Boost Your Immune System and Improve Immunity With Exercise
Exercise and Immunity
Exercise is a great way to boost the activity of our immune system and reduce the risk of disease. The immune system is constantly protecting us from dangers, but it works better under some conditions than others. Its job is to attack and destroy cells, particles and molecules that can damage our body and make us ill.
The immune system protects us from threats that enter the body from the outside or are created within the body. We inhale potentially dangerous viruses, bacteria and fungal spores. We also eat them in our food. Our cells and molecules are damaged due to activity and chemical reactions within the body and due to the environmental toxins that we absorb.
Our immune system is always on duty to fight invaders and remove damaged cells and particles. Our lifestyle can help or hinder its action, however. Researchers have found that regular, moderate exercise improves the functioning of the immune system. Keeping the immune system healthy is important at any stage of life, but it's especially so in our later years when the immune system often needs some help and the risk of certain diseases increases.
The Immune System
The human immune system is an amazing and very complex network of cells, chemicals and processes. Discovering how the system works is an active area of scientific research, since it's so important in preserving our lives.
Researchers have discovered that exercise has significant effects on our immune systems. These effects are usually beneficial but are sometimes harmful. Moderate exercise performed regularly helps the immune system to function better while intense exercise seems to hinder its function.
Since scientific reports describe how exercise affects specific components of the immune system, it's helpful to know a little bit about some of these components. White blood cells are a major part of the immune system. Some are phagocytes. These engulf and destroy pathogens in a process called phagocytosis. (A pathogen is a microbe that causes disease.)
Phagocytes in Action
The Five Types of White Blood Cells (or Leukocytes)
Destroy microbes by phagocytosis (surrounding and engulfing the microbe)
Neutrophils are the most abundant white blood cell.
Have multiple functions, including killing parasites
Eosinophils become more abundant during allergic reactions.
Release histamine and heparin (an anticoagulant) to stimulate inflammation and blood flow in a damaged area
The increased blood flow during inflammation helps heal damage, but basophils may also be involved in allergies and asthma.
Attack invaders directly, help other cells attack or make antibodies, depending on the type
Three types of lymphoctes are B cells, T cells and Natural Killer (NK) Cells.
May become macrophages, which destroy bacteria and dead cells by phagocytosis, or dendritic cells, which help other components of the immune system do their job.
Monocytes are the largest white blood cell.
Natural Killer or NK Cells
Starting an Exercise Program
It's very important that a newcomer to exercise begins their fitness program with gentle sessions. The duration and intensity of the sessions should be increased gradually. Anyone who is very overweight or who has a serious health problem should seek their doctor's advice before starting an exercise program.
Moderate Versus Intense Exercise
Researchers are examining the effects of single exercise sessions on the immune system as well as the effects of regular exercise sessions. They are also taking into account whether the exercise sessions are moderate or intense.
A moderate exercise session is considered to be one that causes the participant to be mildly out of breath and to sweat lightly. An intense or vigorous exercise causes the participant to breathe hard and sweat heavily. In general, health agencies recommend that people get 150 minutes of moderate exercise each week.
Types of Exercise for Boosting Immunity
Someone trying to improve their fitness level may choose just one type of exercise or alternate between several types. Examples of good exercise choices include walking, running, cycling, swimming, dancing, inline skating, fitness classes and many types of sports. Some people might like to incorporate exercise into their daily life, such as by walking or cycling all or part of the way to work, school, stores and appointments.
Anyone starting a fitness program should check whether warm-up or cool-down exercises are required for their chosen exercise or exercises and whether stretching or strength training is advisable.
Health experts say that any form of exercise - even a slow walk - is better than none at all. For the best results with respect to health and immunity, however, the exercise should involve a moderate degree of effort. For example, a walker should walk briskly or uphill either continuously or in intervals to increase the intensity of their workout.
Benefits of Moderate Exercise for the Immune System
Although the relationship between immunity and moderate exercise isn't always clear and isn't completely understood, some interesting discoveries are being made.
- In mice and humans, regular, moderate exercise reduces the risk of colds and flu compared to the risk in sedentary mice or humans. Any cases of flu that do develop in the individuals that exercise are relatively mild.
- After a moderate exercise session the concentration of macrophages in the blood increases temporarily. A similar observation is made for the concentration of lymphocytes in the blood.
- During exercise there is an increased rate of blood flow in the body. The blood contains agents of the immune system.
- Regular, moderate exercise helps us to lose weight if we need to and helps us to maintain a weight that is healthy for our body. Being overweight hinders the immune system.
- Exercise also helps us to get a good night's sleep. Lack of sleep depresses the activity of the immune system.
- In addition, exercise reduces stress. Chronic stress has a negative effect on the immune system.
Detrimental Effects of Strenuous Exercise on Immunity
Strenuous exercise appears to be less beneficial for the immune system than moderate exercise. This is by no means clear, however.
- In mice, repeated periods of long and intense exercise lead to an increased rate of colds and flu compared to the risk in moderate exercisers and sedentary individuals. In addition, the infections are more severe in the mice that exercise strenuously.
- In humans, after a long and strenuous workout the activity of neutrophils, monocytes and lymphocytes is temporarily depressed and they behave less effectively. When a lymphocyte encounters an invader it normally multiplies rapidly, a process known as lymphocyte proliferation. This process is reduced after a prolonged exercise session, especially in one that lasts at least one and a half hours and is performed at moderate to high intensity.
- People who run in a marathon (which is just over twenty-six miles in length) have a depressed immune system for hours to days after the event. Observational studies suggest that the runners have an increased risk of getting sick during this time period. In addition to the immune system changes described above, researchers have noticed that the concentration of NK cells is decreased as well. There are also changes in the levels of immune system chemicals.
- It's been observed that some of the immune system changes noticed after heavy exercise are prevented if carbohydrate is ingested during the exercise.
Why Strenuous Exercise Might Not Be So Bad for Immunity
Although a long and intense exercise session seems to temporarily increase the risk of a person getting sick, the infections that develop tend to be upper respiratory tract infections and aren't serious. In addition, in some people exhibiting symptoms of a respiratory tract infection after strenuous exercise, no infectious agent has been found. It's been suggested that the "infections" in these people are actually caused by increased exposure to airborne allergens and irritants.
In most people, the benefits of become fitter, stronger and leaner from prolonged and strenuous exercise are considered to outweigh the disadvantage of a temporary susceptibility to a respiratory infection. The infections may be more bothersome for elite athletes who train rigorously for a long period of time. It's not a good idea for anyone to exercise to exhaustion, however.
Other Factors That Can Boost the Immune System
There are other things that we can do to help our immune system in addition to getting regular, moderate exercise. These including eating a healthy diet that is filled with beneficial nutrients and is low in sugar, salt and the less healthy fats, getting enough sleep, reducing stress, and avoiding smoking and excessive alcohol intake.
Helping our immune system stay in top condition is very important for preventing or weakening both minor and more serious illnesses. Boosting our immune system when necessary can improve both our health and our quality of life.
Moderate and Vigorous Exercise - Information from the National Health Service
Exercise and Immunity - Information from the National Library of Medicine
Sport, Exercise and the Immune System - A detailed look at the effect of exercise on the immune system
Marathon Training and Immunity - Immune system changes during marathon training
© 2012 Linda Crampton
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