The harder and more often you train, the bigger the strain on your immune system. A compromised immune system makes you more susceptible to common bugs being passed around.
Upper respiratory illness accounts for 35-65% non-injury-related presentation to a sports medicine clinic. In athletes, upper respiratory symptoms (URS) are most often related to common respiratory viruses, viral reactivation, allergic responses to aeroallergens and exercise-related trauma to the integrity of lung membranes.
Recurrent and/or persistent respiratory illness negatively impacts the health and performance of athletes and preliminary studies show a pro-inflammatory response and a dysregulated anti-inflammatory cytokine (chemical) response to intense exercise as a possible mechanism of respiratory inflammation.
Dietary supplementation with probiotics and selected antioxidants can reduce the incidence or severity of URS in some athletes.