Reported May 19, 2009
Being physically fit may help people to live longer, say
researchers who suggest exercise stress tests could be useful for doctors in
predicting heart disease risk.
People with high levels of cardiorespiratory fitness had a lower risk of
dying from all causes of death, including coronary heart disease and
cardiovascular disease, than people with low levels of fitness, Japanese
researchers said in Wednesday's issue of JAMA, the Journal of the American
Dr. Satoru Kodama of the University of Tsukuba Institute of Clinical
Medicine, in Ibaraki, Japan, and colleagues analyzed data from 33 previous
studies including more than 100,000 participants with average ages ranging
from 37 to 57 to assess the maximum aerobic capacity of participants and
their overall health.
"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 study's authors wrote.
The researchers suggested men around 50 years of age should be able to walk
continuously at 6.4 kilometres per hour (four miles per hour) and women at
4.8 kilometres per hour (three miles per hour) to prevent coronary heart
Population-based studies have identified a link between
poor physical fitness and incidence of cardiovascular disease in healthy
people, but clinicians do not routinely consider it when estimating future
risk of heart disease, perhaps because the quantitative link is not well
established, the researchers said.
The studies included 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 diseases.
The risk for all-cause mortality was 1.70 times greater among people with
low cardiorespiratory fitness compared with those who scored high on fitness
scales, the researchers said.
People who were less fit were also at 1.50 times higher risk for coronary
heart disease and cardiovascular disease compared with the fittest
In the study, cardiorespiratory fitness was estimated as maximal aerobic
capacity expressed in metabolic equivalent units — defined as the ratio of
intensity of physical activity to that of sitting at rest.
Low cardiorespiratory fitness was defined as less than 7.9 MET, while
intermediate was 7.9 to 10.8 MET, and high was greater than or equal to 10.9
Each 1-MET increase in maximal aerobic capacity was associated with a 13 per
cent decrease in risk of all-cause mortality and a 15 per cent lowering in
risk of both coronary heart disease and cardiovascular disease, the
A 1-MET higher level of maximal aerobic capacity is comparable to losing
seven centimetres in waist circumference in men.
The review may have misclassified cardiorespiratory fitness since
definitions varied between studies, the researchers noted.
They suggested testing whether improving cardiovascular fitness through
exercise actually reduces risk of mortality and coronary heart disease in a
The study was supported by the Japan Society for the Promotion of Science
and Japan's Ministry of Health, Labor and Welfare.