Researchers from the University of Wisconsin-Madison randomly assigned 154 people, aged 50 and older, to one of three groups: a mindfulness meditation group, an exercise group, or a wait-list control group. Participants in the meditation group received training in mindfulness-based stress reduction (a type of meditation based on the idea that an increased awareness of physical, emotional, and cognitive manifestations of stress may lead to a healthier mind-body response to stress). Participants in the exercise group received instruction and practiced moderately intensive exercise (using stationary bicycles, treadmills, and other equipment) during group sessions, and walked briskly or jogged for home exercise. Both interventions lasted 8 weeks, consisting of 2.5-hour group sessions each week and 45 minutes of daily at-home practice.

The researchers observed substantial reductions in acute respiratory illness among those in the exercise group, and even greater benefits among those in the meditation group. While not all of the observed benefits were statistically significant, the researchers noted that the magnitude of the observed reductions in illness was clinically significant. They also found that compared to the control group, there were 48 percent fewer days of work missed due to acute respiratory infections in the exercise group, and 76 percent fewer in the meditation group. Researchers stated that these findings are especially noteworthy because apart from hand-washing, no acute respiratory infection prevention strategies have previously been proven. The researchers concluded that future studies are needed to confirm these findings.