The short version
- Harvard researchers tracked 70,725 women and 40,742 men who were free of major chronic disease at the start, using the Nurses’ Health Study and the Health Professionals Follow-Up Study.
- Over about 2.4 million person-years, 38,847 people died.
- People who consistently did the widest variety of activities had a 19 percent lower rate of death from any cause than those who did the narrowest, after accounting for how much they exercised overall.
- Walking was tied to one of the largest drops of any single activity. Swimming showed no measurable link at all.
- Published in BMJ Medicine on 20 January 2026, DOI 10.1136/bmjmed-2025-001513.
What was actually measured
Not intensity. Not step counts. The thing this study put at the centre was variety, defined plainly as the number of different activities a person did on a regular basis. Walking, running, cycling, tennis, swimming, weight training, stairs, and so on. Someone who only walked scored low on variety. Someone who walked, lifted, and played tennis scored high, even if the walker logged more total minutes.
That framing is the whole point, and it is what makes the result worth a second look. The researchers were not asking whether exercise helps. We have known that for decades. They were asking whether a mix beats a single habit, holding the total amount roughly constant.
The number that carries the story
Compare the highest-variety group to the lowest. All-cause death rates ran 19 percent lower. Break it out by cause and the gap held across the board: 13 to 41 percent lower for heart disease, cancer, respiratory disease, and other causes. Those are not small differences in a population of this size, spread over three decades and nearly 39,000 deaths.
Now the single activities, comparing the most active to the least. Most landed close together. Walking came in at a hazard ratio of 0.83, meaning roughly a 17 percent lower death rate. Tennis or squash, 0.85. Rowing and calisthenics, 0.86. Weight training and running, 0.87. Climbing stairs, 0.90. Cycling, 0.96, a smaller link.
And swimming: 1.01. No measurable benefit in this data.
Why walking beating swimming should make you cautious
Swimming is excellent exercise. If a study says it did nothing for mortality while walking cut death rates by a sixth, the honest reaction is not “stop swimming.” It is “these are averages, and averages hide who is doing the activity.”
Walking is what almost everyone can do, including frailer people who are still walking precisely because they are doing okay. Swimming in these cohorts may have been a narrower, quirkier group. The activity-by-activity numbers are the softest part of the paper. Read them as texture, not as a leaderboard telling you which sport to pick.
The bias nobody can wave away
Here is the problem sitting under the headline. People who play three or four different sports are, on average, not just more varied exercisers. They are more likely to have spare time, money, safe places to move, and a body that already cooperates. All of those independently predict living longer.
Dr Andrew Scott at the University of Portsmouth put it directly: people with the time, opportunity and resources to do varied activities tend to live well in other ways too. So some of that 19 percent is almost certainly variety acting as a marker for an already-advantaged, already-healthy life, not variety itself doing the work. An observational study cannot cut that knot. Only a trial that randomly assigns people to varied versus single exercise could, and no such trial exists.
So take a position on it: variety is probably part real and part mirror. The biological case for using more muscle groups and movement patterns is reasonable. The claim that mixing it up is independently adding years, on its own, is not something this design can prove.
The honest gaps
- Observational only. It shows association, not cause. Experts including Prof Anna Whittaker at Stirling flagged unmeasured confounders and possible reverse causation.
- Activity was self-reported on questionnaires. Prof Tom Yates at Leicester noted that self-report introduces error and, if anything, tends to understate real links.
- The cohorts were nurses and health professionals, a group that is not representative of everyone. Generalising to other populations is untested here.
- The analysis stopped measuring activity once people fell ill, so it cannot say whether the pattern holds after a diagnosis.
- The single-activity numbers, swimming especially, are fragile and should not be read as ranking sports.
What to do with this
You do not need a gym membership or a new sport to act on this. The practical read is boring and free: keep moving in more than one way. Walk, and add something that uses your arms or your balance or a bit of strength. If you already do one thing you enjoy and will actually keep doing, that consistency matters more than chasing variety for its own sake.
The advice costs nothing and carries almost no downside, which is the one thing you can say cleanly even when the causal story is murky.
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Sources:
- BMJ Medicine, “Physical activity types, variety, and mortality: results from two prospective cohort studies” (https://doi.org/10.1136/bmjmed-2025-001513)
- BMJ Group, “Mix of different types of physical activity may be best for longer life” (https://bmjgroup.com/mix-of-different-types-of-physical-activity-may-be-best-for-longer-life/)
- Science Media Centre, “Expert reaction to types of physical activity and mortality” (https://www.sciencemediacentre.org/expert-reaction-to-types-of-physical-activity-and-mortality/)
Disclaimer: This article is for general information only and does not constitute medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider about any medical condition or before making health decisions.