Washington DC, Jan 17(DC): According to a recent study, poor cardio respiratory fitness could increase the risk of a future heart attack, even if there are no symptoms of a lifestyle illness today.

The results of the study have been published in 'European Heart Journal'.

"We found a strong link between higher fitness levels and a lower risk of heart attack and angina pectoris over the nine years following the measurements that were taken," said researcher Bjarne Nes.

"Even among people who seem to be healthy, the top 25 per cent of the fit individuals actually have only half as high a risk as the least fit 25 per cent," Nes added.

Between 2006 and 2008, the researchers measured the cardio respiratory fitness of 4527 men and women who participated in the HUNT3 population-based health survey. None of the subjects had cardiovascular disease, cancer or high blood pressure, and most were considered to be at low risk of cardiovascular disease for the next ten years.

Nevertheless, 147 of the participants experienced heart attacks or were diagnosed with angina pectoris by 2017. These diseases signal that the coronary arteries in the heart are narrowed or completely blocked.

The researchers analysed the participants in groups based on their level of fitness in relation to others of the same age and gender. The risk proved to decline steadily as patient fitness increased. The correlation between fitness and cardiovascular risk also held after adjusting for other factors that differed between the most and least fit participants.

Our body uses oxygen to drive metabolic processes that create energy for the muscles. Maximum oxygen absorption is simply the maximum amount of oxygen the body is able to absorb during physical activity. Heart, blood vessel and muscle functioning are all important for oxygen uptake.

"Maximum oxygen uptake is the most precise measure of fitness," explained Bjarne Nes.

"We know that patients with low oxygen uptake are at increased risk of premature death and cardiovascular disease. Our study shows that poorer fitness is an independent risk factor for coronary artery disease, even among healthy women and men who are relatively fit," added Nes.

The study suggests that even a small increase in fitness can significantly improve health. For each increase of 3.5 fitness points, the risk of heart attack or angina decreases by 15 per cent.

Even if you never get in such good shape that you can say you have optimal protection, the study shows that participants' risk was lower the more fit they were.

"There is apparently no upper limit for training when it comes to the beneficial effects for the heart," wrote British Professor Sanjay Sharma.

The researchers stated that we can't do much about our genes, but we can change our exercise habits. The researchers believe it may be useful for doctors to use fitness measurements when assessing their patients' health risks.

"Fitness testing can motivate patients to get into better shape over time, and it focuses on health promotion rather than on illness. Although it may be inconvenient and difficult to measure oxygen uptake at the doctor's office, some simple and relatively accurate calculators exist that can provide a good estimate of fitness and disease risk," the researchers noted.