Run or Swim Away from Death: Unexpected Conclusions from Scientists 0 8

We know that physical activity is beneficial. It improves mental health, helps control blood pressure, and reduces the risk of falls in older adults. A large review of 187 randomized studies involving nearly 30,000 people showed that regular exercise reduces mortality risk by about 13%.

But as soon as it comes to specifics, confusion arises. What is better: running or swimming? Hockey or tennis? Strength training or dancing? Can you 'run' away from death faster than you can 'swim' away from it?

A recent publication in BMJ Medicine added fuel to the fire. The article claimed that running is associated with reduced mortality, while swimming is not. It sounds bold. But is it really that straightforward?

Why Such Conclusions Can Be Misleading

Economist and Brown University professor Emily Oster explains in her column for The New York Times why such conclusions require caution.

The ideal way to understand what is truly more effective is through large randomized studies where people are randomly assigned to different training programs. But such projects are expensive, require huge samples, and long years of observation. Moreover, not everyone is willing to engage in sports for years on 'prescription.'

Therefore, most data on the 'best sport' are based on observational studies. Participants are simply asked what they do, and then their health indicators are compared.

And here lies the main problem: correlation does not imply causation.

What the Example of Runners and Swimmers Showed

If you closely examine the data from the BMJ Medicine study, it becomes clear that the issue may not be about running or swimming at all.

Among regularly running participants, about 5% smoked. Among those who swam frequently, it was 11%, which almost corresponds to the national average in the U.S.

Swimmers were more likely to be overweight, have high blood pressure, and have a hereditary predisposition to cancer. One possible explanation is simple: doctors often recommend swimming to people with existing health problems because it is a gentle load without impact on the joints.

Thus, the study speaks more about the types of people choosing different sports than about the exercises themselves.

Not the First Time

Similar stories have happened before.

In a 2019 study published in the U.S. National Library of Medicine, it was claimed that the optimal number is 7,500 steps per day. But those who walked a lot also tended to adhere to other healthy habits: they did not smoke, ate well, and maintained a routine.

In a 2025 article in Nature, it was claimed that one minute of intense activity is equivalent to an hour of light activity. However, the ability to withstand high loads may itself be a sign of good health, rather than a consequence of it.

Once again — a mix-up of cause and effect.

What Is Known for Sure

According to Emily Oster, people love bold conclusions. We want to hear: 'Here is the perfect recipe for longevity.' But the truth is more modest.

We know one thing for sure: regular physical activity that raises heart rate is beneficial.

Randomized studies confirming risk reduction most often focus on about 2.5 hours of moderate activity per week.

As for the answer to the question of what is better — running or swimming — it may remain without a definitive point.

The Main Thing Is Not to Give Up

There is another important factor: commitment. People are much more likely to continue doing what they enjoy and what fits into their lifestyle.

If a person hates running but loves the pool — swimming will benefit them more simply because they won’t quit after a month.

Perhaps the most honest conclusion sounds less spectacular than the headlines: it doesn’t matter whether you run or swim. What matters is that you keep moving. And do it regularly.

Ultimately, it is not a specific sport that prolongs life, but the habit of not stopping.