Have you ever gone for a run outside when it’s freezing out and come home only to have a crazy cough for the next day or so? We have too — so we did some research on winter exercise and how to stay healthy when working out in the cold.
Working Out and Your Immune System
Until recently, many scientists believed that exercise reduces the body’s ability to fight off infections. Past studies had found, for example, that after workouts, people had fewer infection-fighting white blood cells in their bloodstreams than before working out, suggesting that their immune system had been weakened.
A new review of studies about exercise and immunity indicates that the interactions between exercise and immunity are far more intricate than scientists once suspected. Encouragingly, it seems that a few simple precautions, including consuming carbohydrates during exhausting workouts, might help to keep our immune systems robust.
The New York Times sat down with a sports science lecturer to discuss carbohydrates and exercise. Below is a summary of the conversation! (for the full text click here http://nyti.ms/2xugatM)
Q. Why would exercise affect the immune system in the first place?
Dr. Peake: Exercise is a form of stress. The immune system responds to stress.
Q. What actually happens to the immune system during a workout?
Dr. Peake: White blood cell numbers typically increase in the blood during exercise, much as they would during an infection. Body temperature rises, and immune cells move from the lymph nodes, spleen, the walls of blood vessels, and the bone marrow into the bloodstream.
Q. And after exercise?
Dr. Peake: The number of white blood cells in the bloodstream, especially a type of cell that is particularly good at fighting infections known as natural killer cells, rapidly falls. People often have fewer natural killer cells in their blood after exercise than before they started. For many years, it was thought that exercise was destroying these cells and causing your immune system to be weakened.
Q. But it isn’t?
Dr. Peake: We believe that the cells are not destroyed. It’s more likely they move out of the bloodstream and to other regions of the body.
Q. Can this development leave us particularly vulnerable to infections after a stressful workout?
Dr. Peake: Yes.
Q. What if the exercise is relatively moderate, like a brisk walk or easy jog, instead of a more intense workout?
Dr. Peake: Evidence suggests regular moderate exercise protects against upper respiratory illnesses, whereas regular intense exercise increases the risk of upper respiratory illnesses.
Q. For people who train hard and would prefer not to repeatedly catch colds, is there any way to maintain a healthy immune response?
Dr. Neubauer: Eating carbohydrates during vigorous exercise may help, because carbohydrates maintain blood sugar levels. Having stable blood sugar levels reduces the body’s stress response, which in turn, moderates any undesirable movement of white blood cells.
Q. How much carbohydrate? And when?
Dr. Neubauer: Most people only need carbohydrates during high-intensity or prolonged exercise that lasts for 90 minutes or more. For them, between 30 and 60 grams — which is 1 or 2 ounces — of carbohydrates per hour during exercise could minimize immune disturbances related to exercise. Consuming carbohydrates in the first few hours immediately after strenuous exercise also helps to restore immune function.
Q. Any additional advice for those of us who work out and wish to stay well?
Dr. Peake: Washing your hands often and avoiding contact with sick people will also help.