A fascinating new study published in Cell*​ shows how exercise triggers a multitude of internal responses, among them being responses by the immune system. The paper is described by the New York Times as the “most comprehensive cataloging to date of the molecular changes that occur during and after exercise and underscores how consequential activity — and inactivity — may be for our bodies and health”​.

We’ve known for  years that exercise and immunity go hand-in-hand, and it’s not always beneficial. Moderate exercise promotes immune function, and individuals who exercise for one to two hours a day get 30-50% fewer infections than those who are very sedentary, according to Prof Mike Gleeson from Loughborough University in the UK.

Speaking to our European edition recently, Prof Gleeson explained: “This benefit is mostly thought to come from the increased 'immunosurveillance' effect. When you do exercise your heart rate increases and more blood is pumping through the body and this releases white blood cells that are the main part of the immune system and are normally stuck to the blood vessel walls.

"These white blood cells come into free flow and the white blood cell count increases by 10-100%. If you exercise for more than 40 to 60 minutes, this can cause an additional increase and this increased white blood cell count can last for several hours after the exercise.

“The cells in the blood present any foreign material they find in the blood as they get filtered through the lymph nodes. These lymph node cells are the cells that create an immune response to any infection trying to take hold in your body, so the greater that degree of blood flow the greater the degree of infection surveillance in your body.”