Anyone who has spent the morning hours at Yarkon Park in the months of June in recent years may have encountered a strange sight: a large team of physiologists and medical personnel chasing athletes in the park, taking blood samples and various measurements from them while running. The goal: to check if the marathon runners who are going to represent Israel in the Olympic Games in Paris this coming July perform well in difficult climatic conditions. And those who get a low score in the tests - may be forced to watch their friends compete from their couch at home.

Competitive sports are facing forced changes. The climate crisis, which brings with it extreme weather events, means that athletes are forced to compete in much more difficult conditions than those for which they were prepared. In order to win the competition, good physiological data, mental strength, and training are no longer enough: the weather conditions must also be taken into account, and the body must be adapted to it in advance. Specifically in Israel, they were among the first in the world to identify the trend and to change the training programs.

"In 2018, two years before the Tokyo Games, we established a climate forum at the Olympic Committee to deal with the hot weather conditions we assumed would be there, and to find better ways to deal with exertion in the heat," says Muli Epstein, a physiologist, the scientific director of the Israeli Olympic Committee, and the director of Podium - The National Program for Coaches.

"We wanted to give the coaches and the professional staff tools to make it easier for the athletes in competitions to use different means of cooling. Today we know that the protocols we developed help athletes improve their achievements."

Did you recognize that the extreme heat conditions affect the athletes?

"The conditions are getting more difficult every year. In Tokyo 2020, the marathon was moved from Tokyo to Sapporo, and for the first time, the marathon was not held in the city where all the games were held. They thought it would be more pleasant there, and in the end, it was worse there. The World Cup in Qatar - a country that hosts sports events thanks to its big money and despite the climatic conditions - was moved to November-December because it was impossible to hold it at 50 degrees Celsius in June and July. They also hosted the World Championships in Athletics and moved it from the summer to October, then the marathon in the women's and men's races started at midnight because they were looking for the coolest hours. These are hours when athletes sleep; they are not used to running at this time, and even then it was 30 degrees and 70% humidity, and close to 40% of the runners dropped out from the race. The male runners fell on a day with better conditions, and there only about 20% dropped out (compared to about 10% who drop out in a race held under normal conditions). It was crazy: they run slowly, like in a soup. It's hot, wet, and terrible."

What are the optimal conditions for marathon runners?

"Unlike short runs, the ideal conditions for running a marathon are around 10 degrees Celsius. It's an effort that lasts two hours or more, with a very high increase in metabolic heat, and when you combine the two things with hostile environmental conditions of heat stress it may result in a disaster. We clearly see that the results of the runners in the summer Olympic Games are whole minutes slower than those obtained in the autumn or spring competitions. In hot conditions, all runners should run much more carefully, slowly, and patiently. You can't run fast in such hostile conditions. The body could literally break down under such high heat load conditions."

How do the athletes react to these conditions?

"The World Athletics Federation tested it in Doha. The athletes swallowed a pill called e-Celsius, which transmits the temperature of the body's core for 24 hours; And the skin temperature was measured with the help of thermal cameras, and the results were compared to the performance indicators. The runners who had the biggest difference between the core temperature and the skin temperature - survived the best. If the core temperature reaches 38 degrees Celsius and the skin temperature is maintained at 34 degrees, there is a difference of 4 degrees. The heat is emitted through the skin, which means they cooled themselves better. We understand from this that athletes who were used to dealing with heat achieved better results. We also realized that it is important to cool the exposed areas of the skin: the neck, arms, and shoulders. That's why we tell the athletes to cool these parts of the body during breaks with a towel dipped in ice water."

A deadly cocktail of heat, humidity, and accelerated physical activity overcame Czech runner Anna Struzhkova two years ago at the peak of her career: in a cross-country race in Chiang Mai, Thailand, where she succumbed to heat stroke and lost consciousness before the finish line. "Every step became more difficult, the body weakened, I could not control my legs," she said, and admitted that she did not correctly assess the extreme conditions of the race. Her story is particularly relevant ahead of the Olympic Games that will open in Paris in July at the height of summer, where athletes may once again compete in extreme conditions for which they were not prepared.

According to a study published in June in the International Journal of Physiology and Sports, physical activity in the heat damages the athletes' achievements, but preparation in advance can help. For example, at the World Athletics Championships held in Doha in 2019, athletes who performed even a short preparation of practicing physical activity under extreme conditions managed to achieve more impressive achievements than their colleagues, who also needed more medical assistance.

Epstein and the Israeli Olympic Committee embarked on a journey to acclimate the athletes in 2018. They mapped the disciplines and found those most at risk are sailing, long runs, cycling, and triathlon, and decided to invest a focused effort in them. "We started working with the unions and the professionals and used the summer before the games to practice preparing for the heat conditions: acclimatization to the heat, cooling strategies, and other planning of the training process and preparation for the competition."

How have the preparations changed?

"All the years of preparation for the target event, World Championships, or Olympic Games, of the marathon runners, took place in Ethiopia. The problem is that in Ethiopia at this time, it is very cold, between 14-16 degrees, then you have to get to the competition which takes place at 28 degrees on average. We saw that the athletes performed very poorly after coming from there. They had weak results and dropped out.

"Before Tokyo, we realized that a marathon in hot conditions is a completely different marathon, and we changed the preparation pattern. Now instead of going to Ethiopia, we are preparing in the town of Baster in Italy, in high altitude and hot conditions. The training plans were changed, as well as the planning of the run itself: the training sessions were shortened, and the intensity of the training was changed.

"Thanks to this, the Israeli marathon runners recorded fantastic successes in the major marathons. In Tokyo, the most senior Israeli runner - Maru Tefri, a runner of Ethiopian origin who grew up in Israel - finished in 13th place, our greatest achievement up to that time, and in fact, the athlete of Ethiopian origin who finished the Olympic marathon the highest. The Ethiopian representatives themselves finished after him or collapsed and dropped out. Even the fastest runners in the world collapsed (apart from the runner who won the marathon, Eliud Kipchoge). They probably did not prepare for the marathon in such heat.

After Tokyo, we had success at the 2022 World Championships in Eugene, Oregon. Then two Israeli athletes won the silver and bronze medals at the European Championships in Munich; And the Israeli team in the marathon, as a team, won gold. Last year at the World Championships in Budapest, Maru Tefri won the silver medal, and Lonah Chemtai Salpeter finished in fourth place. There is already internalization, learning, thinking, and application of the climate matter in the entire planning process."

How do you know that the athletes are ready to face running in difficult heat conditions?

"The Athletics Association conducts a physiological fitness test for heat conditions for the marathon runners about six weeks before the competition. In recent years, it has taken place in Yarkon Park in June: a 30-kilometer run when it is already hot and humid. A whole team of physiologists, medical personnel, and nutritionists arrives in the field. They analyze how the pulse behaves when the body heats up, measure how much fluid they consumed, what their perspiration rate is per hour, and even take blood samples while running to measure lactate, which reflects the intensity of the effort and the athlete's ability to regulate their energy use.

"Since this is done long enough before the competition, we know who is in excellent condition, who is not acclimatized enough, and who needs to be worked less because the physiological indicators are not yet in a state of acclimatization. The process helps us understand who can be launched into the final preparation process before the competition. It also helps the Athletics Association to select the runners for the Olympic Games. We have more athletes who have set the Olympic criterion than there are places available, and the association has to decide who the three with the highest competitive potential are. If a warning light comes on in the heat check - that's a problem."

How do you cool down the athletes during the games and allow them to maximize their achievements in the competition?

"In sailing, we have special cooling vests that we order according to the measurements of the athletes. You freeze the vest in ice coolers, and wear it between sailings on the trainer’s boat, and it lowers the temperature of the body.

"In the marathon, the team standing along the route prepares for the runners hats that have ice cubes in them or ones dipped in ice water. We know that there is an accumulation of heat in the head area and when you cool this area, it helps. In the race, clothes and sponges with cold water are handed out to cool the body.

"Cyclists can use cooling vests before the start to lower their body temperature. Their advantage is that they move quickly against the wind and this helps to lower the body temperature. You can also open the cycling suit to enjoy more efficient heat dissipation. In addition, make sure to drink enough, Riding with sunglasses and wearing a helmet that allows ventilation."

The question now is how do we prepare for the Olympic Games in Paris? The Israeli delegation is expected to include 85 athletes, some of whom will compete in the Olympics for the first time.

"In all sports there is already an understanding and recognition of the connection between climate and achievements," says Epstein. "We asked the associations to come to the steering committee of the Olympic Committee to present their preparation procedure for the games from the climatic aspect: how they ensure acclimatization of the body, where you hold the preparation near the games and what equipment they need. They present all the intermediate stations until the Olympic competition. That's already embedded and it's not like in the past. Fortunately, we started early, and many of the things we do are being implemented globally."

Could it be that in the future we won't be able to hold Olympic games in the summer?

"This is an interesting and troubling issue. The entire world competition schedule revolves around holding the target competitions - the world championships, the Olympic Games and the continental championships - during the summer. For the outdoor sports this is a difficult problem. It is possible that major events scheduled to take place in the Northern Hemisphere will have to be moved to a more reasonable time. The World Athletics governing body has already announced that the World Athletics Championships will be held in the middle of September instead of August."

What about amateurs and non-competitive athletes? They also suffer from heat conditions that become extreme.

"The most important thing for every athlete is awareness, recognition of physiological and health competence and extremely careful risk management. The greatest danger lies in situations where untrained people decide they are capable of performing a physical challenge that is beyond their ability. All the more so during the transition period from winter to spring, then the body is not acclimatized at all. This is a real danger. It is important for those who train and are aware of their bodies to know how to choose comfortable training hours, wear appropriate clothing, protect themselves from radiation and observe a proper fluid balance and cool down the body during self-initiated breaks. Ego and ignorance are the greatest enemy, therefore it is important to manage the challenges of training and competition carefully and in consultation with experts."