For years, millions of people across India and the world have lived with a comforting belief — that a short morning walk, a few evening rounds in the park or 150 minutes of weekly exercise are enough to keep the heart safe. But a large new international study is now questioning that long-accepted formula and warning that the human heart may actually need nearly four times more physical activity for meaningful protection against strokes and heart attacks.

The findings, published online in the British Journal of Sports Medicine, suggest adults may need between 560 and 610 minutes of moderate to vigorous physical activity every week to achieve a substantial reduction in cardiovascular risk. That is roughly 10 hours weekly — far above current public health recommendations advising at least 150 minutes of exercise.

Researchers from Macao Polytechnic University analysed health data from 17,088 participants enrolled in the UK Biobank study between 2013 and 2015. Participants, whose average age was 57 and of whom 56% were women, wore wrist-based activity trackers continuously for seven days while also undergoing cycle-based fitness testing to estimate their VO2 max — a scientific measure of how efficiently the body uses oxygen during exercise.

In plain language, VO? max is the body’s “lung-to-life pipeline". It measures how effectively the heart, lungs and muscles work together to push oxygen into the bloodstream and keep the body moving. A stronger pipeline means the body spends less effort protecting itself. A weaker one means the heart struggles harder under stress.

The researchers tracked participants for nearly 7.8 years. During that period, 1,233 cardiovascular events were recorded, including heart rhythm disorders known as atrial fibrillation, heart attacks, heart failures, and strokes.

What shocked scientists was how little protection the globally accepted 150-minute exercise target actually delivered.

People who achieved that level saw only an 8–9% reduction in cardiovascular risk. The real “protective zone" – defined in the study as more than 30% lower risk of major cardiovascular events – appeared only among those doing between 560 and 610 minutes of moderate-to-vigorous activity weekly. Yet only 12% of participants managed to reach that level.

The findings are likely to trigger uncomfortable questions for modern urban societies built around chairs, screens and traffic jams.

Across Indian cities, office workers often spend 8 to 10 hours sitting before attempting a quick walk to “balance” the damage. Cardiologists have long been warned that prolonged inactivity slows metabolism, weakens circulation, and silently strains the heart. This new study adds to growing evidence that the body may need sustained, repeated movement — not occasional effort — to maintain cardiovascular resilience.

The research also revealed what experts described as a hidden “fitness inequality". People with lower cardiorespiratory fitness needed even more exercise to gain the same protection as fitter individuals. For example, someone with poor fitness needed around 370 minutes of weekly activity to achieve a 20% risk reduction, compared with 340 minutes for highly fit individuals.

“This finding highlights the steeper challenge faced by deconditioned populations,” the researchers wrote.

The study further suggested that future exercise guidelines may need to abandon the old “one-size-fits-all” approach. A young athlete and a sedentary office worker may not benefit equally from the same 20-minute walk.

Scientists cautioned that the research was observational and could not prove direct cause and effect. They also acknowledged that the study population may have been healthier than the general public and that lighter activity and sedentary time were not fully measured. Still, the scale of the findings is already intensifying debate in global preventive medicine circles.

Many experts increasingly believe the era of counting steps alone may be ending. The focus is shifting towards intensity, oxygen efficiency and endurance. In simple terms, the heart becomes stronger only if the body feels challenged.

For ordinary families, the message is unsettlingly simple. The daily stroll once treated like a magic shield may only be a small beginning. Researchers now suggest that real medicine could demand far more sweat, movement, and consistency than previously believed. In a world designed for sitting, the human heart still appears desperately built for motion.