Since the launch of the 4Days Marches research program, we have learned a great deal about the effects of walking on the human body. This year, the 4Days Marches researchers will present the most important scientific findings from the past twenty years and open their doors to all participants. From body temperature and muscle strength to hydration and blood pressure, walkers will have the opportunity to undergo a range of tests and gain valuable insights into their own health.
Are you dehydrated after a day of walking? How much does your body temperature rise? And what effect do all those kilometers have on your muscles? During the 2026 4Days Marches research program, participants will get answers to these and many other questions.
Central to this year's activities is the impact that twenty years of research during the 4Days Marches has had on walkers, science and event organization. Visitors can take part in tests measuring body composition, muscle strength, blood pressure, vascular health, fluid balance, balance and body temperature. It is a unique opportunity to experience first-hand what two decades of research have taught us.
Professor Maria Hopman, lead investigator and Professor of Physiology, says: ‘After twenty years of 4Days Marches research, we have gained an increasingly detailed understanding of what happens in the bodies of walkers, from rising body temperatures to changes in the heart and muscles. This year, we are opening our doors to everyone. Walkers will have the opportunity not only to complete their kilometers, but also to learn more about their own health. Everyone is welcome.’
Visit us: All walkers are welcome!
There is plenty to discover. Researchers and staff members will explain the major findings from the 4Days Marches research program. Visitors can also visit a dedicated information desk to ask questions about exercise, walking and the human body.
In addition, participants are warmly invited to submit their own research ideas and questions in our suggestion box. Perhaps your idea will help shape future research.
Opening hours:
- Sunday 19 and Monday 20 July: 11:00 a.m. – 5:00 p.m.
- Tuesday 21, Wednesday 22 and Thursday 23 July: 1:00 p.m. – 5:00 p.m.
Location: Research Center, Waldeck Pyrmontsingel 75, Nijmegen, next to the Wedren event grounds.
Twenty years of 4Days Marches research: key findings
The 4Days Marches research program was established following the 2006 edition of the event, which was halted after a single day due to an extreme heatwave. In response, Professor Maria Hopman of Radboud university medical center initiated a research program to study the effects of prolonged walking and physical exertion.
Over the years, research has focused on topics such as cardiovascular health, fluid balance and body temperature regulation. Key findings include:
- The first walking day places the greatest physical demands on participants.
- During a walking day, body temperature rises by an average of one degree Celsius.
- One in five walkers does not drink enough during a walking day.
- Signs of cardiac injury can occur after a walking day; these markers may be predictive of future cardiovascular disease.
- People with type 2 diabetes require less medication as they increase their training for the 4Days Marches.
- Walkers around the age of 80 have a biological age that is estimated to be, on average, 8.2 years younger than their chronological age.
- Walking for 30 to 40 minutes per day reduces the risk of cardiovascular disease.
- Walkers who use statins do not experience more muscle complaints or muscle damage after a walking day than other participants.
- The ability to regulate body temperature decreases with age.
- Increased vegetable consumption lowers blood pressure in walkers with elevated blood pressure.
White or black clothing? Cap or no cap?
If temperatures rise significantly during the 2026 event, Hopman hopes to revisit a question that has intrigued both researchers and walkers: which clothing color is better during exercise: white or black? A study conducted in 2023 at temperatures around 25°C found no significant difference between the two. ‘We want to know whether the results are different at higher temperatures’, says Hopman.
Participants in this study will alternate between wearing white and black clothing during different walking days. In addition, another group of walkers will walk one day with a cap and another day without one, allowing researchers to investigate any cooling effects of headwear.
In both studies, researchers will measure the effects on the body, including skin temperature and core body temperature. Since body temperature typically rises by approximately one degree Celsius during a walking day, the studies aim to determine what role clothing color and wearing a cap may play in managing heat stress.
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Pauline Dekhuijzen
wetenschaps- en persvoorlichter
