Bert Bakker is as fit as a fiddle. He was at the start of the Nijmegen Four Days Marches at 4:45 am on Wednesday morning and arrived at the finish at 11:10 am. Walked forty kilometers and no problems. Bakker, with a broad grin, is 75 years old.
He wears a white T-shirt that day and that is relevant because he is participating in a study by the department of integrative physiology at RadboudUMC. Fifty walkers will wear a white shirt for two days during the Four Days Marches this year and a black shirt for two days. At the end of the course – some walk thirty kilometers a day, others forty or fifty – medical students measure their temperature.
For example, research leader Maria Hopman, professor of physiology, can find out what keeps the walker cooler: white or black. “We tend to put on white when we fear heat. But we want to know if black also cools. Because, for example, beduins in the desert often wear dark clothes.” In any case, Bert Bakker liked it better in the white shirt than the day before in the black. “And yesterday it was a little less warm than today.”
The consequences of heat are very relevant to the Four Days Marches. The scientific research started in 2007 after the dramatic Four Days Marches a year earlier. Then it was so hot that two hikers died, some ended up in hospital and many became unwell.
To prevent that from ever happening again, a team was set up to meet each morning of the event and provide advice. The team includes a weatherman, an exercise physiologist (Hopman), a psychologist and the head of the medical service. Last year, the team advised not to run for one day, because it would be 38 degrees and the humidity would be high.
A wet towel on the neck
The team also often advises taking extra measures to limit risks: providing plenty of water along the route, sunscreen, a cap, a wet towel around the neck and sometimes starting an hour earlier than usual for the entire procession. For blisters, fainting participants and other suffering, Red Cross volunteers are along the route.
The team also does a lot of research into the runners’ health. Because the numbers of walkers are so large, 47,000 this year, that research into their physical condition before and after this enormous effort is possible and interesting every year. The elderly participate, diabetics, people with high blood pressure or cholesterol, with heart problems and even cancer. Everyone who wants to participate in the research responds to specific appeals in the newsletter for the Four Days Marches.
Over the course of fifteen years, Hopman and her colleagues have published at least fifty articles in scientific journals, based on research among the walkers of the Nijmegen Four Days Marches.
In 2018, for example, it turned out that you might as well walk far if you have muscle pain from medicines you take to lower your cholesterol.
In 2008 it turned out that one in five hikers drink too little on the way. “They are sometimes afraid that they will have to stop so often to urinate,” says Hopman. “But you have to drink a lot because you sweat a lot. Especially if you are overweight.” One fifth of the walkers therefore arrive at the finish with dehydration symptoms. Then they suffer from headaches and fainting.
Read also: In 2022, the Four Days Marches were shortened, but these walkers walked the Four Days Marches after all
Bert Bakker likes to buy drinks on the road now and then, he says. But not really in the hospitality industry. “Pepper expensive.” No, just give him the stands of associations along the road. Then a cup of tea or water only costs 1 euro.
Tonny Keizer from Doetinchem (61) is wearing a black shirt today. “It may be in my head, but I was much hotter than yesterday,” she says when she arrives at 11:45 am. She has her temperature taken and her blood drawn for the examination.
Little effort, she says afterwards, because she thinks the Four Days Marches are a wonderful social event. She walks alone, but never feels alone. “Everyone talks to you and helps each other.” She takes a week off from work. This year she is walking to raise money for a foundation that helps children who have had a traumatic experience at home. She drinks about 3.5 liters of water per walking day.
Heart and vascular disease
Another study that Hopman is also conducting this year is about heart damage. Five hundred random participants had their blood drawn on Sunday, in which the protein troponin is measured. After four days of walking (between 120 and 200 kilometres), the amount of troponin in the blood is measured.
“We also did that in 2009. We followed those people in the years that followed,” says Hopman. “Hikers who had the most troponin in their blood were later found to suffer from cardiovascular disease more often than hikers with little troponin.”
What good is knowing that? Hopman: “If you know that you are more susceptible to cardiovascular disease, you can do all kinds of things to improve your chances.” Exercise more, eat less, smoke less, and pay attention to blood pressure and cholesterol, for example.
A version of this article also appeared in the newspaper on July 20, 2023.