Pain & Physical Activity

Pain
Endorphins
Physical deconditioning
Physical reconditioning
Physical exercise and benefits for pain

Pain

Pain is a feeling that arises from injured or damaged body tissues. Special nerve endings convert the injury into pain sensations. These sensations are then transmitted up nerves along the spinal cord. From the spinal cord they are sent to various parts of the brain. Pain is a different feeling for each person, with perception of pain varying and affected by age, physical inactivity, existing medical conditions, and a whole range of other factors. Many people with long standing pain become inactive and don't do much exercise. Unfortunately, low activity levels lead to muscles becoming weak and wasting away, joint stiffness, weight gain and low mood. These factors can all contribute to worsening pain. There are many benefits of regular physical activity in reducing pain. Increased activity levels release endorphins (the body's own pain reducing substance).

Endorphins

Endorphins are a class of chemicals produced in the nervous system, which act to turn on the pain inhibitory system and help 'numb' pain. Endorphins act on receptor sites on special nerve cells located in the brain. These receptor sites function like a lock to which endorphins are the key. When lock and key are put together, the pain inhibitory system is turned on. Morphine, codeine and heroin have a similar structure to endorphins and can also act as keys and turn the lock.

Physical deconditioning

The human body is designed for movement and a lifestyle lacking exercise and physical activity has been linked to increased pain, illness and premature death.

Results of prolonged physical inactivity include:

Muscle wasting and weakness
Joint stiffening
Loss of calcium from the bone and increased brittleness of bones. These people are more likely to develop osteoporosis and possibly break bones.
Loss of red blood cells.
Decreased resistance to infection.
Increased body fat and development of obesity.

Physical reconditioning

To avoid or prevent deterioration of parts of our body and thus decrease pain, we need to develop a healthy exercise program. Physical exercise can help:

Improve muscle tone and strength
Increase joint flexibility.
Lower excessive body fat.
Increase our overall fitness levels.

Physical activity refers to all energy used up by movement. For example, everyday activities such as walking, riding the bike, and shopping, all help us use up energy. At least 30 minutes of moderate physical activity, like walking quickly, is enough to bring about many of these above effects. By increasing the level of activity, benefits will also increase. If someone has been sedentary for a while, they should start with less strenuous (straining) activities such as walking or swimming at a comfortable pace. Beginning at a slow pace will allow them to become physically fit without straining the body. Once their fitness levels have improved, they can gradually carry out more demanding activity.

For more information, see Preventing Cancer-physical exercise.

Physical exercise & benefits for pain

Regular physical activity provides many benefits in helping relieve pain:

In injured body tissue, appropriately planned exercise can promote healing.
Physical activity can prevent or stop further deterioration in many arthritic conditions.
Physical activity can help prevent the occurrence of painful injuries.
Physical activity promotes the development of endorphins, which are important in reducing pain (as discussed above).

Reference

Blair SN, Hardman A. Physical activity, health and well-being - an international scientific consensus conference. Res Q Exerc Sport 1995;66(4);v-viii. [Abstract]
Hanson RW. Physical Exercise [online]. 2003 [cited 22nd March 2006]. Available from: URL link
Health Benefits of Exercise [online]. 2005 [cited 22nd March 2006]. Available from: URL link
Hunter New England, NSW Health. Pain Matters - A Healthy Lifestyle [online]. 2005 [cited 22nd March 2006] Available from: URL link
Johnson LR. Essential Medical Physiology. USA: Lippincott-Raven Publishers; 1998. [Publisher]