A large UK Biobank study tracked more than 17,000 middle-aged and older adults who wore wrist accelerometers and had their fitness estimated on an exercise bike. Over roughly eight years it mapped how the combination of measured exercise and cardiorespiratory fitness relates to heart disease. The headline result is sobering for anyone who treats the familiar 150 minutes per week target as a finish line. Meeting that guideline was linked to only about an 8 to 9 percent lower risk of cardiovascular disease. Cutting risk by 30 percent appeared to require roughly 560 to 610 minutes per week, three to four times the minimum. Fitness itself carried an independent protective signal, and a genetic analysis pointed toward higher fitness lowering heart failure risk in particular.
For two decades the public health message on exercise has been reassuringly simple: get 150 minutes of moderate-to-vigorous activity a week and your heart will thank you. A new analysis in the British Journal of Sports Medicine suggests that message is true but oversells how much the minimum actually delivers.
Researchers led by a team at Macao Polytechnic University used the UK Biobank, drawing on 17,088 participants who wore research-grade wrist accelerometers for a week and who also completed a submaximal cycling test to estimate their maximal oxygen uptake, the gold-standard index of cardiorespiratory fitness. Rather than looking at exercise or fitness in isolation, as most previous work has done, they modelled the two together as a joint dose-response surface and watched who developed atrial fibrillation, heart attack, heart failure or stroke over a median of 7.85 years.
The big idea is that the standard guideline is a floor, not a target. Hitting 150 minutes a week was associated with a hazard ratio of about 0.91 to 0.92, an 8 to 9 percent reduction in cardiovascular risk, and that modest benefit held remarkably steady whether a person was unfit or highly fit. To reach the kind of protection that people often assume the guideline provides, a 20 percent reduction, participants needed roughly 340 to 370 minutes a week. For a 30 percent reduction the figure climbed to roughly 560 to 610 minutes, close to an hour and a half a day.
There is an important nuance behind the modest headline number. Earlier studies that reported 20 to 30 percent risk reductions at the guideline dose mostly relied on self-reported activity and did not separately account for fitness. Because this study statistically strips out fitness, its 8 to 9 percent figure captures the effect of the behaviour alone, isolated from the physiological reserve that regular activity slowly builds. In other words the guideline probably does more than 8 percent in the real world, because sustained activity also raises fitness over time, and fitness carries its own protection.
The authors also ran a Mendelian randomisation analysis, using genetic variants as natural randomisers to probe causality. Genetically higher fitness was tied to lower heart failure risk, while genetic signals for activity itself were weaker and less consistent, a familiar pattern given how hard habitual behaviour is to capture with genes. The practical takeaway is a fitness-calibrated prescription: the minimum keeps you safe, but real cardiovascular gains demand substantially more.
Actionable Insights
The single most useful lesson here is a recalibration of expectations. Think of the 150 minutes a week guideline as clearing a low bar rather than winning the race. In this study, hitting that target was linked to only about an 8 to 9 percent lower chance of a serious heart problem. To gauge how big that is, researchers use a standard yardstick that rates effects as negligible, small, medium or large. This one lands at negligible. That does not make the minimum pointless. It is a floor that keeps you out of the highest-risk zone, not a target that delivers big protection.
If you want a real reduction, the pattern is simple: more is more. Cutting risk by 20 percent lined up with roughly 340 to 370 minutes a week. Cutting it by 30 percent took roughly 560 to 610 minutes, which works out to about 80 to 90 minutes a day. The payoff keeps growing as you do more, but even at the high end the effect stays in the small range on that same yardstick. Small is still worth having, especially when it is spread across millions of people, but no single dose here is a magic bullet.
Fitness counts on its own, separately from how much you move. People with higher measured fitness had lower risk regardless of their exercise minutes, on the order of about 10 percent lower risk for a meaningful step up in fitness. And starting out less fit costs you: those individuals needed roughly 30 to 50 more minutes a week than fitter people to earn the same relative benefit. The practical message is to treat 150 minutes as your entry point, push toward much higher weekly totals if you can, and aim to actually raise your fitness over time, not just log the minutes.
Context and Source
- Open access paper: Joint non-linear dose-response associations of device-measured physical activity and cardiorespiratory fitness with cardiovascular disease: a cohort and Mendelian randomisation study.
- Authors and institutions: Zhide Liang and colleagues. Lead institution is the Faculty of Health Sciences and Sports, Macao Polytechnic University, Macao, China, with co-authors from Hainan Normal University, Guangdong University of Foreign Studies, Hainan Medical University and Tsinghua University.
- Country: China (data drawn from the UK Biobank cohort in the United Kingdom).
- Journal: British Journal of Sports Medicine (BMJ Group).
- Impact evaluation: The impact score of this journal is 16.2 (2024 Journal Impact Factor; the 2025 value released in mid-2026 is 15.5), evaluated against a typical high-end range of 0 to 60+ for top general science, therefore this is a High impact journal.
