How the US women's soccer team trained to beat the heat in Tokyo

Millions of eyes around the world are on Tokyo as athletes who have spent years, and even decades, training to battle each other -- and the heat.

As the U.S. women's soccer team gears up for its next big match, there is one man cheering them on with insider knowledge of just how hard women like Megan Rapinoe, Becky Sauerbrunn and Alex Morgan trained, not just to perfect their soccer skills, but to prepare for the heat and humidity that many feared would materialize in Tokyo at this time of year.

Dr. Robert Huggins is president of research and athlete performance and safety of the Korey Stringer Institute at the University of Connecticut. He was part of a team that helped get the U.S. women's soccer players ready to play their best in Tokyo.

Summers in Tokyo are notoriously warm and humid. Japan has faced criticism in recent days for not accurately describing the severity of summertime heat, with officials reportedly calling the weather "mild" and "ideal" during the bidding process.

The average high in Tokyo for this time of year is 84. Highs this year during the first week of the Olympics have been in the low to mid-90s, according to AccuWeather data, with the highest temp being 94. During the first week of the Games, athletes experienced temperatures in the mid- to upper 90s with about 80% humidity. AccuWeather RealFeel® Temperatures have reached into the upper 90s.

United States' Megan Rapinoe, right, and Australia's Ellie Carpenter battle for the ball during a women's soccer match at the 2020 Summer Olympics, Tuesday, July 27, 2021, in Kashima, Japan. (AP Photo/Fernando Vergara)

The stifling heat and humidity prompted some athletes, including world No. 1 tennis player Novak Djokovic, who described the humidity as "brutal," to request event times be moved to cooler hours. The hot weather came as no surprise to Huggins.

"What we did was we anticipated that Tokyo, that Japan, was going to be the hottest Olympics and record based on the last years of rising temperatures and looking at historical data of the previous Olympics," Huggins said. "So we knew it was going to be hot."

Huggins told AccuWeather his team studied historical weather records in Japan and explained to the coaches and soccer players how that would affect the players' athletic performance in Tokyo.

Dr. Robert Huggins, President of Research and Athlete Performance and Safety, Korey Stringer Institute, Univ. of Connecticut.

"If you've ever exercised in Orlando or Gainesville, Florida, in the middle of the day, or middle of the afternoon, this is what it's going to feel like," Huggins said he told the team.

"That kind of really hit home for many of them and they said, 'What can we do to make sure at the end of the second half of our game that we're still able to have the intensity that we need, the heart rate that we need, that core temps aren't too high, that we can still play our game and get to that ball and run?' So we worked with them to optimize that."

Heat acclimatization is the improvement in heat tolerance that comes from gradually increasing the intensity or duration of work performed in a hot setting. Huggins says the best way to acclimatize to the heat is to increase the workload performed in high temperatures over a period of weeks.

He advises exposing yourself to the heat for 60 to 90 minutes over a one-day to 14-day period. But Huggins warns those trying to acclimatize to do so carefully based on your level of physical fitness, so you don't end up with heatstroke. Elite Olympic athletes are already in excellent shape so their heat training involved players' heat exposures in the months leading up to the games being carefully planned.

"What we did is we looked at the level of heat exposure that each athlete was going to be having in their practices with their professional teams or games with their professional teams and then we essentially worked with them to plan their exposures when they went to their training camp in Texas," Huggins explained.

Team USA players are at the top of their game thanks to the intense planning that also involved spending time in heat laboratories around the country as well as labs at the Korey Stringer Institute, which Huggins said helped prepare them for the specific weather conditions in Japan.

The MISSION Heat Lab is an environmental chamber capable of precisely controlling ambient temperature from 40 degrees Fahrenheit to 110 degrees Fahrenheit, humidity from 20% to 90% and radiant heat simulating from full cloud cover to unobstructed sun. The facility can simulate the variety of thermal environments faced by athletes.

Huggins explained that athletes came to the lab and worked on acclimatization several times. "We had additional heat sessions in our labs that were purposeful to induce the physiological adaptations that come with providing more heat exposure to an individual all before them going to Japan," he said.

Calling the women phenomenal athletes, Huggins said the women are geared for gold. He's excitedly following the team's progress in Tokyo.

"It was an honor to work with them, it was definitely one of my top three experiences professionally in my career," Huggins told AccuWeather. "I hope that they outlast their opponents from a physical performance perspective that would then allow their skills to continue to shine late in the game so that they can finish strong and bring it home."

The United States will face Concacaf rival Canada at 4 a.m. Eastern time Monday in the Olympic semifinals after the Americans defeated the Netherlands on Friday, 4-2 on penalties after a 2-2 draw.

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