Runners develop many wonderful habits, but knowing when to rest is not necessarily one of them. We love moving forward and many align our attitudes with Steve Prefontaine's "To give anything less than your best is to sacrifice the gift". Under such pressure we struggle to balance high mileage with life's other priorities. We sometimes ask too much of ourselves and then pay the price when a virus punches its way into a weakened body.
Moderate exercise is the healthy option. Training towards a 10K or half marathon has been associated with a much improved response to respiratory tract infections. Research has repeatedly concluded that regular, vigorous but not excessive, exercise reduces both the frequency and severity of respiratory tract infections.
As a runner you'll catch fewer colds, but what should you do when one of those wee viruses manages to sneak in and strike you down? Should you run? in a word, "No". Rest if you feel feverish, weak or achy. These symptoms are likely your body's inflammatory response to a virus that has spread beyond your throat and nose. Running will feel terrible, your performance will be reduced and if you train vigorously now you'll rapidly send viral replicants throughout every muscle, including your heart muscle. This is a really bad idea. However, if your symptoms are localised to your nose and throat you might just have a rhinovirus within mucous membranes and running would be OK. That said, personally I've grown to be cautious even with viruses that should stay out of the systemic blood stream. I guess I'm naturally cautious, but the caution is warranted because the damage caused to mucous membranes can blast a way through for secondary infections by viruses and bacteria with let's-take-over-the-whole-body agenda. Just as a scratch on your skin opens the door for opportunistic bugs so does the inflammation and disruption triggered by an initial respiratory tract-localised infection. Of course, if you've been eating well, sleeping soundly and running regularly your immune system is in perfect shape to zap the invaders before they've a chance to act. So the upshot is that as long as you feel well running is beneficial and should be continued. "Feel well" is the key part of that sentence. Pay attention to your body and what it is advising you.
Think about using your resting heart rate (HR) as an early warning sign of impending problems. Resting HR becomes elevated when your body is responding to infection, stress or other assaults. Daily monitoring of resting HR is probably the simplest, most useful and efficient means by which you can assess your body's readiness for, and response to, training. For these reasons the My Mojo Personal Log asks for your morning HR and charts it beside a timeline of your activities. If you're like my hubby, you'll enjoy the habit of daily measuring and recording; if you're like me, thrice-a-week will be perfectly fine and a valuable tool in tailoring my own training.
Here's hoping the bugs don't get you and if they do let them provide a good excuse to rest on the most wintry of days.