Teenage men who are physically fit are less likely to develop heart-related illnesses later in life, according to a new study MedPage Today reported.

Researchers from Umea University in Sweden found that men who had lower fitness levels before entering "mandatory military service" at 18 were more likely to suffer a heart attack within 30 to 40 years.

"Overall these findings suggest that high aerobic fitness in late adolescence may reduce the risk of MI later in life, although high cardiovascular fitness appears not to fully compensate for overweight or obesity with respect to this risk," researchers wrote in the study.

After analyzing and monitoring the data of more than 700,000 men for an average of 34 years, researchers concluded that men who were more aerobically fit at 18 were less likely to suffer a heart attack, MedPage Today reported.

They also found that every 15 percent increase in aerobic fitness was associated with an 18 percent reduced risk of suffering from a heart attack 30 years later. They also discovered that 18-year-olds who regularly undertook cardiovascular training, such as running, cycling and swimming, reduced their risk of a heart attack later in life by 35 percent.

Researchers noted that regardless of fitness levels, obese men continued to have higher rates of heart attacks compared to their leaner counterparts.

"Being very fit does not appear to fully compensate for being overweight or obese in respect to this risk," Peter Nordstrom of Umea University in Sweden said in a statement. Our study suggests that it's more important not to be overweight or obese than to be fit, but that it's even better to be both fit and a normal weight."

Although the associations between various measures of greater muscle strength and reduced MI risk were weaker, they were still statistically significant, according to researchers.

The study was recently published in the European Heart Journal.