Marathon season is here. Thousands of runners are hitting the pavement, preparing for the long 26.2 miles ahead of them. While it may seem that marathon training is a great way to get into shape, studies show that it can actually make you sick.
The downside to marathon training
On 1 March 1987, thousands of runners took to the streets of Los Angeles for the annual city marathon, unaware that many of them were about to provide crucial evidence for a study that would inspire three decades of research into the relationship between exercise and the immune system.
Monitoring the race closely was David Nieman, a scientist at Appalachian State University in North Carolina, and a keen marathon runner himself with a PB of 2:37. Nieman had become interested in the connection between intense exercise and our susceptibility to colds or viruses some years earlier after suffering a debilitating bout of flu while at the peak of his training for an upcoming race.
Intrigued as to whether there was a link, he got in touch with the organisers in Los Angeles, detailing his plans to set up a study monitoring the competitors and recording how many fell foul of infection both before and after the race, compared to non-runners in the same city at the same time.
Over 2,000 of the competitors that year took part in his study, and the results seemed to confirm Nieman’s suspicions: nearly 13% fell ill in the week following the race compared to just 2% of the normal population.
Nieman’s results paved the way for a theory called the “elite athlete paradox”. While exercise is good for physical and mental health, extremely intense exercise can actually lead to a suppression of the immune system for a couple of hours – an open window for infection.
When Nieman published his findings in 1990, the elite athlete paradox was a groundbreaking new idea, leading to a wealth of interest from human performance experts to immunologists who began researching the underlying molecular processes in more detail than ever before.
They found that exercise actually stimulates a powerful anti-inflammatory response, a key part of the body’s naturally built-in healing processes. While intense, long duration exercise sends this response into overdrive – thus temporarily compromising the body’s ability to defend itself – regular moderate-intensity exercise can combat the low-grade inflammation underpinning many chronic diseases ranging from diabetes and cardiovascular disease to dementia, various cancers and depression.
From an evolutionary perspective, it’s thought that this anti-inflammatory reaction occurs because our bodies have evolved with movement. Regular bursts of moderate-to-high intensity exercise have formed part of our daily lives for most of the past 200,000 years, acting as a natural cleansing mechanism from any lingering inflammation.
Full Story: The elite athlete paradox: how running a marathon can make you ill
thumbnail courtesy of theguardian.com