Why am I fit but sick?

by Stephen Cheung

The cold facts on immunity

Your blood is the home to many immune agents. Among others, your white blood cells, lymphocytes and natural killer cells fight off foreign substances and germs. They all increase in concentration in your blood with a bit of exercise.

However, while a little bit of exercise and fitness is terrific for strengthening your immune system, either too little or too much both have the effect of weakening your immunity and increasing the risk of contracting minor infections, such as colds and the flu.

The average cyclist goes well beyond what scientists regard as moderate exercise and lands squarely in the danger zone of weakened immunity. This is true for acute bouts of heavy exercise, with numerous studies showing weakened immune systems and a greater incidence of upper respiratory tract infections or other illnesses in the week following ultra-endurance efforts.

It is also true for chronic training. It doesn’t help that many pro and amateur cyclists train so much with not enough recovery that they are chronically on the edge of overtraining. The harder you train, the more you have to take care to avoid getting sick.

Preventative medicine

Of course, a greater chance of catching a cold isn’t going to stop you or me from pursuing our passion for this sport. The main thing to do is to take as many preventative measures as possible to keep from getting sick. See ‘5 Top Tips for Staying Healthy.’

You’re still sick. Now what?

If you take all the preventative measures possible and still end up with an infection, do not take it lightly and start making plans to adjust your training for at least the week following. I would always err on the side of taking one to two days completely off once you start feeling sick.

Remember, your body is working hard to fight against the illness already, so let it do its job without having to deal with the additional stress of training. You’ll likely be back to full health faster than if your body is multi-tasking. Some TLC from your significant other for a day or two will help, too.

Once you get back on the bike, resist the temptation to hammer out hard intervals immediately to make up for “lost” time. Start with a couple days of easy riding. It can take your body as long as a week to recover fully from even a minor cold. Remember, it was the overexertion that helped to get you sick in the first place. It’s always better to be undertrained and healthy than trained but sick.