Teenagers who are prone to stress may have an increased risk of developing heart disease later in life even if they exercise regularly, a new study has found.

Previous research has suggested a link between stress and some health problems, including coronary heart disease, so Swedish researchers decided to look into this further.

They analysed data relating to almost 238,000 men born between 1952 and 1956, who were eligible for military conscription in their late teens.

The conscription examination included detailed medical and psychiatric assessments. The participants' subsequent risk of developing heart disease was then assessed between 1987 and 2010.

The study found that those who had low stress resilience in adolescence - in other words, a poorer ability to cope with stress - had an increased risk of developing heart disease.

This was the case even among those who were very physically fit, indicating that stress had a major role to play.

This means that even extremely fit teenagers may have an increased risk of developing heart disease later if they are unable to cope with stress.

"Low stress resilience in adolescence was associated with increased risk of coronary heart disease in middle age and may diminish the benefit of physical fitness.

"Our results further suggest that physical fitness varies by stress resilience level and that the protective effect of fitness in adolescence is reduced or eliminated in those with low-stress resilience. Effective coronary heart disease prevention might focus on promoting both physical fitness and tackling stress," the researchers from Örebro University said.

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

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