Are “marathon sniffles” a thing?

It has been long thought that strenuous exercise such as running a marathon can leave the body vulnerable to infectious diseases as a result of a temporary suppression of the immune system. This is the result of the release of the stress hormone cortisol, which when high enough, can impair the immune system, for days after a race. The same mechanism explains why we tend to get sick when we are stressed at work or when we are studying for an exam since to the body this all means one thing: activate fight-or-flight response.

The idea of marathon sniffles originated from studies published in the 1980s and 1990s, whereby runners reported symptoms of an upper respiratory tract infection (such as the common cold) in the days and weeks following a marathon. Other studies looked more closely at the immune cells and discovered that during the early stages of exercise, immune cells flood the bloodstream but then fall dramatically post-exercise, to levels far lower than normal. This gave rise to the notion of the “open window”, which according to researchers persists between 3 to 72 hours after a marathon, during which time the suppressed immunity allows opportunistic bacteria and viruses to cause an infection.  

However, current research contradicts everything we’ve known so far. First of all, previous studies relied solely on the athletes’ perspective on their symptomatology and illness without an actual laboratory diagnosis of infection to back up the information.

Recent studies carried out tests on the athletes’ saliva and determined that actually only about a third of those who reported illness were actually diseased. It was also discovered that the probability of an athlete getting sick after a race is the same as the average population within the same geographical area. It was also discovered that the decrease in immune cells in blood is a result of the migration of immune cells to more exposed areas of the body that are more likely to get infected such as the lungs since the fast and heavy breathing increases the risk of inhaling pathogens.

Although running a marathon per se will not increase the chance of getting an infection, other factors such as inappropriate diet, lack of sleep and stress, can all be correlated with infections. Also, marathons usually involve a gathering of a lot of people and so it is easy for disease to spread.

The following are some tips to help prevent infections before and during your next marathon:

• Maintain proper hygiene by washing your hands regularly and using a hand sanitizer
• Establish a proper sleeping schedule and avoid sleeping less than 7 hours per night 
• Make sure to include enough carbohydrates in your diet, as well as fruits and vegetables – there is no need for supplements and vitamin replacement unless they are deficient!
• Allow periods of rest in between your training 
• Relax! Less stress means fewer infections