News · Fitness & Exercise
High genetic risk plus few steps tripled heart disease risk
UK Biobank tracked 84,286 people with wrist monitors and genetic scores. Steps and genes acted independently, which means walking helped the genetically unlucky just as much.
Based on a peer-reviewed prospective cohort study in the European Journal of Preventive Cardiology
- Researchers combined wrist-worn accelerometer data with genetic risk scores for 84,286 UK Biobank participants who had no cardiovascular disease at baseline, publishing in the European Journal of Preventive Cardiology.
- Over a median 7.9 years, 4,847 people developed cardiovascular disease.
- Genetic risk was split into low (bottom fifth), moderate (middle three fifths) and high (top fifth); daily steps were measured, not self-reported.
- High genetic risk and low step count were each independently associated with higher risk.
- There was no multiplicative interaction between them (P for interaction = 0.46), meaning genes did not blunt the benefit of walking.
- Compared with low genetic risk and high steps, the combination of high genetic risk and low steps carried nearly triple the risk (HR, 2.81; 95% CI, 2.27-3.46).
- Absolute risk in the reference group was 62 cases per 1,000 people.
- Observational. People who walk more differ from people who walk less in ways a step counter cannot capture.
Anyone with a family history of heart disease has probably wondered whether the effort is worth it. A study in the European Journal of Preventive Cardiology put wrist monitors and genetic scores on the same 84,286 people and answered it directly.
The aim was to investigate whether accelerometer-measured step count is associated with incident cardiovascular disease, independently from genetic risk.
Two measurements, both objective
What distinguishes this from most activity research is that neither variable was self-reported.
The study included UK Biobank participants with valid accelerometer and genetic data and without prevalent CVD at baseline. Activity came from a wrist device rather than a questionnaire, which matters because people consistently overestimate how much they move, and the least active overestimate most.
Genetic risk for CVD was categorised as low (1st fifth), moderate (2nd-4th fifths), and high (5th fifth), with step counts likewise grouped.
Then everyone was followed. Of 84,286 participants, 4,847 developed CVD during follow-up, with a median of 7.9 years.
Both mattered, separately
The headline structure of the result is the important part.
High genetic risk and low step count were independently associated with higher risk of CVD, with no evidence of a multiplicative interaction - the interaction test came back at 0.46, nowhere near suggesting one factor changes the other’s effect.
That single number is the finding. If genes and steps interacted, walking might have helped the genetically fortunate and done less for everyone else. Instead the two behaved like separate contributions.
The stacked comparison
Putting the extremes side by side shows the scale.
Compared with the reference group of low genetic risk and high step count, with an absolute risk of 62 per 1,000, the highest risk of CVD was observed in participants with high genetic risk and low step count, at 2.81 with a range from 2.27 to 3.46.
Nearly triple, comparing the worst combination against the best. Neither factor alone accounts for that; it is both together.
What the result does not license
Independent is not the same as cancelling. Someone at high genetic risk who walks a great deal still carries the genetic component. What they avoid is adding the inactivity component on top. The study is about two contributions being separable, not about one erasing the other.
It is also observational, and that limitation is real here. People who accumulate more steps differ from people who accumulate fewer in ways no wrist device records: they are less likely to have an undiagnosed illness limiting their movement, more likely to be employed, generally better off. Reverse causation is particularly plausible, because early cardiovascular disease reduces activity long before it produces a diagnosis.
UK Biobank is also famously unrepresentative. Participants are healthier, wealthier and overwhelmingly of European ancestry, which matters doubly for a genetic analysis, since polygenic scores transfer poorly across ancestries.
And the accelerometer captured roughly one week of movement, then that week stood in for years of behavior.
Why it is still worth knowing
The authors’ conclusion is appropriately plain: high daily step count was associated with lower CVD risk in individuals with moderate and high genetic risk, indicating that walking should be encouraged for all, especially those predisposed to CVD.
Especially those predisposed is the phrase to take away. The intuition that inherited risk makes effort pointless is common, understandable, and on this evidence backwards. The people with the most genetic risk were not the people for whom walking mattered least.
People also ask
Why does measuring steps with a device matter?
Because self-reported activity is unreliable in a specific direction: people overestimate how much they move, and the overestimate is larger among those who move least. A wrist accelerometer records what actually happened. That removes a bias that has weakened much of the earlier literature linking activity to heart disease.
What does no interaction mean here, and why is it the key finding?
It means genetic risk and step count acted like two separate levers rather than one modifying the other. If there had been an interaction, walking might have helped people with favorable genetics while doing little for those at high genetic risk, which is the pessimistic story people often assume. The data did not support that. Walking was associated with lower risk across genetic strata.
Does this mean exercise cancels out bad genes?
No, and that is a stronger claim than the study supports. Independent means the two contribute separately, not that one erases the other. Someone at high genetic risk who walks a lot still carries their genetic risk; they simply are not also carrying the additional risk that comes with inactivity. The study measures association, not cancellation.
How large is a hazard ratio of 2.81?
Substantial for a lifestyle-and-genetics comparison. It compares the worst combination, high genetic risk with low steps, against the best, low genetic risk with high steps, so it captures both factors stacked. The absolute numbers give better perspective: the reference group saw about 62 cases per 1,000 people over the follow-up period.
How many steps should someone aim for?
This is general information rather than medical advice, and the study grouped people rather than identifying a precise threshold. The wider evidence suggests benefits accumulate well below the popular 10,000 target, with much of the gain appearing between very low and moderate counts. Anyone with a heart condition or who has been inactive for a long time should discuss an activity plan with a clinician before starting.
References
- Birmpili P, Brocklebank L, Portas L, Littlejohns TJ, Doherty A. Joint association of genetic risk and accelerometer-based step count with cardiovascular disease: a UK-Biobank cohort study. European Journal of Preventive Cardiology (2026).
- Centers for Disease Control and Prevention. Physical Activity Basics: Adults.
- National Heart, Lung, and Blood Institute. Heart-Healthy Living.