"If you are exercising and you are fit, your chances of developing hypertension are much less than someone else who has the same characteristics but is not fit," said Mouaz Al-Mallah, senior author of the study and a cardiologist at Henry Ford Heart and Vascular Institute in Detroit, Michigan.

One MET is the amount of energy expended at rest; anything above that represents a level of exertion. High-intensity workouts translate to more METs.

The researchers gathered data from more than 57,000 participants who were referred for a treadmill stress test between 1991-2009.

Those whose maximal exercise output was less than six METs had an over 70 percent chance of having high blood pressure at baseline compared to less than 50 percent for those with METs of greater than or equal to 12.

Those who reached 12 METs or more during the stress test had a 20 percent lower risk of developing hypertension compared to those reaching below six METs.

Of 8,053 new cases of hypertension diagnosed during the study, 49 percent were in the lower fitness (less than six METs) group and 21 percent were in the higher fitness group (more than 12 METs).

The study appeared in the Journal of the American Heart Association.

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