‘Astonishing’: 30 minutes’ exercise a week offsets obesity heart health risk

There is good news for obese people, who are at risk of cardiovascular disease such as stroke and the kind that can cause heart attacks: exercising vigorously for 30 minutes a week can offset that risk.

And for those who find it a challenge to do high-intensity exercise such as running or HIIT – high-intensity interval training – 8 to 9 hours a week of moderate exercise, such as brisk walking or cycling, will have the same effect.

The study, published in the British Journal of Sports Medicine, found obese people with belly fat who exercised did not have a higher risk of cardiovascular disease and death compared to people who did not have fat around their middle.

“It was astonishing for us to see that the risk of high waist circumference was completely overset in those who were the most active,” said researcher Melody Ding, a professor of public health at The University of Sydney.

The research used data from more than 70,000 participants aged 37 to 73, 56 per cent of whom were female.

While exercising at different intensity levels, they wore wrist accelerometers that track motion, orientation and activity levels to measure the link between belly fat and the risk of heart disease.

Vigorous-intensity exercise included that which significantly raised the heart rate, causing the person to be out of breath. This can include:

• running

• swimming

• riding a bicycle fast or on hills

• walking up stairs

• skipping

• aerobics: and

• sports such as football, rugby, netball and hockey.

Moderate-intensity exercise could include:

• walking

• water aerobics

• riding a bicycle

• dancing

• playing doubles tennis.

Light-intensity activities demand an even lower effort, and are often done incidentally, such as strolling or doing housework.

The results suggest physical activity of any intensity can mitigate or even offset the link between belly fat and cardiovascular disease. Those that exercised at moderate to vigorous intensity saw the most benefit, while those who were relatively inactive were more at risk.

While it would appear vigorous exercise such as running may be 15 times more effective than a gentle walk in reducing the risk of cardiovascular disease, Ding cautioned against interpreting the results in this way.

“The take-home message is that everyone should be as active as they can be to their capacity,” she said. “If light intensity is all one can do, it is important to encourage that.”

Lead author Adriano Sánchez-Lastra, of the University of Vigo in Spain, said high- intensity activity should be prioritised when time is limited.

“Incorporating brief bursts of higher-intensity activities into daily life could be more efficient and achievable than aiming for much longer durations of lower-intensity physical activity,” he added.

“We found that approximately 15 times more moderate-to-vigorous physical activity was needed to mitigate the association between [belly fat] with incident cardiovascular disease compared with vigorous physical activity,” said the study authors.

“Weight may not change easily and too much focus on weight could potentially discourage individuals, as well as stigmatising obesity,” said Ding.