Adults who considered themselves physically fit or who more likely engaged in regular aerobic exercise, had fewer and milder colds, according to a new study published in the British Journal of Sports Medicine.
Finding a cure for the common cold is unrealistic given that more than 200 different types of viruses cause Upper Respiratory Tract Infections (URTIs). But, reducing their incidence and severity could go a long way toward the more than 1 billion colds each year suffered by adults and children, not to mention the estimated $40 billion price tag.
The purpose of this study was to examine the relationship between both physical activity and physical fitness level with URTI during a 12-week period. Half of the subjects were studied Jan to April 2008 while the other half were studied August to Nov 2008.
A group of about 1,000 adults (60% female, 40% male) participated in the study. Forty percent of respondents were young adults, 40 percent were middle aged and 20 percent were over 60 years.
During the study period, participants assessed their URTI symptoms and monitored their severity. Based on their responses, a severity score (0= not sick to 7= severe) and symptom score (0= do not have symptoms to 7= severe) was recorded each day.
In addition to URTI scores, data was collected on diet, lifestyle and physical activity levels. Respondents were divided into three groups based on perceived fitness level: low, medium and high. They were also grouped by activity level per week (# times exercised): low (<1 time), medium (1-4 times) or high (>5 times).
Not surprisingly, the average number of day’s participants had a cold was higher in the winter than in the fall (13 vs. 8 days). But, the relationship between fitness level and the number and severity of URTIs experienced did not change as a result of season.
Increased physical fitness had a positive effect on the incidence and severity of URTIs. Participants in the high fitness level and high exercise frequency groups had 43-46 percent fewer days with an URTI; had 34-41 percent fewer symptoms and the severity of their symptoms were 32-41 percent lower when compared to their least physically fit and active counterparts.
Older age, high or medium fitness level, low or medium BMI, lower education, being married or male, eating 3 or more servings of fruit per day and lower stress levels were each associated with an average of 5 or fewer days with a cold.
Researchers theorize that regular moderate exercise stimulates a recirculation of cells from the innate immune system and decreases URTI risk. Stress hormones, which can suppress immunity, are not elevated during moderate exercise.
The authors said that although the immune system returns to pre-exercise levels within a few hours, each exercise session may improve immunosurveillance against pathogens that reduce overall URTI incidence and symptomatology.
The Bottom Line
While I have always believed firsthand that regular physical exercise lowers the chance of catching a cold, until now I never had scientific evidence. But, this new study is intriguing.
As the winter months near, it’s good to know that maintaining an exercise routine – even if it means you have to move it indoors – has an additional payoff like not having a head cold and not having to call in sick.