Less fit adults need 30-50 more minutes of weekly exercise to gain the same cardiovascular benefit as the fittest, study finds
A new study based on the UK Biobank, tracking weekly exercise patterns in more than 17,000 adults, has found that those in the lowest cardiovascular fitness band need 30 to 50 more minutes of weekly exercise to reach the same health benefit as those in the highest band. Reported by the Guardian, the study calls for fine-tuning of the classic "150 minutes of moderate-intensity activity per week" guideline.
The study first put participants through a cycling-ergometer test to measure estimated maximum oxygen uptake (VO2 max), then attached an activity tracker for a week to record real-world exercise patterns. These two measurements produced two data sets for each participant: an initial cardiovascular fitness band and a typical weekly activity volume.
Analysis showed that, for adults in the lowest fitness band, an extra 30 minutes of weekly activity produced a clear improvement in cardiovascular risk markers. Those in the highest fitness band achieved a similar improvement with just over 20 minutes of activity. The gap is clinically meaningful and lays the ground for a new personalisation debate in public health advice.
The authors attribute the pattern to a physiological loop. Less fit people begin with lower baseline efficiency in the cardiovascular and respiratory systems; the heart-rate control and mitochondrial renewal gains per session amount to a smaller proportion of fitness improvement than for the already-fit. Equal benefit therefore requires more total effort.
International expert response has been mixed. King's College London epidemiologist Prof. Sarah Hughes, who was not involved in the study, said the findings "measure something that has long been intuited in behavioural health advice." Another expert, Cambridge University's Dr Tom Reynolds, found certain aspects of the study "misguided" — particularly the 10-15 percent error margin in activity trackers, which creates uncertainty in the additional-minutes calculation for the least fit.
The data set has limits because the UK Biobank focuses on adults aged 40-69, leaving questions about generalising to younger age groups. The majority of participants are also white and British, leaving open the question of whether the results would hold in other ethnic backgrounds or different lower-income communities.
The most actionable clinical message is the recommendation that physicians and physiotherapists prioritise individual fitness assessments and tailor exercise prescriptions accordingly. The NHS and the British Association of Sport and Exercise Medicine (BASEM) are planning guideline updates along these lines for next year; the US Centers for Disease Control and Prevention (CDC) is opting to keep the existing 150-minute recommendation in place.
Another important public-health finding is the study's socioeconomic distribution analysis. Adults in the lowest fitness band, on average, live in lower-income neighbourhoods; opportunities to exercise (safe walking routes, free sports facilities, flexible work hours) are also more limited in these communities. The authors offer a reading that foregrounds structural policy responses rather than individual responsibility.
For future work the team plans to combine wearable data with calorie tracking and sleep patterns to develop a broader personalised exercise model. The lowest-band participants will also be followed annually; the long-term impact of additional minutes on mortality and chronic disease incidence will be tested.
The Guardian's report offers readers a simple practical takeaway from the science: the 150-minute weekly guideline remains a good starting point, but stretching that figure to fit the individual's baseline fitness may produce more clinically useful results. Wider use of personalised exercise prescriptions could be an important step in closing the gap left by past one-size-fits-all advice.