Marathoners are the NASCAR racers of running, trying to keep their radiators from boiling over during 42 kilometers and more than two hours on the road. Sprinters don’t have the same worries about heat and humidity. They are dragsters, generating massive power and searing speed then pulling the parachute in seconds.

The men’s and women’s Olympic marathons will be held in Sapporo, some 800 kilometers north of Tokyo, to escape the smothering blanket that is Tokyo’s average August weather: a high of 31 degrees Celsius, low of 25; humidity at 73%; a “feels-like” temperature or heat index of 38.5 degrees.

But when the men’s and women’s sprints begin Friday, most competitors will embrace the hot weather, reveling in conditions that Carl Lewis, the nine-time Olympic champion sprinter and long jumper, calls “the Caribbean without the breeze.”

“Ninety-nine percent of sprinters love it, especially Americans,” said Lewis, now an assistant track and field coach at the University of Houston. He might have added, so do Jamaicans, the world’s other dominant sprinters.

Historically, top performances from the 100 meters to the 1,500 meters, and field events such as the long jump have mostly come in July and August, the hottest time of the year, when major international competitions are held.

If the past is any guide, some extraordinary results could occur in Tokyo, perhaps especially in sprinting and jumping performances enhanced by many factors, including rapid muscle contraction in the heat and, to a lesser extent, the physics of reduced air resistance.

“You need those muscles to fire at a rapid rate,” said Rai Benjamin, an American hurdler and sprinter who is a gold medal candidate in the men’s 400-meter hurdles. “When you’re cold and stiff, it makes for you to be more cautious. Although sometimes you don’t want to be, subconsciously it’s in the back of your mind, ‘OK, it’s cold out here I don’t want to hurt myself.’”

There is another weather-related phenomenon, widely discussed but little understood, in the track and field world: A handful of astonishing record performances, in Tokyo and elsewhere over the past half-century, occurred just before or after stormy weather.

“If it rains right before a race, I’m going to run fast,” said Noah Lyles of the United States, the Olympic favorite in the men’s 200 meters.

Coincidence? A correlation between performance and stormy weather, when the atmosphere becomes electrically charged with molecules known as negative ions? No one knows with any certainty.

Purported cardiovascular, respiratory, psychological and cognitive benefits of exposure to negative ions have been a matter of scientific debate for a century. Enthusiasts sometimes call them “vitamins of the air.” Research has been inconsistent. Some skeptics dismiss the supposed benefits as pseudoscience.

“If someone would come up with actual information, that would be interesting,” said Lance Brauman, who coaches Lyles and other Olympic favorites in Clermont, Florida, in the Orlando area. “These guys are neuromuscular machines. Anything that would stimulate the electrical system of the body would theoretically help.”

Performance advantages for sprinters in hotter weather are relatively small, gains of 1% to 2%, scientists say. Other factors like altitude, biomechanics and doping are considered to have a bigger impact. The outcome of races in Tokyo could depend on a number of influences: top runners competing head-to-head; advanced shoe technology; the absence of energy from spectators who have been barred by pandemic-related regulations; reaction to the starting gun; the length and frequency of strides; the amount of force exerted into the ground; the hardness or springiness of the track; and the speed and direction of the wind.

Not all athletes respond to heat the same way. But it will play a role. And in sprinting and jumping events, that can be decided by a hundredth of a second or a quarter of an inch, tiny benefits might help make the difference between winning a gold medal or no medal at all.

“That could be the small margin of performance that will make you faster and put you on the podium,” said Olivier Girard, an exercise physiologist at the University of Western Australia who studies sprinting and heat. “Tokyo is supposed to be the hottest Olympics in history, so surely we might see something interesting.”

Rai Benjamin running at the Olympic trials in June. | KIRBY LEE / USA TODAY / VIA REUTERS
Rai Benjamin running at the Olympic trials in June. | KIRBY LEE / USA TODAY / VIA REUTERS

At the last major international track and field competition held in Tokyo, the 1991 world championships, Mike Powell set a world record of 8.95 meters in the long jump that still stands. Lewis, who engaged Powell in an epic jumping battle, also set a world record there of 9.86 seconds at 100 meters. That record has been broken repeatedly since then but remains a landmark. For the first time, six sprinters ran below 10 seconds in the same race.

Hotter temperatures help boost the short-term power output needed for world-class sprinting. There is probably an optimal temperature range in skeletal muscles for unleashing the energy-producing molecule in cells known as adenosine triphosphate; for activating motor nerves and for quicker muscle contractions that increase the rate or frequency of a sprinter’s strides, scientists say.

“Those slightly warmer temperatures like 80-90 degrees (27-32 degrees Celsius) are going to be much better than 60-70 degrees (16-21 degrees Celsius) for that,” said Robert Chapman, an environmental physiologist at Indiana University and the director of sports science and medicine for USA Track and Field, the national governing body.

The top American sprinters, and many international stars, train in the hot weather of Florida, Texas and California. Jamaica has a similar climate for speed. Heat serves as a passive warm-up device for muscles, so it does not take as long to get them limber with pre-race exercises, athletes say.

“When it’s warmer weather, I’m able to focus firmly on my race plan and tactics,” said Trayvon Bromell of the United States, a gold medal favorite in the men’s 100 meters. “When it’s cooler, I feel that my mind drifts to making sure my body is warmer first. It leads me to build a different pre-race plan.”

Hot, humid air is also less dense than colder air and slightly reduces drag. This helps explain baseballs traveling farther when hit in hotter weather. As the temperature rises, gas molecules in the air move faster and farther apart, lowering resistance to moving objects. And contrary to what many people think, humid air is lighter, not heavier, than dry air because water vapor displaces weightier nitrogen and oxygen molecules.

In places near sea level, like Tokyo, the combination of heat and humidity should result in about a 3% reduction in air density (as compared to a 25% difference between sea level and the 2,225-meter altitude in Mexico City, the site of the 1968 Summer Olympics), Chapman said.

“Would a 1% to 3% change in air density end up affecting performance? It has to,” he said. “It’s just a question of what’s the magnitude and how does that magnitude compare to the 57 other things that can influence an athlete’s performance from mental to physical to everything else?”

The main concerns for sprinters in Tokyo will be remaining properly hydrated and rested; staying out of the sun as much as possible and expending as little energy as necessary to advance through the preliminary rounds.

They might also want to pray for rain.

At the 1968 Olympics, Bob Beamon’s startling long jump, which broke the existing record by more than 60 centimeters, came just before a storm. So did Wyomia Tyus’ world record in the women’s 100 meters. Clearly, altitude influenced those performances. But Powell’s jump that broke Beamon’s record in 1991 also came before a storm, in Tokyo, which is only 9 meters above sea level.

Usain Bolt of Jamaica first broke the world record in the 100 meters following a rainstorm at a meet in New York before the 2008 Beijing Olympics. A light rain followed the setting of his current world record, 9.58 seconds, at the 2009 world championships in Berlin, observers said.

“My focus was always on executing the race and I didn’t care too much about the weather,” Bolt said.

In the 1970s, Soviet and East German scientists found no positive effect of negative ions on physical performance, said Alfred Nimmerichter, an Austrian exercise physiologist. His own 2014 research on negative ions and cycling found no increase in oxygen consumption.

“From the gut, I would say the performance versus storm relationship is coincidental, at least from a physiological standpoint,” Nimmerichter said.

Other research has variously suggested that exposure to negative ions could elevate mood and alertness, reduce stress and stimulate the fight-or-flight response by increasing the heart rate and blood flow to the muscles.

Skepticism remains. Lewis recalled that he was long-jumping in Indianapolis in the 1980s during stormy weather when a man excitedly approached his father and said, “Oh my God. He’s got to jump again. The ions are right. I was in Mexico City and it was just like this for Beamon.”

And what did his father tell the man?

“Dude, seriously, get out of my face.”

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