Last week we published a piece called, “Will Exercise Combat the Common Cold?”
http://hollywoodhealthletter.com/2013/04/23/will-exercise-combat-the-common-cold/#.UYSe4Pq3OL8.
This time around, we offer a different perspective.
Most Americans suffer from one to six colds per year, and are able to fight them off whether they exercise or not. Exercise and physical activity enthusiasts and athletes often wonder whether working out has any effect on the severity or duration of cold symptoms.
Research published by the American College of Sports Medicine (ACSM) indicates that moderate exercise during a rhinovirus-caused cold does not appear to affect symptom severity or duration. Although it is known that moderate exercise may decrease the risk of acquiring an upper-respiratory infection (URI), nothing had previously been documented to demonstrate whether exercise training while suffering from a cold would reduce or intensify the symptoms. Researchers decided to construct a study that might contribute to the body of information many athletes and exercise enthusiasts base their decisions on about how much to train during a cold.
Lead investigator Thomas G. Weidner, Ph.D., Ball State University in Muncie, Indiana, said “We know that colds kept some of the 1992 Winter Olympics athletes from competing at their best. We assumed that exercise could further compromise the immune system during an illness. So we hypothesized that even moderate exercise could prolong the severity and duration of a cold.”
Fifty moderately fit student volunteers (i.e., having a maximal oxygen uptake in the 40th percentile for age and gender) were recruited for the study. They were divided randomly between two groups: exercising and non-exercising. The exercising group worked out at specified times and under supervision, while the non-exercising group was instructed to be sedentary with the exception of walking to class or working at their part-time jobs. Each study participant was inoculated with a predetermined number of infectious particles of a rhinovirus and then all exercisers and non-exercisers were followed for a ten-day period. All participants were asked to refrain from self-treating their colds.
Prior to being infected, all subjects were asked to complete a
13-symptom checklist. Besides reporting regularly on their symptoms after the inoculation, study subjects kept a daily log of their physical activity. The exercise group trained at 70 percent of their measured heart rate reserve for 40 minutes at the same time every day, either running, stair climbing or bicycling.
At the conclusion of the study, analysis of exercise training data, physical activity profiles, symptom severity scores and actual mucous weight measurement showed no statistically significant difference between the exercising and non-exercising groups. Duration of symptoms (from peak infection to the end of the study) was lower by 44 percent in the non-exercising group compared with a 27 percent decrease in the exercising group, although these differences were not statistically meaningful. From these data, the authors conclude that exercise at this level apparently does not intensify cold symptoms by further compromising immune function. A possible reason for this is that the prescribed intensity of exercise was not enough to alter immune responses. High intensity exercise, as pointed out above, has been shown to have a negative effect on immune function during a URI.
The authors reiterated a useful model for exercising during a cold. If symptoms such as a runny nose, sneezing or a scratchy throat exist (so-called “above-the-neck” symptoms), it is probably safe for an individual to exercise at a lower intensity. If these symptoms recede in the first few minutes of exercise, intensity may be increased accordingly. Exercise is not, however, recommended for individuals experiencing “below-the-neck” symptoms of a cold, such as fever, sore muscles or joints, vomiting or diarrhea, or a productive cough. Persons with such symptoms are urged to allow the illness to run its course and resume physical activity when the cold is gone. The results of this study allow us to conclude that “above-the neck” symptom sufferers will not experience prolongation or exacerbation of their illness if they do moderate-intensity exercise.
This was the first study that specifically examined the influence of exercise training on a rhinovirus-caused URI. Rhinoviruses are thought to be responsible for only 40 percent of annual colds, however, so other types of virus cause the majority of these illnesses. It remains to be seen whether similar results can be observed for colds induced by those other types, or whether the colds they produce respond differently to exercise. Other forms and intensities of exercise, other populations, and other fitness levels must also be considered in future studies.
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