Can Too Many Miles Make You Sick?

Understanding How Stress Affects Your Immune System

Norm Klein was worried—worried about the health of some of the athletes he and his wife Helen had come to know as friends and fellow competitors during Norm’s 14-year tenure as race director of the Western States 100. "It was after I was no longer race director, in 2000, that I started observing what I believed was a cancer trend in runners who had competed over the years in the event," Klein says. The 20 athletes he refers to are or were all residents of northern or central California and northern Nevada; 15 men and five women, two of whom are now deceased.

Klein, a former surgeon, explains that it "seemed unusual that people in such excellent physical condition would be developing cancer." The majority of the cancers in the male runners were cancer of the prostate, while the women developed various unusual and rare forms of the disease. "The man who died was our best friend; he died 16 months after his prostate cancer diagnosis. The woman, who was in her mid-40s, died of a particularly vicious cancer that produced tumors and lesions throughout and all over her body. She was dead within a few months after winning the women’s division of the Rio Del Lago 100."

Was it possible that there was a connection between the high mileage these runners had maintained over the years and their developing serious, even terminal illnesses? Klein wanted to find out, so he called on Dr. Robert Lind, at that time the medical advisor to the Western States 100, for help. Upon hearing of Klein’s observations Lind was quickly caught up in the medical mystery and became equally determined to understand what was happening within the runners’ bodies.

The Complex Immune System

"Even though what Norm was telling me was anecdotal, I knew that something had to be going on. Since I was the medical advisor to the race I was familiar myself with many of the athletes’ health concerns. It seemed that there might be a connection between immune system dysfunction and the stresses runners endure when training for and competing in ultradistance events. But we had no proof," says Lind. "So I started searching for people who might be interested in pursuing a possible connection."

In 2001 Lind came upon an article written by Dr. David Nieman, Professor of Health and Exercise Science at Appalachian State University in Boone, North Carolina.

Nieman, a veteran of over 50 marathons and ultra events, had done extensive research on the pre- and post-race health histories of participants at the City of Los Angeles Marathon. What he learned, and had written about in the article, was that runners who trained more than 60 miles per week doubled their chances of getting sick in the days and weeks following the race. "This was exciting because it seemed to indicate that there was a real connection between strenuous training and illness. I contacted Dr. Nieman late that year about what we had observed in runners at Western States. As a result, through funding generated by the event participants, Gatorade and the Department of Defense, Nieman has been studying the effects of immune system response to stress caused by training for and competing in the Western States 100 ever since."

Lind explains that it’s because the immune system is so complex that few studies had been done prior to Nieman’s research. "Immune dysfunction is caused by five triggers: stress, infections, toxins, deficiencies and trauma. We’re only just beginning to learn how each of these triggers can affect the immune system, and in athletes we’re trying to understand what makes some of them more prone to illness than others. It’s like a superimposed type of stress that causes more problems for some runners."

In fact Norm Klein suggests that perhaps the demographic make-up of the Western States 100 participants and other 100-mile trail and mountain races may be a factor in compounding the stress the athletes experience physically. "These people are highly motivated and educated; the majority of them have five to six years of education past high school. The highest percentage are engineers, followed by attorneys, physicians, educators, dentists and CEOs. For some of them running got them out of bad circumstances in their lives — they smoked, or were alcoholics or took recreational drugs. Now that they’ve gotten older and slower they need a new challenge, so ultra runs are the next step forward. They’re people who push themselves very hard to succeed."

So what’s happening in the bodies of these highly-trained, goal-oriented athletes that’s causing them to fall ill, despite their seemingly excellent physical condition? "It’s all at the cellular level," says Lind. "Changes in the DNA that occur due to any alterations in the billions of codes it receives are a precursor to diseases, including cancer. It’s just going to take some time to understand it all better. We’ve now learned, for instance, that aspirin can reduce the chances of developing colon cancer by as much as 40 percent. There is no silver bullet yet for preventing stress-induced diseases in endurance athletes, but it will happen."

A Lab in the Field

As with the runners he studied who ran in the LA Marathon, Nieman conducts extensive examinations of blood and muscle tissue gathered from Western States 100 participants. His research shows that immune dysfunction often begins within hours after a runner has finished his or her event. Think back to the last time you trained for and ran a marathon. Did you develop a cold during the last several weeks of training? Perhaps you even had a sore throat and itchy watery eyes, which you may have blamed on allergies. And what about a week or so after the race? Did you develop an upper respiratory infection? Maybe you had to take an additional week or two of recovery time because you were sick. If this is what happened to you, you’re not alone. Intense prolonged exercise does have an effect on immunity, and it begins at the cellular level.

So far Nieman has determined that there has been no research on probiotics (live bacteria found primarily in dairy products) that indicates that the microorganisms work to prevent or counteract cell damage. However, he is working on developing the perfect "cocktail", a mix of supplements in a sports drink that will prevent cellular damage by promoting the development of macrophages, white blood cells whose job is to essentially "eat up" pathogens that develop from infections, viruses or stress. "Research in the lab, animal data, suggests that advanced supplements might in fact reduce infection and boost the immune system," Nieman explains. "We’ve already established that drinking one-half a liter of a six to eight percent carbohydrate sports drink one-half hour before a competition or workout lasting more than 90 minutes, one-half to three-quarters of a liter after and one to two cups every half-hour while running reduces the chances of developing an illness. Research shows that eight out of ten runners training 30-40 miles per week who followed this regime said that they were getting sick less. "Eventually we’ll find the right mix of specific supplements to incorporate into the carbohydrate sports drink to further protect the immune system," he says. According to Nieman, those supplements may be Beta Glucan (cultured extract of Baker’s yeast cell wall) and Quercetin, which is a type of bioflavanoid, a family of plant-derived supplements that have been shown to have antioxidant properties. "We should know by Christmas of this year if these two supplements are the ones that will work best."

Reducing Your Risk of Developing an Illness (Even Cancer)

If research shows that intense and prolonged exercise can suppress the immune system, thereby causing minor illnesses like colds and upper respiratory infections, could the stress of participating in marathons and ultras also be causing cancer in some athletes? "For six years we’ve been measuring the immune response in the Western States 100 participants, and based on our observations of these, as well as hundreds of other ultramarathoners and marathon runners over the years, I wouldn’t be surprised if there’s a connection," Nieman says. "Unfortunately, at this time no one has a database that clearly shows that these athletes have more cancers than those who don’t participate in endurance events."

The classic signs of overtraining (that too frequently runners ignore or attribute to aging) are a clear indicator, according to Dr. Kalish, that the immune system is suppressed. "Even something that seems as innocuous as a simple cold is a sign that there’s a problem. Cortisol regulates the immune system in the mucous membranes; when the athlete starts experiencing frequent runny or stuffed noses, coughing and sore throats, the first line of defense has already been broken." Kalish believes that, as Norm Klein observed, type A personality runners, which many of us are, tend to "run as we live," and the day-to-day stress of work, family and social life and running becomes too much for our bodies to handle. "It’s important for runners to realize that they can’t ‘exercise their way out of how they feel,’ and adult runners must understand that it’s not normal to get more tired just because you’re older," Kalish says. He further explains that when elite athletes’ immune functions are restored to normal they always perform better, and that once a runner makes changes in his or her lifestyle, most can get back to normal good health and regular training within six to twelve months.