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Through scientific experimentation and observation, it is shown that exercise can reduce depression chemically, physically, and mentally. Today, almost everyone experiences stress, sleeping problems, low self esteem, depression, and muscle tension -- exercise can help with all these symptoms.

In a survey of 50 college students, I found that 100 percent suffer from stress, 70 percent have sleeping problems, over half of them suffer from low self esteem, almost half of them experience depression, and 85 percent experience muscle tension.

Just like most of these students surveyed, I have experienced all of these symptoms at some time or other. As a biology student I asked myself how I could reduce these symptoms, and I researched and read articles that explained how exercise accomplished this. I will cite a few experiments that I came across, explain some of the chemical and physical process that exercise induces, and go over possible doubts you may be having.

Let’s start by looking at a few of the many experiments that study the effects of exercise on depression and their outcomes.

• In 1999, the Duke University Medical Center studied the effectiveness of exercise versus antidepressants. (1) They studied 156 patients, males and females, who had Major Depression Disorder (MDD) for 16 weeks. One third was put on antidepressants, another third was put on a strict exercise schedule, and the rest of them were given a lower dose of antidepressants and a less strenuous exercise routine. They were all assessed for aerobic capacity, life satisfaction, self-esteem, and anxiety. Although initially antidepressants began to work faster, after 16 weeks they found that exercise and antidepressants were equally effective to reduce their depression.

• In 2000, the University of Jyvaskyla studied the direct effect of exercise on depression.(2) They interviewed 663 patients over an eight year span to check their exercise level along with their depression symptoms. They used a medical scale called Beck’s 13 item depression scale to evaluate the severity of depression among the patients. It was found that the patients that had not been exercising had a large increase in depression, but those that had maintained a constant exercise schedule were less clinically depressed.

So exactly how does exercise reduces depression? Exercise has a huge effect on on your muscles, joints, lungs, heart, and metabolism as well as the chemical balances in your brain and nervous system. According to an article in Health A to Z (3), exercise improves your health and attitude by sending oxygen to your brain, increasing your blood flow and heart rate, in turn releasing muscle tension. Exercise also increases the longevity of your life by reducing the risk of heart disease, diabetes, and colon cancer because it induces the removal of toxins and waste products. It also reduces bone loss because bones require weight bearing exercise during developement in order to be stronger later in life. Exercise also raises your self-esteem because it controls weight and builds and maintains strong and healthy bones, muscles, and joints, as well as improving the condition of your skin.

Looking from at the nervous system, several neurotransmitters are released, which transmit information within the brain and from the brain to all parts of the body. Serotonin is released, which is a neurotransmitter that is essential for learning, sleep, and mood control. Endorphins are our ‘pain regulators’ and natural opiates, connected to euphoric feelings, appetite regulation, and the release of sex hormones. Continuous exercise contributes to an increased production and release of endorphins, resulting in a sense of euphoria that is often called “runner's high.” Phenylethylamine is also released, which is a stimulant that gives you feelings of euphoria and happiness. This is also found in chocolate.

The release of phyenylethylamine was shown in an experiment that took place at Nottingham Trent University in 2001. (4) Students took urine samples from 20 men after they had not exercised for a whole day. The second day, they made all the males exercise for half an hour on a treadmill at a steady pace, and took another urine sample. When tested for the presence of phenylethylamine, the samples taken from after exercising had seventy seven percent more.
Norepinephrine, another neurotransmitter, is also released during exercise. Norepinephrine increases heart rate and blood pressure, speeds up our metabolism and cellular respiration, burns fats into fatty acids, and relaxes the bronchial muscles in our lungs to open up and relax our air passages.

Not only does exercise increase good neurotransmitters, it reduces the level of a hormone called cortisol, which is responsible for stress. So your body is more healthy, your brain is releasing positive endorphins and removing negative hormones, you sleep better, feel better, and live longer.

You may still be skeptical. What about people that are depressed despite a daily exercise routine? A presently known chemistry of depression is due to a low level of neurotransmitters throughout the body, or an imbalance of them. Therefore, exercising should increase the neurotransmitters and decrease the symptoms of depression. However, the causes of depression are not fully understood. We know this because antidepressants that raise or regulate different levels of neurotransmitters are only 60 to 70 percent affective according to Dr. Petros Markou. So, the other 30 to 40 percent of people affected by depression are depressed due to an unknown cause, which might not be affected by exercise.
So by experiments we know that exercise is an effective substitute for antidepressants, also we know that exercising improves your health, increases your life span, sends positive neurotransmitters throughout your nervous system, and gets rid of stress hormones. Therefore, exercise can help to reduce stress, sleeping problems, depression, low self-esteem, and muscle tension.


References
1. Blumenthal JA, Babyak MA, Moore KA, Craighead WE, Herman S, Khatri P, Waugh R, Napolitano MA, Forman LM, Appelbaum M, Doraiswamy PM, Krishnan KR. Effects of exercise training on older patients with major depression. 1999 Oct 25. Department of Psychiatry and Behavioral Sciences, Duke University Medical Center. 27 Nov. 2004 <http://www.biopsychiatry.com/exercise.htm>.

2. Lampinen P, Heikkinen RL, Ruoppila I . Changes in intensity of physical exercise as predictors of depressive symptoms among older adults: an eight-year follow-up . May, 2000. The Finnish Centre for Interdisciplinary Gerontology, and Department of Health Sciences, University of Jyvaskyla. 27 Nov. 2004 <http://www.biopsychiatry.com/exerdep.htm>.

3.Melissa Tennen. “Exercise Your Depression Away.” Health A to Z: Your Family Health Website. 2 Nov. 2004. Health A to Z. 28 Nov. 2004 <http://www.healthatoz.com/healthatoz/Atoz/dc/caz/ment/depr/alert11022004.jsp>.

4. Szabo A, Billett E, Turner J. Phenylethylamine, a possible link to the antidepressant effects of exercise?. Oct. 2001. Department of Life Sciences, Nottingham Trent University. 27 Nov. 2004 <http://www.biopsychiatry.com/peaexercise.htm>.