The report by PhD graduate Dr Michelle Rogerson reveals the link between lack of exercise and higher levels of depression among people with coronary heart disease.
It showed that a self-devised 12-week exercise program, including a fortnightly check-up phone call, helped reduce depression levels.
"The less physically active people were, the more depressed they felt," Dr Rogerson said. "But by the end of the trial we found all of the depressed participants had increased their exercise levels and felt happier. It was a simple intervention but it had a major psychological effect.
"The regular call kept the need for exercise at the forefront of their minds rather than dropping off the radar, which can easily happen."
Dr Rogerson said she was surprised by the high levels of depression found among the participants in the study.
"It was quite worrying to find about 65 per cent of participants were at least mildly depressed following a heart event and that this rate dropped only to 50 per cent after a year. It's also likely that this figure is an underestimate because we assume people with very high levels of depression did not participate in our study.
"The danger is that if depression is not acknowledged and addressed the chances of it becoming chronic are much higher."
Dr Rogerson said heart attack victims often felt they had lost the ability and confidence to participate in exercise, which led to higher levels of depression. Participants in the study identified forced retirement, lack of motivation, fear of triggering an additional physical problem and lack of social support as other barriers to exercise.
"It's a major upheaval in their lives and people feel like they are older, less healthy and unable to be as active. It is important to be able to break this negative cycle with exercise regimes that they can design for themselves and maintain, like walking around the block or carrying an extra bucket of water out to the garden."
Dr Rogerson's thesis also found that people who believed they were more active, whether this was in fact the case or not, felt less depressed.
"Even the perception that a person felt active was enough to make them feel better about themselves."
