n, Medhaus, and Sandvik (1985) which took a group of forty-three clinically depressed men and women and first measured their mood by the Beck Depression Inventory (BDI). Next, these forty-three patients took part in a nine-week exercise program. Martinsen et al. were able to later conclude that from the decrease in the DBI depressive scores, exercise had improved the patient's moods. The general conclusion from this experiment and others is that exercise, to some degree, can decrease depression in those diagnosed as depressed.
             The current biological argument that supports the link between exercising and improved mood is convincing. Researchers are now studying the various ways the mind can alter people's moods, focusing their attention on the brain's neurotransmitters. The two most well known neurotransmitters are beta-endorphins and serotonin. Beta-endorphins are part of the mood regulating chemicals that reduces pain and can even induce euphoria. In fact, it is even now believed that the increase in beta-endorphins when exercising is the true cause of the euphoric state, "runner's high". (Artal).
             Also, serotonin is another chemical in the brain that has been successfully linked to mood (Lee). For instance, it is responsible for the availability of neurotransmitters at receptor sites. For the brain to maintain a stabilized
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