How to alter your marathon training or triathlon training when battling illness

When you are experiencing symptoms of a cold or the flu, should you continue your marathon training or triathlon training as normal, do you need to cut back, or must you stop entirely? It all depends on the type and severity of your symptoms:

Conquering a Cold

Most experts agree that it is okay to continue exercising as normal when you have a mild or moderate head cold with symptoms such as sinus pressure, runny nose, cough and sore throat. But a cold that has moved into your chest, with symptoms such as chest congestion and tightness, is more likely to negatively affect your training—and if a cold negatively affects your training, then your training may negatively affect your cold! So in such cases, listen to your body and use common sense. If you are reasonably comfortable when you train despite your symptoms, and if training does not worsen your symptoms, go for it. Otherwise let discretion be the better part of valor and take a day off.

Fighting the Flu

Until recently there was virtually unanimous agreement in the medical community that one should not exercise while battling flu symptoms such as nausea, vomiting, fever, diarrhea, and body aches. Newer research, however, has called that dictum into question. For example, a 2009 study by researchers at the University of Iowa found that moderate daily exercise improved flu symptoms in mice infected with a flu virus. The key word here is “moderate.” Attempt only short, low-intensity workouts when you are experiencing flu symptoms, stop exercising immediately if you feel horrible while working out at a low intensity, and simply avoid exercise completely if you feel miserable even thinking about working out. So, as with colds, listen to your body and use common sense in deciding whether to train with the flu.

Protecting Your Immune System

While exercise generally strengthens the immune system, strenuous individual workouts such as long marathon training runs or lengthy speed sessions temporarily suppress immune function. Therefore you should also consider your training workload when trying to decide how to respond to symptoms of illness. If you’re feeling under the weather yet you’re training moderately, it is unlikely that you’re suppressing your immune system and making it harder to beat the virus. But if you’re in very heavy training, it might be best to cut back your workouts to give your immune system a quick boost so it can beat the virus instead of letting it linger and possibly affect your training for many weeks.

This recommendation receives support from the results of a 2002 study by Ola Ronsen of the Norwegian Olympic Training Center. Ronsen measured various markers of immune system activity in endurance athletes after completing a pair of workouts on a single day on two different occasions. On one occasion they rested for three hours between workouts and on the second occasion they rested for six hours. And guess what? There was a significantly greater increase in stress hormones that compromise immune function in the short-rest trial than in the longer-rest trial.

These findings suggest that an endurance athlete who’s already sick will probably get well quicker if he or she takes measures to train in a more rested state, either by reducing the frequency of workouts or by making them less challenging. In this regard then, colds and flus should be dealt with much like those aches and pains that indicate incipient injuries. In other words, responding to impending illness or injury by “aggressively taking it easy” may prevent a much greater setback from developing.