Extra exercise may help depressed smokers kick the habit faster, according to a recent study.

Quitting cigarettes is a more complicated struggle when mental health is a factor. Researchers from An international team of researchers found that people diagnosed with depression smoke twice as often as smokers who are not dealing with the mood disorder.

While nearly one in five North American adults are regular smokers, a figure that continues to steadily decline, about 40 percent of depressed people are in need of a regular drag. The statistic motivated the researchers to investigate what was behind that higher percentage.

"The review should be seen as a call to arms," Grégory Moullec, co-author of the study and a postdoctoral researcher affiliated with Concordia's Department of Exercise Science, said in a statement.

After an 18-month study, researchers found that those who struggle with mental illness simply have a tougher time quitting, no matter how much they want to. The anxiety, cravings or lack of sleep that accompany typical attempts to quit cold turkey will have them scrambling for the smokes they might have sworn off earlier that evening. A person without clinical depression is better equipped to ride things out.

However, they found that a bit more exercise has been shown to reduce the compulsion to reach for a cigarette -- even if it is not enough to alleviate the symptoms of the depression itself. Quitting was found to be easier in the midst of even the most basic workouts, since withdrawal symptoms were reduced in the aftermath of regular walks.

"Our hope is that this study will continue to sensitize researchers and clinicians on the promising role of exercise in the treatment of both depression and smoking cessation," Paquito Bernard, first author of the study, said in a statement.

Researchers also suggest that those who have the hardest time shaking off the habit may have more mental health issues than they are actually aware of, shedding light on how the struggle to give up cigarettes can reveal depression that has not been adequately diagnosed.

Researchers said more research is needed to examine how exercise can play a role in helping to quit smoking.

"We still need stronger evidence to convince policymakers," Moullec said. "Unfortunately there is still skepticism about exercise compared to pharmacological strategies. But if we continue to conduct ambitious trials, using high-standard methodology, we will get to know which interventions are the most effective of all."

The findings were recently published in the journal Nicotine & Tobacco Research.