The Science of Exercise

Top line: Regular exercise is associated with improved mental well-being and a lower incidence of depression.

Have you ever noticed that you feel great after going for a run? Do you love working out or playing sports on a regular basis? It turns out that you are not alone, and that exercise may have a big effect on mood and mental well-being. While it might be no surprise that exercise can improve your mood, a good deal of scientific research has been conducted to discover the possible reasons for this.

Some researchers argue that exercise may act as a diversion from negative thoughts, and the mastery of a new skill may be important. There is evidence to indicate that social contact between people who are working out or involved in sports may be an important source of satisfaction as well. Still others think that physical activity causes the brain to release chemicals called endorphins that cause one to feel good after exercising. Most of the researchers looking at exercise and mood compared groups of people who were exercising to those who were not. They then looked to see if those who were exercising felt better in the short term. Some researchers compared exercising to treatments for depression such as antidepressant medications or cognitive-behavioral therapy. The vast majority of studies have shown that there is a significant association between exercise and improved well-being. It has proved more difficult, however, to show that exercise directly causes mental well-being; people who are happier, after all, may simply be more inclined to exercise.

The Cochrane Review (the most influential review of its kind in the world) has produced a landmark metaanalysis of studies on exercise and depression. They picked 23 rigorous studies out of a pool of more than one hundred. The conclusion was that exercise had a “large clinical impact” on depression.

Among the studies that support the theory that exercise directly causes improved mental well-being (as opposed to vice-versa) is one that looked at the effect of exercise on older adults with clinical depression (Blumenthal et al., 1999). The authors compared exercise to a commonly prescribed anti-depressant medication (Zoloft), and found that both were equally effective in reducing depressive symptoms. In contrast to these results, a group of researchers from the Netherlands found that exercise may not be nearly as important as genetics in determining one’s mental well-being (Stubbe et al., 2007). These researchers looked at pairs of identical twins in which one twin exercised significantly more than the other, and found that there was no significant difference in their levels of happiness.

Diet and nutrition can be beneficial to psychological well-being. A supporting study by Hakkarainen et al. in 2004 observed 29,133 older male smokers. Participants in the study recorded their meals, and the researchers examined those men who consumed more fatty acids from margarine and junk food. The researchers found that ingestion of those foods was associated with increased depression, anxiety, and insomnia. However, in contrast to these results, a group of researchers examined the improvements in well-being associated with exercise or micronutrient supplementation. After 17 weeks, the researchers followed up with study participants and found that neither supplementation nor exercise had a significant impact upon the well-being of the participants.

Sleep is very important to one’s well-being and quality of life. It is recommended that we get eight hours of sleep a night. A study done by Smaldone et al. from 2007 examined the effects of sleep and well-being. The study consisted of 68,418 children and adolescents, and the participants logged in journals and completed questionnaires. The researchers found that inadequate sleep was associated with family issues, school trouble, physical symptoms, and depressive symptoms.

In conclusion, there is a great deal of evidence that exercise, diet, and sleep are associated with improved mental-well being and a lesser incidence of depressive symptoms. Nevertheless, there is still controversy in the scientific community as to whether they cause improved mental well-being, or whether those with improved mental well-being have a predisposition for exercise and a balanced diet. The truth may lie somewhere in the middle.

To view the original article