Med Tent: Can Training and Racing Make Me Susceptible to Illness?

As a triathlon coach who is also a physician, one of the most common questions I get asked is whether or not training can predispose an athlete to become sick. This question has taken on particular significance in 2020, with the novel coronavirus COVID-19 responsible for sickening 32 million people at the time of this writing and for the deaths of 1 million of them—200,000 of whom were Americans. 

The relationship between exercise and illness is often misunderstood and, in the context of COVID, it really needs to be understood in order for athletes to make good decisions for themselves and for their families. With smaller race events beginning to take place and larger ones happening abroad and on the horizon domestically, athletes may be tempted to try and salvage what might otherwise be a lost season and participate in a race.

So what then is the answer about how exercise affects the immune system? This question can best be answered in the context of a pandemic by breaking it in to three different questions and answering them individually: 1) Can training/racing make me sick? 2) Am I more likely to get COVID participating in a triathlon? 3) If I have had COVID, is it safe to return to train/race?

Can training or racing make me sick?

It has long been recognized that elite athletes have a propensity for developing respiratory illnesses after intense competitions. For some time, the reason for this was not clearly understood, but eventually researchers recognized that this had something to do with a decrease in levels of a non-specific immunoglobulin being secreted. 

Immunoglobulin A, or IgA, is commonly found in the respiratory and gastrointestinal tracts where it binds non-specifically to invading viruses and other infectious organisms. IgA provides only a relatively modest first line of defense, but when levels of this immunoglobulin fall, the result can be susceptibility to infection. 

Other markers of immune function have also been seen to fall immediately after intense efforts and, in each case, recovery to normal levels takes about 24-48 hours. This period of one to two days during which immune function is depressed has come to be referred to as the ‘open window’ to infection.

Now it is important to note a few important caveats to these findings: First is that moderate, regular exercise has been definitively proven to improve immune function and decrease susceptibility to infection. So while a particularly prolonged and intense day of training may weaken immune function, normal day-to-day training actually strengthens it. 

The second thing to take in to consideration is the fact that decreased immune function is only one element in becoming infected. An athlete still must be exposed to an infectious agent while in this state to become ill. During this time of social distancing and mask wearing, it is actually much less likely than usual that this will happen!

Am I more likely to contract COVID participating in a triathlon?

This is a difficult question to answer as much will depend on the levels of infection in the locale where the event is held, the adherence to guidelines to mitigate disease transmission by race organizers and athletes, and the circumstances related to travel and lodging unique to each individual athlete. 

While the actual act of swimming, biking, and running is likely a low-risk endeavor, it is certainly not no-risk. And the times before and after the race will pose the most risk and uncertainty. It’s not biking, inherently, that’s problematic; it’s biking next to and hanging out with hundreds of other athletes who have also traveled from different regions, each interacted with dozens of other people, and may not be paying attention to minimizing virus spread in the midst of or after a hard effort. The choice to participate in an event should not be taken lightly as contracting COVID can have serious consequences not just for the athlete but for their loved ones and their community.

Still, the simple act of racing in a triathlon is unlikely to increase the risk of contracting COVID by an individual during that specific period any more than participating in any other outdoor event.

If I have had COVID, is it safe to return to train and race?

COVID-19 has proven to be a wily and dangerous foe. Aside from its high infectivity and mortality rate, in many cases even after patients have recovered, symptoms can persist for many months.

One of the potentially lethal consequences of COVID is the development of myocarditis, or inflammation of the heart. This has been reported as a rare complication in young, healthy athletes who are otherwise asymptomatic, but the actual number of people who develop this remains a mystery.

Around the world, cardiologists have struggled to develop guidelines to help athletes and coaches understand when and how to return to training after COVID infection. In the absence of hard evidence, most of this is expert opinion and thus far errs on the side of caution, with very conservative protocols designed to cast a broad net in an effort to catch the likely very small numbers who may be affected. Still, when you consider that non-COVID myocarditis is estimated to account for 8% of sudden cardiac death in otherwise healthy young adults during exercise, this level of prudence seems warranted.

Although guidelines are somewhat different, most share many of the same elements in their recommendations for return to exercise after COVID-19 infection:

• For COVID asymptomatic patients:
  • No exercise for 14 days after diagnosis confirmed
  • May consider cardiology screening but not required
• For COVID symptomatic patients:
  • No exercise at all while symptomatic and a minimum of 10 days of convalescence once symptoms resolve
  • If not hospitalized during illness, screening by cardiologist recommended prior to return to exercise with additional testing as warranted
  • If hospitalized during illness, comprehensive cardiology evaluation mandated prior to return to exercise

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In summary, triathlon training makes your immune system stronger, though intense efforts for prolonged periods of time can lead to an ‘open window’ for infection. You aren’t likely to contract COVID while doing a triathlon, but everything before and after the race are definitely associated with a higher risk. The magnitude of that risk will depend on many different things. Finally, for those who have had COVID, serious consideration needs to be given to getting screened for the potentially serious cardiac effects of the infection prior to returning to training.

Train hard, train healthy.

The MedTent will answer your science and medical triathlon-related questions. It’s written by Jeff Sankoff, an ER physician, triathlete, and coach who runs TriDoc coaching and hosts the TriDoc podcast.