Doing yoga, talking on the phone, swimming freestyle and painting the ceiling increase the risk of stroke, neurologists said yesterday.
These everyday activities could overstretch or compress blood vessels in the neck, blocking blood flow to the brain and inducing ischaemic strokes, Chinese University neurologist Yannie Soo Oi-yan said.
Other dangerous activities include sleeping in one sideways position over many months, driving too fast, boxing and archery.
'Strokes related to excessive neck extension or rotation during sports and work are not rare,' Dr Soo said.
There are two kinds of stroke: ischaemic, when the brain receives too little blood due to a blood clot; and haemorrhagic, when there is bleeding. In ischaemic strokes, the neck bends at an acute or awkward angle, compressing or overstretching and tearing the arteries, leading to clots.
Smoking, which hardens blood vessels, and high blood pressure increase the risk of ischaemic stroke. While ischaemic strokes account for less than 5 per cent of all strokes in people older than 50, world figures show they make up 5 to 10 per cent in under-50s.
Lawrence Wong Ka-sing, head of the division of neurology at Chinese University's faculty of medicine, said Hong Kong had 150 to 300 cases a year in patients under 50, about 10 per cent of the new cases of all strokes for that age group.
'But these are only the cases we know about,' Professor Wong said. 'We think there could be many more.'
Dr Soo said she had seen two cases of ischaemic strokes this year, both men in their 50s. One became partially paralysed while playing badminton and the other became nauseous and weak in his right limbs while rotating his neck at his desk.
People in their 40s and 50s are at highest risk - more than older people, who do less strenuous exercise. This goes against the common assumption that strokes only occur in the elderly. 'We have seen that strokes are occurring more in younger people,' Dr Soo said, noting people in this age group tend to smoke and might have hypertension.
Many more men than women have ischaemic strokes. 'Perhaps men smoke, drive and do these kinds of sports more,' Dr Soo said.
Renovation workers represent the profession at greatest risk because they often crane their necks to paint ceilings and to turn screws, she said.
The Occupational Safety and Health Council advises renovation workers to find a natural position when working in hard-to-reach places and using paint rollers with long handles or spray painting.
Most patients fully recover and such strokes are almost never fatal. 'It doesn't mean you have to just sit at home and do nothing. Just don't do anything excessively,' Dr Soo said.
Doing head rotations slowly and carefully, driving safely, and using hands-free headsets instead of cradling the phone between the ear and shoulder can reduce the risk of ischaemic strokes, said Ellen Ip, a physiotherapist at the Prince of Wales Hospital.
By the throat
Some little-known causes of carotid dissection, which leads to strokes
Holding phone between ear and shoulder
Sleeping on side
Tips to avoid damage:
Move head slowly when doing rotation excercises
Place documents on both sides of computer when working
Use hands-free headset
Turn head with torso when driving
Sleep flat on back
Avoid aggressive sports such as rugby
SOURCE: CHINESE UNIVERSITY