Less fit need more exercise for same heart benefits, study finds

People who are the least fit need to exercise 30-50 minutes more per week than the fittest to achieve the same reduction in cardiovascular risk, according to a new study.

Researchers analyzed data from more than 17,000 British adults participating in the UK Biobank study. Each participant completed a cycle test to measure baseline cardiorespiratory fitness, expressed as estimated VO2 max, and wore a fitness tracker for one week to record typical exercise levels.

The adults, aged 40 to 69, were tracked for an average of eight years, during which more than 1,200 cardiovascular incidents occurred, including heart attack, atrial fibrillation, stroke and heart failure.

The NHS currently advises adults to engage in at least 150 minutes of moderate to vigorous physical activity each week, such as brisk walking, cycling or running.

The study, published in the British Journal of Sports Medicine, found that meeting this guideline of two and a half hours of exercise was associated with an 8% to 9% reduction in cardiovascular risk.

“Given that large proportions of the population do not meet even this benchmark, the primary public health message remains straightforward: achieving 150 minutes per week of moderate to vigorous activity delivers meaningful cardiovascular protection regardless of fitness level,” the authors conclude.

The research also calculated that more exercise lowered the risk further, but those with the lowest fitness needed about 30 to 50 extra minutes of exercise per week to obtain the same benefits as the fittest.

To achieve a 20% reduced risk, the least fit needed to do 370 minutes of moderate to vigorous physical activity per week, while those with the highest fitness needed only 340 minutes.

To reduce the odds of cardiovascular events by more than 30%, the least fit would need to do more than 10 hours, or 610 minutes, while the most fit would have to do just over nine hours, or 560 minutes.

“This finding highlights the steeper challenge faced by deconditioned populations,” the research concludes.

“Current moderate-to-vigorous physical activity guidelines provide a universal but modest safety margin, whereas optimal cardiovascular protection may require substantially higher activity volumes.”

“Future guidelines and implementation strategies may need to differentiate between the minimal moderate-to-vigorous physical activity volume required for a basic safety margin and the substantially higher volumes necessary for optimal cardiovascular risk reduction.”

The findings appear to challenge previous research, which found that walking only 4,000 steps a day still reduced older people’s risk of dying early by about a quarter.

But experts said recommending more than nine hours of exercise per week was “misguided.”

Aiden Doherty, professor of biomedical informatics at the University of Oxford, said: “We can’t give much weight to the figure of 560-610 minutes of exercise a week.”

“Clearly there will be cardiovascular benefit for people who are able to do (more than) 1 hour 20 minutes of moderate-to-vigorous intensity physical activity a day but this is not a sensible public health message.”

“The public should continue to aim for at least 150 minutes of moderate to vigorous intensity of physical activity a week; more is better; every move counts.”

Responding to the findings, a Sport England spokesperson said that increasing activity levels was vital for keeping people healthier for longer: “Emerging research like this reinforces the importance of helping more people be active, more often.”

“Sport England’s own research shows activity relieves healthcare issues for both individuals and the NHS, preventing 1.3 million cases of depression, 600,000 of diabetes and 57,000 of dementia.”