Watching action movies could be dangerous for people with heart conditions, according to new research.
A study from University College London and Guy's and St Thomas' Hospital suggests those with weakened hearts could be negatively affected by watching a stressful film.
Researchers found blood pressure increased, the pace of breathing became faster and the heart's natural rhythm began to shift during a viewing of a clip from 2000 action thriller Vertical Limit depicting a shocking rock climbing accident.
The small study saw 19 people monitored via electrodes detecting activity in the ventricles of the heart. It is believed to be the first recorded instance of biological effects of mental and emotional stress on healthy conscious patients.
Researchers believe the changes in heart pattern are linked to the autonomic nervous system, which operates below the level of consciousness.
"This is the first time that the effects have been directly measured and although the results varied from person to person we consistently saw changes in the cardiac muscle," said study author Dr Ben Hanson, from the department of mechanical engineering at University College London.
"If someone already has a weakened heart, or if they experience a much more extreme stress, the effect could be much more destabilising and dangerous."
The film clip was chosen because it offered powerful stimuli related to its "dynamic nature, sustained effect and the combination of visual and auditory inputs", said joint study author Professor Peter Taggart, of the neurocardiology unit at University College London Hospitals.
Despite the findings, death by cinema remains relatively rare, though not unheard of.
In 2010, a 42-year-old Taiwanese man with a history of high blood pressure died of a stroke that his doctor claimed was likely triggered by "overexcitement" from watching James Cameron's Avatar in 3D.
That same year, an Indian student died after reportedly watching four horror films back to back at a hostel near the city of Visakhapatnam, in Andhra Pradesh, on the country's south-east coast.