Adults who met the standard public health recommendation of 150 minutes of moderate-to-vigorous activity per week saw their cardiovascular risk fall by 8% to 9%, while a substantial reduction was associated with 560 to 610 minutes a week, according to an analysis of UK Biobank data.
That upper figure is roughly nine to 10 hours weekly, three to four times the current recommendation.
Before anyone reads that as an indictment of the 150-minute standard, one methodological point governs everything else: this study measured activity with wrist-worn devices, and the guideline was built largely on self-reported activity. Those two measurements do not count the same thing, and comparing their numbers directly is where most coverage of this research goes wrong.
The Measurement Problem That Shifts Every Threshold
Self-reported physical activity is systematically inaccurate. People remember structured exercise and forget everything else, and they estimate duration and intensity poorly.
Device measurement captures the opposite pattern. An accelerometer registers brisk walking to a bus stop, carrying groceries upstairs, vigorous housework and pacing during a phone call. It counts every qualifying minute regardless of whether the wearer considered it exercise.
The consequence is that device-measured minutes and self-reported minutes are different currencies. A person who reports 150 minutes weekly may register considerably more on a device. When a study using device measurement finds that 560 minutes are associated with a given benefit, that number cannot be laid alongside a guideline threshold derived from questionnaires as though they were the same scale.
This is why the finding is better read as a statement about dose-response shape than as a new target. The researchers observed that cardiovascular protection scales non-linearly, meaning benefit continues accumulating well past the point where guidelines stop.
The distinction has a practical consequence. A person wearing a fitness tracker who sees 400 active minutes logged in a week has not necessarily been exercising more than someone who reports 150 minutes of deliberate workouts. The device is counting a broader category of movement, and the two figures answer different questions about the same person.
The Study Design and Its Findings
Researchers at Macao Polytechnic University in China analyzed 17,088 UK Biobank participants enrolled between 2013 and 2015, whose activity was recorded by wrist-worn devices over seven consecutive days. Average age was 57, 56% were female and 96% were white. Cardiorespiratory fitness was estimated through a cycle test measuring VO2 max, and the analysis also accounted for smoking, alcohol intake, self-rated health and diet, body mass index, resting heart rate and blood pressure.
Over an average follow-up of 7.8 years, the team recorded 1,233 cardiovascular events including atrial fibrillation, heart attack, heart failure and stroke. The work was published in the British Journal of Sports Medicine in May and paired a cohort analysis with Mendelian randomization, a technique using genetic variants to probe causal relationships.
Fitness level changed the required dose. To reach a 20% reduction in cardiovascular events, participants at the lowest cardiorespiratory fitness needed roughly 370 minutes weekly against about 340 minutes for those at the highest.
The researchers' own conclusion is more measured than most coverage suggested. They say the findings confirm that current guidelines provide a robust universal minimum for cardiovascular protection, while arguing for stratified advice for motivated patients. "Future guidelines may need to differentiate between the minimal moderate to vigorous exercise volume required for a basic safety margin and the substantially higher volumes necessary for optimal cardiovascular risk reduction," they wrote.
The Limits of What This Establishes
This is observational research using a single week of device wear to characterize habitual activity, which assumes that week is representative.
Reverse causation is the central concern in exercise epidemiology. People with undiagnosed early cardiovascular disease move less because they are becoming ill, which makes low activity look more dangerous than it is. The Mendelian randomization component is intended to address this, but it does not eliminate it.
The UK Biobank cohort is also not representative. Participants were 96% white, healthier and wealthier than the general population, with an average age of 57. Findings may not transfer to younger adults or to more diverse populations.
Estimates at the far end of the activity curve necessarily rest on the smaller number of people who reach those volumes, and carry wider uncertainty than the estimates near the guideline threshold. That group may also differ systematically from the rest of the cohort in ways activity measurement does not capture, including occupation, mobility and baseline health.
No guideline body has changed its recommendation in response, and a single observational study would not be expected to produce that.
The Reading That Serves People Rather Than Discourages Them
The genuine risk with this finding is that someone currently doing 20 minutes of walking twice a week reads about nine hours and concludes the effort is pointless.
That is the opposite of what the data show. The steepest gains in nearly all physical activity research occur at the bottom of the curve, moving from sedentary to some activity. The 150-minute threshold produced a measurable 8% to 9% reduction described by the researchers as consistent but modest across fitness levels, which is a real benefit obtained at an achievable dose.
What the analysis adds is that the curve does not flatten where guidelines stop. For someone already comfortably meeting 150 minutes and asking whether more helps, this is evidence that it does.
The fitness finding also cuts against a discouraging reading. Lower fitness requires modestly more time now, but fitness itself improves with training, which means the required dose falls as a person becomes more conditioned.
Anyone with existing heart disease, chest symptoms on exertion, or a long period of inactivity should talk with a clinician before making a substantial jump in training volume rather than scaling up on their own. Increasing weekly volume abruptly raises injury risk, and injury is the most common reason people stop entirely. Older adults face additional considerations, as MedicalDaily reported in coverage of prescribing gaps for people over 65. MedicalDaily has covered how quickly metabolic gains reverse when an intervention stops, a pattern that applies to fitness as much as to medication, and the scale of GLP-1 use now reshaping the same conversations.
Key Questions Answered
What did the analysis find? Meeting the 150-minute weekly guideline was associated with an 8% to 9% reduction in cardiovascular risk. A substantial reduction was associated with 560 to 610 minutes weekly, roughly nine to 10 hours.
Does this mean the 150-minute guideline is wrong? No. The researchers say their findings confirm current guidelines provide a robust universal minimum. The study suggests benefit continues accumulating past that point rather than that the threshold is worthless.
Why can't the two numbers be compared directly? This study used wrist-worn devices, which capture all qualifying activity including incidental movement. Guidelines were built largely on self-reported activity, which people underestimate. The two measurements are different scales.
Does fitness level change how much is needed? Yes. For a 20% risk reduction, participants at the lowest cardiorespiratory fitness needed roughly 370 minutes weekly against about 340 for the fittest.
How strong is the evidence? Observational, using one week of device wear, in a UK Biobank cohort that was 96% white and healthier than the general population. Reverse causation cannot be fully excluded. No guideline body has changed its recommendation.
Should someone doing very little exercise be discouraged? No. The steepest gains in physical activity research occur when moving from sedentary to some activity. Lower fitness also improves with training, which reduces the dose required over time.
Who should check with a clinician first? Anyone with existing heart disease, chest symptoms on exertion, or a long period of inactivity, before making a large increase in training volume.
