help people prone to anxiety become less likely to panic when
they experience those fight-or-flight sensations. After all, the
body produces many of the same physical reactions — heavy
perspiration, increased heart rate — in response to exercise.
They tested their theory among 60 volunteers with heightened
sensitivity to anxiety. Subjects who participated in a two-
week exercise program showed significant improvements in
anxiety sensitivity compared with a control group (Depression
and Anxiety, 2008). “Exercise in many ways is like exposure
treatment,” says Smits. “People learn to associate the symptoms
with safety instead of danger.”
In another study, Smits and his colleagues asked volunteers
with varying levels of anxiety sensitivity to undergo a
carbon-dioxide challenge test, in which they breathed CO2-
enriched air. The test often triggers the same symptoms one
might experience during a panic attack: increased heart and
respiratory rates, dry mouth and dizziness. Unsurprisingly,
people with high anxiety sensitivity were more likely to panic in
response to the test. But Smits discovered that people with high
anxiety sensitivity who also reported high activity levels were
less likely to panic than subjects who exercised infrequently
(Psychosomatic Medicine, 2011). The findings suggest that
physical exercise could help to ward off panic attacks. “Activity
may be especially important for people at risk of developing
anxiety disorder,” he says.
Smits is now investigating exercise for smoking cessation.
The work builds on previous research by Bess Marcus, PhD,
a psychology researcher now at the University of California
San Diego, who found that vigorous exercise helped women
quit smoking when it was combined with cognitive-behavioral therapy (Archives of Internal Medicine, 1999).
However, a more recent study by Marcus found that the
effect on smoking cessation was more limited when women
engaged in only moderate exercise (Nicotine & Tobacco
Therein lies the problem with prescribing exercise for
mental health. Researchers don’t yet have a handle on which
types of exercise are most effective, how much is necessary, or
even whether exercise works best in conjunction with other
“Mental health professionals might think exercise may be a
good complement [to other therapies], and that may be true,”
says Blumenthal. “But there’s very limited data that suggests
combining exercise with another treatment is better than the
treatment or the exercise alone.”
Researchers are starting to address this question, however.
Recently, Madhukar Trivedi, MD, a psychiatrist at the
University of Texas Southwestern Medical College, and
colleagues studied exercise as a secondary treatment for
patients with major depressive disorder who hadn’t achieved
remission through drugs alone. They evaluated two exercise
doses: One group of patients burned four kilocalories per
kilogram each week, while another burned 16 kilocalories per
kilogram weekly. They found both exercise protocols led to
significant improvements, though the higher-dose exercise
program was more effective for most patients (Journal of
Clinical Psychiatry, 2011).
The study also raised some intriguing questions, however.
In men and women without family history of mental illness,
as well as men with family history of mental illness, the
higher-dose exercise treatment proved more effective. But
among women with a family history of mental illness, the
lower exercise dose actually appeared more beneficial. Family
history and gender are moderating factors that need to be
further explored, the researchers concluded.
Questions also remain about which type of exercise is most
helpful. Most studies have focused on aerobic exercise, though
some research suggests weight training might also be effective,
Smits says. Then there’s the realm of mind-body exercises like
yoga, which have been practiced for centuries but have yet to be
thoroughly studied. “There’s potential there, but it’s too early to
get excited,” he says.
buffering the brain
It’s also unclear exactly how moving your muscles can have such
a significant effect on mental health. “Biochemically, there are
many things that can impact mood. There are so many good,
open questions about which mechanisms contribute the most
to changes in depression,” says de Groot.
Some researchers suspect exercise alleviates chronic
depression by increasing serotonin (the neurotransmitter
targeted by antidepressants) or brain-derived neurotrophic
factor (which supports the growth of neurons). Another theory
suggests exercise helps by normalizing sleep, which is known to
Video: Watch Temple University exercise
psychologist Michael Sachs, PhD, discuss
how to get reluctant exercisers off the couch.