May 19 (HealthDay News) -- Getting in shape really does help you live longer, new research says.

People with high levels of physical fitness, called cardiorespiratory fitness, have a lower risk of dying from all causes of death, including coronary heart disease and cardiovascular disease, than people with low levels of cardiorespiratory fitness.

Researchers analyzed data from 33 previous studies that included 102,980 participants and 6,910 deaths from a variety of causes and 84,323 people with coronary heart disease or cardiovascular disease and 4,485 deaths caused by those conditions.

Cardiorespiratory fitness (CRF) was estimated as maximal aerobic capacity (MAC) expressed in metabolic equivalent (MET) units.

Participants were categorized as having low CRF (less than 7.9 METs), intermediate CRF (7.9-10.8 METs), or high CRF (10.9 METs or greater).

Participants with low CRF had a 70 percent higher risk for all-cause death and a 56 percent higher risk for coronary heart disease and cardiovascular disease events than those with high CRF, according to the study, published in the May 20 issue of the Journal of the American Medical Association.

Those with low CRF had a 40 percent higher risk for all-cause death and a 47 percent increased risk for cardiovascular disease than those with intermediate CRF.

The analysis suggest that a minimal CRF of 7.9 METs may be important to prevent mortality from all causes, including coronary heart disease and cardiovascular disease, the researchers wrote.

To have adequate CRF, men around 50 years of age must be capable of continuous walking at a speed of 4 m.p.h. and women at 3 m.p.h.

CRF can be assessed by exercise tolerance testing, researchers said. Still, it's rare for clinicians to consider CRF when evaluating future risk of coronary heart disease.

"It is possible that consideration of low CRF as a major coronary risk factor could be put into practical use in the clinical setting through identification of low exercise tolerance by exercise stress testing or in daily life by the speed at which a person can walk before experiencing exhaustion," the researchers wrote.

The analysis also found that a 1-MET higher level of MAC, which corresponds to 0.6 mile/hour higher running/jogging speed, was associated with a decrease of 13 percent in risk of all-cause mortality and a 15 percent decrease in risk of coronary heart disease and cardiovascular disease.

SOURCE: Journal of the American Medical Association, news release, May 19, 2009