Ernesto Nakayasu, a biomedical scientist at the Pacific Northwest National Laboratory, says: "People who are highly physically fit may be more likely to develop viral respiratory infections immediately after vigorous exercise." Amid the expected physical changes that help our bodies maintain the increase in fluids, energy and oxygen required by exercise, there has been a decrease in molecules involved in respiratory inflammation, and this was accompanied by an increase in opiorphine, a peripheral vasodilator, according to a study published in the journal Science Alert.The team wrote in its paper: "Opurphine may increase blood flow to muscles during exercise regimen to improve oxygen and nutrient delivery."