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Weightlifting linked to risk of glaucoma

Now that the holiday feasting is over, many people step up their exercise regimes to get back in shape. But new research shows that you may want to take extra precautions before hitting the weight machines.

Weightlifting may increase pressure in eyes

Researchers in Brazil found that lifting heavy weights, especially while holding breath, is linked to an increase in intraocular pressure, or pressure inside the eye.

They warn that this can increase the risk of glaucoma, a disease in which unusually high pressure within the eyeball damages the optic nerve and can result in permanent vision loss.

The results of the Brazilian study appeared in the September 2006 issue of Archives of Ophthalmology, a publication of the Journal of the American Medical Association (JAMA).

Aerobics vs. weightlifting

Intraocular pressure is usually decreased after aerobic exercises such as running and biking. But weightlifting appears to have the opposite effect ? especially when combined with the Valsalva manoeuvre, a weightlifting technique that involves exhaling forcibly with the mouth and nose closed.

This phenomenon also occurs in individuals who play wind instruments, particularly the trumpet, or when a person coughs or vomits.

The study was led by Dr. Geraldo Magela Vieira, MD, of the Institute of Specialized Ophthalmology and UNIPLAC School of Medicine in Brasília, Brazil. Vieira and his team measured intraocular pressure during weightlifting in 30 males age 18 to 40 who all had normal eye pressure and did not have glaucoma.

The bench press test

Participants did two versions of a bench press exercise, each time lifting the weight four times.

For the first version, participants lifted the weight (first repetition) and pressure was measured in the right eye. Participants then lifted the weight three more times and during the last repetition, held their breath.

For the second version, pressure was measured in the left eye prior to beginning the exercise, and the participants lifted the weight four times, breathing normally throughout. Eye pressure was then measured during the last time (fourth repetition).

During the first round of exercise, intraocular pressure increased in 27 of the 30 participants, by an average of 4.3 millimetres of mercury. During the second round, pressure increased in just 18 of the men by an average of 2.2 millimetres of mercury.

Holding breath raises eye pressure

Vieira and his team speculated that the increased eye pressure could be due to the Valsalva manoeuvre and the "greater intrathoracic (chest) pressure caused by the air retained in the lungs when the subjects held their breath during intraocular pressure measurement."

The authors also note that a certain type of glaucoma (normal-tension glaucoma) is more common in individuals who are subjected to frequent changes in eye pressure.

Caution to glaucoma patients

"Prolonged weightlifting could be a potential risk factor for the development or progression of glaucoma,' they wrote. 'Intermittent intraocular pressure increases during weightlifting should be suspected in patients with normal-tension glaucoma who perform such exercises," they conclude.

As always, check with your doctor or eye-care professional before beginning any exercise regimen.

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