Physical activity, stress, and self-reported upper respiratory tract infection

Abstract

Purpose: Upper respiratory tract infection (URTI) is the most common reason for seeking primary care in many countries. Still, little is known about potential strategies to reduce susceptibility. We investigated the relationships between physical activity level, perceived stress and incidence of self-reported URTI.<br><br>Methods: We conducted a population-based prospective cohort study of 1,509 Swedish men and women aged 20-60 with a follow-up period of four months. We used a web-based questionnaire to assess disease status and lifestyle factors at the start of the study. We assessed physical activity and inactivity as total MET-hours (metabolic equivalent task) per day and perceived stress by the 14-item Perceived Stress Scale. Participants were contacted every three weeks via e-mail to assess incidence of URTI. They reported a total of 1,181 occurrences of URTI. We used poisson regression models to control for age, sex, and other potential confounding factors.<br><br>Results: We found that high levels of physical activity (>=55 MET-hours/day) were associated with an 18% reduced risk (IRR 0.82, 95% CI: 0.69-0.98) of self-reporting URTI compared with low levels of physical activity (<45 MET-hours/day). This association was stronger among those reporting high levels of stress (IRR 0.58, 95% CI: 0.43-0.78), especially among men (IRR 0.37, 95% CI: 0.24-0.59), but absent in the group with low levels of stress.<br><br>Conclusion: We found that high physical activity was associated with a lower risk of contracting URTI for both men and women. In addition, we found that highly stressed people, particularly men, appear to benefit more from physical activity than those with lower stress levels.<br><br>(C)2010The American College of Sports Medicine<br>