We know there are all kinds of wonderful outcomes that benefit the human body when we exercise. One great effect that seems to be under reported is the boost that our immune systems get from moderate physical activity. Although the mechanism through which this occurs is not quite understood, there is definitely a relationship, as well as a correlation between too much exercise and lowered immunity (which also results from high-intensity activity).
Noted Exercise Physiologist, Dr. David C. Nieman, fellow of the American College of Sports Medicine, has done extensive research on the topic at the Human Performance Lab at Appalachian University, North Carolina. He compiled the results in a report published in November 2010 that included data from his studies on exercise and immunity, as well as nutrition.
According to Dr. Nieman, at the time of publication, all adults suffer 2-4 colds per year and children 6-10. Now, a lot of this can be attributed to poor hygiene habits (i.e.. not covering sneezes and coughs, failing to wash hands thoroughly, etc.). There are risk factors too, including, but not limited to:
You see where this is going. It’s that last one on the list that we are concerned with here. What if by becoming more physically active, the frequency of getting sick and/or duration could be mitigated? Through various means of data-gathering, including studies with mice, surveys of runners vs. sedentary people, and well-designed studies on human exercise subjects, Dr. Nieman and colleagues came up with some interesting outcomes. The surveys yielded the fact that the exercisers reported 60-90% fewer incidence of becoming ill than their sedentary counterparts, such as a survey in which 81% of 226 runners had fewer colds. Other surveys revealed that those who considered themselves fit (a questionnaire was provided to help them determine this) spent about one-half the time when they did become ill before they were fully recovered and reported less severity of symptoms.
Physiologically, higher levels of immune-cell activity was noted in women who enjoyed a high level of fitness, including T-cells. The elderly were shown to improve antibody activity in response to influenza immunization after training for 10 months at a moderate activity intensity. It has been noted that movement throughout the body may help the circulation of antibodies and thus render them more effective in fighting viruses.
All of the great immune system-building effects gained from exercise were noted in subjects performing moderate activity and for a prolonged period of time. A cumulative effect takes place the longer the time period during which activity is performed (over several weeks or months), as well as the frequency per week (at least five days) and duration (30-45 minutes). Moderate-intensity exercise is defined by the American College of Sports Medicine as, using walking as an example, maintaining a brisk pace of 3 to 4.5 mph on a level surface inside or outside, such as:
At this pace you would be breathing harder, but not out of breath. It would be hard to talk without taking breaths in between words.
So if a moderate exercise is good, more of it, and more intense exercise must be better to help us stay well. Well, not really, according to research on athletes who performed activities such as marathons, triathlons, and other long-duration, high- intensity activities or who engaged in prolonged training without adequate rest and recovery. These subjects displayed increased levels of stress hormones, which increase risk for getting ill and negatively impacts immunity. Not that high-intensity exercise is bad when one is prepared for it (with a base level of conditioning to begin with), but it must be tempered with plenty of rest, good nutrition, and if one is already feeling ill, replaced with moderate exercise until recovery is apparent. Which brings the question many exercisers ask: "Should I exercise when I have a cold?"
The answer depends on factors such as severity of symptoms and how much energy the sufferer has to exercise vs. sparing it to fight a cold. In general, light to moderate exercise can help fight a cold and help lessen the duration, but be careful around others. For instance, if you are in a gym environment, cover your sneeze or cough with a tissue (and dispose of it properly) or practice the "elbow" sneeze rather than doing it in your hand and then touching things. Wipe down the equipment you are using with anti-bacterial wipes or spray cleaners that are usually available for these purposes, avoid touching your eyes or nose and wash your hands often. Finally, stay home and rest if you are running a fever or have muscle aches and chills. When in doubt, it will NOT hurt you or set you back in your fitness regimen if you take a day or two off. Just make a plan to get back to it (let someone else know so they can check on you to make sure you do so in case you are afraid of "falling off").
More research is being done to define how exercise can not only help protect our bodies from common colds, but also from cancers, inflammatory diseases such as arthritis and more. For now, consider exercise another tool in your "preventative medicine cabinet" of healthy habits to enable you to stay well and prosper.