Scientists have a good feeling about exercise

Physical activity is known to exert a powerful “feel-good” effect, brightening mood and enhancing mental health -- in fact, regular exercise may be as effective as medication for some people with depression.

A growing body of evidence supports this boost to psychological well-being, but the exact mechanisms are not completely understood.

“We know exercise makes people feel better, but we’re not exactly sure how,” says Patricia Dubbert, associate chief of mental health at the VA Medical Center in Jackson, Miss. Dubbert is one of a growing number of mental health professionals who are prescribing exercise as a way to relieve stress and lift spirits.

Existing theories fall into two categories, one focusing on the physiological changes prompted by movement and the other exploring the psychological benefits.

“On the physiological side, we know that exercise, especially aerobic exercise, can stimulate production of endorphins,” says Dr. Madhukar Trivedi, director of the depression and anxiety disorders program at the University of Texas Southwest Medical Center in Dallas.

Endorphins are morphine-like brain chemicals that can trigger feelings of euphoria and relaxation, and the endorphin-exercise connection is sometimes called “the runner’s high.”

“In a normal population, endorphins can lead to a transient mood-elevating effect,” Trivedi says. Patients with a depressive disorder, however, generally have an imbalance in certain brain chemicals including serotonin and norepinephrine.

“In these patients, the endorphin release from exercise may help modulate neurochemistry and restore balance,” says Trivedi, who is conducting research funded by the National Institutes of Mental Health that examines exercise as an adjunct therapy -- along with medication -- for patients with depression.

Some researchers speculate that repetitive, rhythmic physical activity -- such as swimming laps or running -- may exert a tranquilizing effect on the brain stem and nervous system in a manner similar to rocking a baby. Others note that exercise enhances sleep, allowing people to “recharge their batteries” more fully at night, resulting in more stable moods during the day.

Exercise in fresh air and sunlight also may have an antidepressive effect, especially during winter months for people prone to seasonal affective disorder.

“Exercise results in increased blood flow and oxygenation of tissues, which can have a beneficial effect on the entire central nervous system,” says exercise physiologist Tom Collingwood, president of Fitness Intervention Technologies in Richardson, Texas. “With more oxygen, everything from mental processes to physical functioning tends to work better.”

On the psychological side, one of the most frequently cited explanations for exercise’s mood-enhancing effect is the self-esteem boost that occurs when people exercise regularly.

“There are literally thousands of studies that show regular exercise increases self-confidence and self-efficacy,” says Collingwood. A variety of factors may contribute to this jump in self-esteem, including enhanced self-image from weight loss, improved appearance and better fitness to the satisfaction of mastering a new skill, improving physical functioning and accomplishing a goal.

In general, Collingwood says, “when people exercise regularly, they gain a feeling of control. Instead of being a victim of outside forces, they have found something positive they can do for themselves to take charge of their life. This boosts feelings of competence.”

Another psychological explanation centers on the social interaction involved in group exercise, says Toronto psychologist Kate F. Hays, who has written two guidebooks for using exercise as a therapeutic tool -- “Working It Out: Using Exercise in Psychotherapy” (American Psychological Assn., 1999), for mental health professionals, and “Move Your Body, Tone Your Mood,” (New Harbinger, 2001), for the general public.

“There’s a great deal of evidence that being socially connected is important to good mental health,” Hays says. “When you go for a walk with a friend or take an exercise class with a group of peers, it can help you stay connected with people and get the benefit of social support.”

Conversely, for some people, the chance to be alone can lift their spirits. “Some people enjoy taking time out of a busy day to exercise by themselves as a sort of moving meditation,” says Bonnie Berger, professor and director of the School of Human Movement, Sports and Leisure studies at Bowling Green State University. These exercise loners use their run or walk, she says, “as a welcome chance to have an intimate conversation with themselves.”

Because exercise appears to have a complex constellation of mind-body effects, the mechanisms by which physical activity exerts its feel-good effect “may differ among individuals and across different activities,” says Berger, who is working to clarify diverse characteristics of exercise that help facilitate the mood boost.

“The most important component is that it’s enjoyable,” she says. “Simply participating in any activity you enjoy will lift your mood.” Once people find a form of exercise they enjoy, it becomes a kind of active play, connecting them with the fundamental joy of being alive.

In addition, Berger says that exercise with an aerobic component (such as walking or running) and those that rely on regular deep breathing (such as yoga and weightlifting) also appear to enhance mood. “Regular abdominal breathing is a component of many stress-management techniques,” she says. “Any form of exercise that prompts enhanced, rhythmic breathing seems to boost mood.”

Some experts propose an anthropological theory to explain both the feel-good effect of exercise and the high incidence of depression (nearly one in 10 adults) in our sedentary society.

“Our bodies were created to move, and when we don’t move, we develop health problems,” says physiologist Collingwood. “We know inactivity is bad for the heart. Maybe it’s bad for the mind and the soul too.”