magazine issue 12 2006 / Issue 1

Does Exercise Truly Make You Happy?

• written by Daniëlle van Versendaal
• edited by Hans IJzerman

Brain endorphins, or why mice keep running in their little wheel

What if the perceived causality between the healthy mind and body is erroneous? Suppose that, in general, happy people are just more fond of exercise, meaning that there is only a correlation? Or factors involved with exercising could operate independently and the effects of exercise are found in factors that accidentally come with exercise. More specifically, people suffering from depression could in fact benefit from exercise programs due to the fact that they engage in a social activity, exercising with other people and receiving attention in a constructive and positive way.

These critical views of this popular view that exercise would cause a more sane mind allows for a more comprehensive model of causality. Namely, physiological mechanisms and environmental factors could influence both exercise behaviour and effects on psychological wellbeing. There are many very interesting theories on physiological mechanisms of exercise could aid in the understanding of psychological well-being. One of those will be discussed here and is very interesting when seen in the context of psychological well-being.

Cordain Gotschall, Eaton, and Eaton (1998) hypothesized from an evolutionary perspective that human genotype responsible for physical activity is roughly the same as our ancestors that were hunter-gatherers. Our energy expenditure only accounts for 38% of our energy intake. It seems that current-day society demands less physical activity from us then the Paleolithic society 10.000 years ago. There are several studies that focus on activity requirements. From these it is concluded that people (and especially women) are exercising less when they get older. What could be the reason for this decline? Tergerson and King (2002) studied motivations and barriers that explain exercise and compared men and women. They found that men and women differ in their motivation; Women focus on their health, while men intend to gain strength.

A physiological mechanism that could account for both motivation to exercise and the positive effect on psychological well-being could be that of changes in brain endorphins (Dishman, 1997). More specifically, it is thought that beta-endorphin, a hormone released from the pituitary gland during vigorous exercise may be responsible (Goldfarb & Jamurtas, 1997). Exercise is healthy for us and is thus rewarded in our brains. Most organisms seem to be biologically driven to stay physically active. Caged rodents are often seen to run for several hours a day in their little wheel, although they certainly do not need to run a mile in order to obtain food or escape natural predators. The changes in the brain’s endorphins affects mood and can make exercise very addictive. One could probably even say that people engaged in professional sports probably are addicted for achievement!