This paper reflects the research and thoughts of a student at the time the paper was written for a course at Bryn Mawr College. Like other materials on Serendip, it is not intended to be "authoritative" but rather to help others further develop their own explorations. Web links were active as of the time the paper was posted but are not updated.
2002 First Paper
The commonly referred to "Runner's High" is a euphoric, calm and clear state reportedly reached after a long period of aerobic exercise. There is no concise single definition for the phenomenon because it is immeasurable. The concept is soley based on reports of personal experiences. Also, exercise is said to have the effects of a general boost in mood and happiness. This theory is the basis for numerous depression treatment programs that incorporate exercise. Many believe this mood change is a result of both mental and physical factors. Psychologically, exercise causes a boost in self esteem, an improved self-image, confidence and feelings of accomplishment as well as a break from the other aspects of life (2). While these reasons to be happier during or after exercise are well accepted, the chemical processes behind the immediate "runner's high" and a lasting general mood change during and after exercise is greatly debated.
The first theory about the chemical cause of the "Runner's high" was put forth in the 1970's. Jogging was popularized around the same time a new type of brain chemicals was discovered . These chemicals, now called endorphins, were found to be very similar to morphine in chemical structure and pain killing abilities (7). In fact, morphine attaches to the same receptors in the brain as endorphins. The scientists found the similarities so striking that they actually named the chemicals 'endorphins', meaning "morphine" and "made by the body" (1). These endorphins became the popular answer to anything that gave pleasure (they are also commonly associated with orgasms). The theory that endorphins caused the high during exercise was supported when early research found that there were heightened levels of endorphins present in the blood stream during and after exercise (1).
Scientists found it hard to investigate the exact relationship between these new chemicals and the euphoric effects of exercising because of the variability involved in the qualitative nature of exercise difficulty and the intricacy of evaluating whether the endorphins were, not only present, but also responsible for the high. To this end, Virginia Grant, a psychologist, did experiments with rats comparing the behavior of rats addicted to morphine and rats that exercised. The experiment allowed rats to eat for one hour a day. Some rats were left in an empty cage the remaining 23 hours, while others were left in cages with wheels. Those left in the empty cages were able to eat enough in the eating hour to stay healthy, while those with the running wheels showed an inverse relationship between eating and running and eventually ran so much they died of starvation (1). It was concluded that exercise stimulated the same portion of the brain as addictive drugs. Any addictive drug causes a surge of dapamine in the brain, resulting in the building of the small proteins enkaphilin, dynorphin and substance P (1). Further, Rats who were in cage with a running wheel would run until these three chemicals were present in the brain. While research is still being conducted on the subject, this phenomenon with rats could help to explain the addiction to exercise sometimes seen in people with eating disorders. The dangerous combination of over exercising and anorexia is strikingly similar to the lowering of caloric intake of the rats the further they ran.
The experimentation with rats built a strong case that exercise is addictive; however, it failed to address the specific nature of endorphins in the process. The fact that endorphins are present during exercise is not surprising. Endorphins act as a pain reducer and are released when the body is in stress. The mere presence of the chemical does not prove that it is the main factor in causing the elation. Further, some scientist point out that the endorphins don't leave the bloodstream and therefore do not stimulate the receptors in the brain (1). Also, there are other chemicals within the brain capable of causing good feelings in a way comparable to those during and after exercise. Serotonin is one such chemical. Similar to endorphins, serotonin is released into a portion of the brain where it activates receptors causing heightened emotions and senses. Also, the chemical often times causes a suppression of appetite. However, there has not been much research done on the role of serotonin in the exercise process (3).
The most recent findings in the search has lead scientists to focus on a chemical called phenylethylamine, also found in chocolate (6). Phenylethylamine (PEA) had previously been found to relieve depression in two thirds of depression cases. There are theories that relate a low level of phenylethylamine with the presence of depression making it a natural candidate for possible chemicals surrounding the anti-depressant effects of exercise. Also, the chemical has been found to cause heightened activity and attention in animals (5). It is also notable that phenylethylamine has been able to boost moods as quickly as amphetamines, but without side effects or creating a tolerance to the chemical (5).
Ellen Billet of Nottingham Trent University studied the levels of phenylethylamine in 20 young men before and after exercising on a treadmill at 70 percent maximum heart-rate capacity. The men were asked to rate the level of exercise level they felt, and then were tested for phenylethylamine. Rise in the level of the chemical was around 77 percent with huge variances in levels between individuals (7).
It has become accepted in the scientific community that there is some sort of "runner's high" or general mood elation associated with exercised on a physical level. The research to find the processes behind this phenomenon have all shown the immediate chemical levels of people after exercise. However, the lasting ability of these effects are largely important to depression treatment and an overall healthy happy lifestyle. Donna Kritz-Silverstein from UCSD, found that exercise must be done on a regular basis to maintain the positive effects. She found that those who exercised had a lower Beck Deppression Inventory (BDI) meaning they were generally in a better mood. Ten years later, those who had stopped exercising had BDIs similar to those who had never exercised, while those who continued to exercise were able to maintain a low BDI (4).
The reaserch on the chemical processes behind, and on the lasting effects of exercise concerning its effects on mood is very new and still being done. There are incredible implications for the treatment of depression and the general ability of people to maintain happy life styles through exercise. Also, the study of these anti- depressant chemicals help to show the chemical properties of depression and mood. Further, the drug- like qualities of exercise allows an avenue for investigation of exercise addiction and the eating disorders with which it is often associated.
1)JS Online, a collection of articles by different people
2)International Association of Mind Body Professionals , a collection of articles about the mind and body and the interactions between the two
3)About.com Page, Informational page about psychology with new discoveries, articles and general information
4)UniSci Home Page, science page with articles on various numerous topics
5)Chocolate Information Page, a site which includes information about drugs, chocolate, and the chemicals behind these substances
6)BBC News Page, a page with the news in the UK
7)Cosmiverse Home Page, a page with science news and articles
8)Advanced Chemistry Developement Home Page, a site with the latest on chemistry
| Biology 103 | Course Forum Area | Biology | Serendip Home |