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28.09.2009

Bulging biceps register too high blood pressure

If you've been going really hard at your weight training for a couple of years, your arms are probably so thick that doctors can no longer automatically measure your blood pressure correctly. Researchers at the Mexican Universidad de Guadalajara came to this conclusion after studying two hundred bodybuilders.

When doctors measure your blood pressure, they wrap a band – medics call it a cuff - around your arm and pump it up. For most people the medium size fits, but a large size is also available on the market.

Westerners' arms have grown in circumference in the last decades. This is mainly a result of the obesity epidemic, but in a miniscule number of cases this is due to the fact that a miniscule part of the western population enjoys weight training more than watching TV. The Mexicans were curious to know whether doctors were still able to take reliable blood pressure measurements for this group.

The researchers did an experiment with the contestants in the Mexican National Fitness and Bodybuilding Championship. They measured their blood pressure with the standard medium cuff and with a large cuff. There were actually four bodybuilders whose blood pressure could not be measured at all. Their arms were so thick that none of the cuffs were big enough.

The researchers discovered that for the subjects whose arm measurement was less than 33 cm there was little difference between the measurements taken with a medium or a large cuff. But when it came to bodybuilders with an arm measurement bigger than 33 cm things went wrong – especially with the systolic blood pressure measurement [this is the pressure when the heart contracts and pushes the blood through the arteries].

The measurement comes out higher [read: too high] if you measure the blood pressure of highly muscled arms with a too small cuff, the researchers conclude. The figure below shows the blood pressure measurements done on arms measuring more than 33 cm. You can read off the difference between measurements taken with the normal and with the large cuff.

In some bodybuilders a measurement taken using a normal-sized cuff results in a low value for the blood pressure, but in most cases the error is upwards. On average, a measurement taken with a too-small cuff results in the systolic blood pressure being overestimate by 8 mm Hg.

If a bodybuilder is unlucky this too high reading means the person will be told that his or her blood pressure has risen dangerously high. That's enough to get a person worried, as nobody likes to be told that they're suffering from a chronic disease that could shorten their life. And of course it's a real bummer if you're prescribed blood-pressure reducing medicines, which have all sorts of side-effects, when you don't even have high blood pressure.

Source:
Blood Press Monit. 2009 Aug;14(4):166-71.