Marathon Training May Actually Make You Ill

marathon training

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