Teen fitness is linked to reduced risk of myocardial infarction

If teenage boys were asked to choose between exercising and playing computer games, the majority would choose computer games. But new research suggests adolescent boys should be more physically active, as low fitness levels may increase their risk of having a heart attack later in life.

This is according to a study published in the European Heart Journal.

A research team from Sweden, led by Prof. Peter Nordström, of Umeå University, analyzed data of 743,498 men. All men were a part of the Swedish armed forces between 1969 and 1984, and underwent a medical examination when they were 18-years-old.

The medical examination involved measuring the participants’ blood pressure, weight, height and muscle strength.

It also measured their aerobic fitness through a cycle test. Cycling resistance was increased by 25 watts a minute until the participants’ were too exhausted to carry on. Their maximum wattage was used for the study.

The research team divided the participants’ results into five groups, ranging from the lowest levels of aerobic fitness to the highest.

All men were followed for an average of 34 years until either the date of death, the date of their first heart attack, or until January 1 2011.

During the follow-up period, there were 7,575 incidences of myocardial infarctions – the equivalent to approximately 1,222 heart attacks per 100,000 men.

High aerobic fitness linked to lower heart attack risk
On comparing aerobic fitness with the participants’ risk of heart attack, the researchers found that men in the lowest aerobic fitness group were 2.1 times more likely to suffer a heart attack later in life compared with men in the highest aerobic fitness group.

The results also revealed that for every 15% increase in aerobic fitness, the men were 18% less likely to have a heart attack. This was after taking factors such as body mass index (BMI) and socioeconomic background into consideration.

Furthermore, the investigators found that men who carried out regular cardiovascular training in late adolescence reduced their risk of heart attack later in life by 35%.

Results dependent on BMI
To analyze how BMI and aerobic fitness combined had an impact on the participants’ risk of heart attack, the researchers separated the men into four groups in line with the World Health Organization’s definitions of BMI.

These were:

Underweight/lean (BMI less than 18.5kg/m2)
Normal weight (BMI between 18.5-25kg/m2)
Overweight (BMI between 25-30kg/m2)
Obese (BMI over 30kg/m2)
Results revealed that the fittest obese men had almost double the risk of heart attack compared with men who were lean but the most unfit. Furthermore, the fittest obese men had almost four times the risk of heart attack compared with the fittest lean men.

Commenting on their findings, Prof. Nordström says:

“Our findings suggest that high aerobic fitness in late adolescence may reduce the risk of heart attack later in life.

However, being very fit does not appear to fully compensate for being overweight or obese in respect to this risk. 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.”

He notes that further research is needed to determine how these findings are clinically relevant, “but given the strong association that we have found,” he adds, “the low cost and easy accessibility of cardiovascular training, and the role of heart disease as a major cause of illness and death worldwide, these results are important with respect to public health.”

Source: Medical news today

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