Lose fat, forget fitness
2010-08-02 11:23
New York - If you're trying to bring your blood pressure to a healthy level, a US study suggests that how much you weigh is more important than how fit you are.
As expected, the study of about 35 000 people by the University of Texas Southwestern Medical Centre found overweight or obese people were more likely to have a high systolic blood pressure - the top number in a blood pressure reading.
But for those with a high body mass index (BMI) - a measure of weight versus height - how in shape they were only had a small impact on their blood pressure.
The researchers said these results suggest that people who are trying to decrease their risk for high blood pressure should focus on losing weight and increasing physical fitness should be a secondary goal.
"Obesity is such a strong predictor of blood pressure or hypertension risk that having a normal body weight is really what's going to drive your blood pressure" rather than your fitness level, said researcher Dr Susan Lakoski, a cardiologist.
Risk
At least in terms of lowering your risk for high blood pressure, she added: "It's not realistic to be fit and fat."
For the study, published in the American Heart Journal, Lakoski and her colleagues analysed data from about 35 000 patients, mostly white men, collected over the last 20 years at the Cooper Clinic in Dallas.
When patients came into the clinic, doctors measured their body composition, blood pressure, and fitness levels.
To determine how fit patients were, the doctors timed how long they could keep up a comfortable walking pace on a treadmill at varying inclines and speeds.
Using this data, the authors compared BMI, fitness levels, and systolic blood pressure of all patients to see if the three measurements were linked.
Among all participants, having a higher BMI was associated with having a higher systolic blood pressure, a correlation that has been found many times in the past.
But being fit had less of an effect on systolic blood pressure readings than BMI, and when the researchers looked at people of the same age and gender, fitness didn't seem to have any effect on blood pressure.
Negative effects
Only people of normal weight seemed to get much of a blood pressure benefit from having better fitness levels - possibly because fitness alone couldn't overcome the negative effects of being obese, Lakoski said.
But Lakoski said that for overall health and mortality risk, fitness is an important part of the picture.
"The ultimate thing we'd like to see is people obtain a lean body weight and start improving their fitness in the real world," she said.
One in three American adults has high blood pressure - above 140/90 - including more than half of those over 55. Having high blood pressure puts a person at greater risk for stroke, heart attack, and kidney disease.
The Centres for Disease Control and Prevention reports that high blood pressure will cost the US more than $75bn in 2010 from hospital stays and doctors' appointments, drugs, and lost time at work.