Smokers lack motivation, are less physically active and are more likely to display symptoms of depression and anxiety, a new study indicates.

While smoking would be expected to affect fitness levels, this marks the first study to show that smokers are actually less active than non-smokers.

Scientists in Brazil asked 60 smokers and 50 non-smokers to wear pedometers for a minimum of 12 hours per day, over a six-day period.

The study found that during this time, smokers walked less than the non-smokers.

The scientists tested the smokers' capacity to take long breaths and found that their lung function was reduced. This affected their ability to exercise.

The smokers were also asked to report on their own health-related quality of life. The results showed that they were more likely than the non-smokers to report feeling tired, as well as symptoms of depression and anxiety.

They also lacked the motivation to change their behaviour.

"To our knowledge, this is the first study that has demonstrated a reduction in the objectively measured level of physical activity in daily life of adult smokers compared with non-smokers. Besides presenting poorer lung function, exercise capacity, quality of life and symptoms of anxiety and depression, smokers also walked less than non-smokers in daily life," the researchers concluded.

Details of these findings are published in the journal, Respirology.