minute.

This changes almost instantly when the starting gun is fired. The runner’s neurological system executes a series of muscle contractions that raises him from a crouch and launches him off the blocks and down the track. He goes from a standstill to full exertion in a few powerful strides.

An electro-chemical network of transmitters throughout his body rushes messages back and forth from his brain to his legs, attempting to adjust every step to maximize speed while taking into account changes in wind, balance, velocity and inertia.

The sudden acceleration outstrips his body’s ability to generate energy through oxygen, the aerobic process that powers every weekend jogger. His system switches over to a cache of reserves. These are non-oxygen - “anaerobic” - fuels, high-energy molecules stashed in the muscles and called adenosine triphosphate, or ATP, and creatine phosphate, or CP.

This system works well for short bursts, propelling him through the first 100 meters of the race. But it doesn’t last: 10 seconds into the event, the ATP and CP wells are dry.

The runner’s body then turns to its second anaerobic energy source, glycolysis, biochemical reactions that convert glucose stored in his muscles into usable energy and begin to replenish the supplies of ATP.

At about 200 meters, or 20 seconds into the race, glycolysis is working smoothly. The runner is at his peak speed, more than 25 miles per hour. His arms are swinging and his knees are pumping up and down like pistons, powered by overlapping muscles that alternately contract and relax, drawing fuel from their own microscopic energy depots.

His heart is beating 180 times per minute; during each contraction the pressure of his blood against artery walls rises to 200 millimeters of mercury, nearly twice his rate at rest. Blood is coursing through his veins at 20 liters per minute, four times faster than half a minute ago.

His neurological system is taking full advantage: It has shut a series of valves in his blood vessels to focus the supply on his heart, brain and muscles. Organs unnecessary for the race, such as his stomach, are temporarily shut off.

He has become literally a running machine.

But this full-throttle pace can only be maintained for 50 to 100 meters, even by this elite athlete. Glycolysis generates an unwanted byproduct: lactic acid. The acid, which produces the “burning” sensation familiar to weekend joggers, is rich in hydrogen ions and inhibits the contraction of muscles, slowing the runner down.

The acid stems from a design limitation. We all are built chiefly for aerobic exertion, not anaerobic. Lactic acid prevents us from exceeding our limits, at which point our legs would simply stop and muscles could be damaged.

By training at peak output, sprinters develop a tolerance for the pain. But this only delays the effects. Lactic acid eventually slows even the world’s fastest men. So the runner slows over the second half of the race to a speed 10 or 20 percent off his peak.

Because most of the energy his body is producing is in the form of useless heat - humans only use about 25 percent of the energy they create - his muscles are now several degrees above normal temperature.

To cool him, sweat glands are drawing water from his blood and passing it through the skin where it evaporates, absorbing heat as it changes from a liquid into a gas. His breathing is now deep and fast, his chest heaving. He is inhaling air at a rate of 150 liters per minute, 15 times the rate at rest.

But that air is largely superfluous to the immediate demands of the race. Because he is drawing upon stored energy, the rapid processing of oxygen goes largely unused, other than some that finds its way to the heart and brain. Theoretically, he could - like a short-distance swimmer - be holding his breath.

But his body does not know how long it will be running and is relying again on its aerobic system. Though slow to start, the aerobic system is easier to sustain over long periods. A marathon runner depends on it for more than 95 percent of his energy during a race; a sprinter will only use it for about 5 percent of his energy needs.

With the runner at the 350-meter mark, the extra oxygen begins to contribute. Rushed to the muscles by the rapidly beating heart, it chemically breaks down carbohydrates, fats and proteins. Such molecule splitting releases energy, which the muscles swiftly consume.

Crossing the finish line, the runner’s body has barely begun the shift to aerobic energy, but the appearance of oxygen has allowed the ATP and CP to regenerate.

As the runner walks to cool down, his heart and respiration rates gradually return to normal; his regular blood flow has already returned to all organs. Lactic acid is flushed to the liver where it is metabolized; the burning in his legs subsides.