Exercise & Immunity

A recent article in the journal Brain, Behavior & Immunity published some interesting findings regarding exercise and immunity, especially with all the “flu” news going around today. There were three groups of mice which were given a devastating flu virus by injection. Incubation for this virus is 3 days, before onset of symptoms. The first group was given plenty of comfort and rest. The second group was exercised 20-30 minutes per day. The third group was exercised over 2 ½ hours per day. Most of the mice from all three groups started to show symptoms by the end of the third day. Over half of the mice in the first group died. Only 12 percent of the mice in the second group died. Over 70% of the mice in the third group died, and the ones that survived showed far worse symptoms than mice in either of the other two groups.

When compared to humans, we have similar findings, with less drastic results. Immunoglobulins have been sampled in athletes before and after prolonged strenuous physical activity, and there is a severe drop in count afterwards. With more detail, T¹ cells, which fight infection and cause inflammation, are more quickly replaced by T² cells, which cause an anti-inflamatory immune response. Without T² cells, T¹ cells would harm its own host. Exercise brings on T² cells at a faster rate, and heavy exercise suppresses T¹ cells, shutting down that first line of defense. Studies show that in both mice and men, moderate exercise brings about the most effective, healthy balance of T cells in fighting infection and virus.

These finding reinforce what physiologists termed several years back as the J shaped curve, in that moderate exercise does boost the immune system and stave off both the cold and flu. So many children get that moderate exercise all Summer long, and then go back to school with little or no exercise until the following Spring. Then we stay indoors all winter long with the excuse that it is too cold, wet or windy to play outdoors.   Is it no wonder that Fall and Winter are flu seasons?   If you want to stay healthy, get some moderate exercise!