Many of us have been suffering colds and flus this winter. I thought I had been lucky and healthy enough to ward off illness, but having house mates and office mates with colds, flus, and pneumonia I have succumbed to the dark side. With a long race looming next weekend I am torn with the decision to train or rest, many of us I'm sure have wrestled with this decision as well.
Well I did a quick Google search and here are some results:
If you think that you have a simple cold without systemic symptoms, exercise at a low heart rate and easy level of perceived exertion (long-slow-distance pace or easier) for a short period of time. If you are any sicker than stuffy-nose-sick, you should skip the run altogether. ~ Scare Tactics to Prevent You From Exercising While Sick.
From the same article:
Nutrients are mobilized (e.g., amino acids, the building blocks of protein), which the sick person uses to make infection-fighting substances.
During an infection, the body becomes catabolic (the opposite of anabolic) and breaks down muscle protein. The degree of muscle catabolism and protein loss is related to the height and duration of the fever caused by the infection.
The amino acids that are liberated from muscle are scavenged by the liver and used as an emergency energy source (glucose production via gluconeogenesis) and as the building blocks for acute phase proteins, which the body employs to fight infection.
David Nieman, Ph.D., who heads the Human Performance Laboratory at Appalachian State University, and has run 58 marathons and ultras, uses the "neck rule." Symptoms below the neck (chest cold, bronchial infection, body ache) require time off, while symptoms above the neck (runny nose, stuffiness, sneezing) don't pose a risk to runners continuing workouts.
In my case, my symptoms are sore throat and stuffed sinuses so my take is to continue with easier workouts and monitor how I feel. Read the articles and make your own assessment. The interesting element from the first article is the breakdown of muscle and importance of amino acids in the fight against infection.