What chemistry teaches us about walkers
The Four Days Marches in Nijmegen, the annual walking event that attracts tens of thousands of participants from the Netherlands and abroad, has a unique relationship with chemistry. Walking, enjoying and suffering together gives a chemistry that bonds, something which every participant recognises. There is, however, an even more direct relationship between walking and medical applied chemistry. That has been the case since the 2006 edition of the event, which was cancelled after the first day following the deaths of two people caused by the considerable walking effort required during extremely high temperatures.
Since then, the Four Days Marches board has been advised about the weather conditions and the fitness of the participants. The advice is provided by a meteorologist, a psychologist and a physiologist. Furthermore, since 2006, the event has had a chemistry field lab, which has expanded into an annual testing ground for large-scale research into the effects of long walks on the human body.
Three months before the start of the event, 120 walkers are selected and tested for a wide range of blood values as well as their general health. They report to the field lab before the walk on the first day for a baseline measurement. On each of the walking days, students and PhDs from Radboud university medical center measure the walkers before and after the walk. The information gathered includes medicine use, condition of the heart and blood vessels, heart rate, biomarkers in the blood and even inhaled substances in the lungs. These measurements must provide answers to questions such as, which substances increase or decrease due to walking, and what happens to the blood pressure, heart rhythm and fluid level? Which parts of the route were experienced as particularly tough? How does the body respond during successive days of exertion?
Maria Hopman, Professor of Integrative Physiology at Radboud university medical center and an adviser to the Four Days Marches board, praises the innovative level of the equipment and the use of chemistry. ‘Of course, all of this could be done in a hospital, but it’s great that this now takes place in a field laboratory located in a school sports hall behind the finishing line.’
The research results are made available months later once the data have been processed and analysed, says Thijs Eijsvogels, senior researcher at Radboud university medical center. According to him, the studies over the years have shown that the body adjusts to the high requirements imposed on it during the Four Days Marches. ‘That is striking’, according to Eijsvogels, ‘as one would expect that walking during the four days would be experienced as increasingly tougher. Instead, the reserves increase because the body quickly adapts through factors like an increased plasma volume.’
One example of the influence of the measurements is how these have led to the route on the first walking day of the Four Days Marches being reversed. It transpired that the last part of the route on that day was too tough, and that the effort required could better be made at the start of the day.
Eijsvogels states that the fluid balance forms a real risk. On the first day of the Four Days Marches, one in five participants was found to be dehydrated, that means about 11,000 people. Dehydration increases the risk of fainting due to low blood pressure. Significantly more men than women suffer from dehydration. Eijsvogels: ‘This is because men sweat more and drink less, possibly to look tough.’
Eijsvogels concludes that over the years, the measurements have clearly shown that participating in the Four Days Marches results in fewer disruptions of the heart rhythm and a lower heart rate. According to him, this underlines the fact that regular exercise, such as long walks, add an average of three to six years to a person’s life.
Photos: Radboud UMC