Exercise Overhype

A new study suggests messaging around exercise can go too far.

This is, truly, a post that makes a case for “have fun, don’t die.”

Post summary

• We’re told exercise is a miracle cure.

• But a new study suggests that exercise research has many issues that muddy the waters.

• The study raises questions about whether exercise improves lifespan and suggests that the benefits of exercise are more nuanced.

• I spoke to the study’s primary author to learn more.

• I’ll also explain how this research, along with a conversation I had with the wise Dr. Trevor Kashey, is guiding my approach to exercise.

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The post

Exercise is good for us. This we know.

But I’ve noticed a new trend online—and even in the medical and academic establishments—where exercise is being pitched as a cure-all, like we can sweat out any disease or problem.

Even the British Medical Journal published a paper calling exercise “The Miracle Cure.”¹

I am, admittedly, part of this trend. I’ve written extensively about the mental, physical, and emotional benefits of moving your body.

But as coverage of exercise has gone mainstream, I’ve started to worry about two things:

1. That we’re overhyping exercise.

2. That in promoting exercise so heavily, we’re missing the other layers of living that contribute to health.

So I was oddly relieved to come across a recent study² that challenges the idea of exercise as miracle cure.

Using new methods, the study suggests that fitness may not be as protective against death as we’ve been told.

Instead of ignoring the findings, I dug in. I am, after all, a journalist and not a cheerleader.

I analyzed the study and called its primary author, Marcel Ballin, Ph.D. He Facetimed me from a park in Sweden. “I was planning to be home for this interview,” he said. “But I missed my bus.”

Here’s what we’ll cover today:

• How the study was conducted and why its methods matter.

• Why exercise may not be a cure-all.

• How new methods in exercise science can give us better information.

• How the study results are improving how I think about exercise.

Let’s roll …

The study

• Section summary: Confounders muddy exercise and longevity data. A new study utilized a powerful dataset and innovative methods to investigate whether confounders are skewing results in exercise and longevity.

Whenever I cover a study, I try to note any possible “confounders.”

Confounders are hidden variables not accounted for in a study that make one thing appear to be caused by another—when really the results could be explained by the hidden variable.³

Exercise studies are loaded with confounders.

If you compare a group of people who exercise to those who don’t, you can safely assume the exercisers are more likely to have many other healthy habits.

They’re more likely to eat healthier, not smoke, and much more. Researchers can control for some of these confounders. But many known confounders are difficult to measure, and there are surely other confounders we’re not aware of.

“So our question was: How confident can we be that the groups are comparable in these observational exercise studies?” Ballin told me. “Are we really comparing people who are similar in all aspects except for fitness? Because if we are not, and the groups also differ in other ways that are affecting both fitness levels and, say, disease and mortality risk, how do we know whether it was the fitness that was protective and not these other factors?”

To answer that, Ballin and his colleagues used a uniquely powerful dataset: The Swedish Military Service Conscription Register.

“It included 90 percent of Swedish men over a few decades and takes many different types of measurements,” said Ballin. “Not only fitness measurements, but also blood pressure, muscular strength, intelligence tests.”

They then pulled from other health registries in Sweden to track the health of the men throughout their lives. “We can track if they died, when they died, and what they died from,” he said.

Next they did something clever: They located the siblings in the group. Instead of comparing random people, they compared brothers who had different fitness levels.

“By comparing brothers, we could control⁴ for all the factors that the siblings shared and better isolate the effects of fitness,” said Ballin.

This gave them roughly 400,000 brothers to compare.

The team then looked at how being fit was linked to premature death from all causes and from three specific causes of early death: heart disease, cancer, and accidents (like car crashes or drowning).

That last category, accidents, was the key to the study.

Dying in an accident has little to do with your fitness level⁵.

So if high fitness was also linked to fewer accidental deaths, that would hint that other factors like wealth, personality, or upbringing were skewing the data.

The finding

• Section summary: The study results suggest that exercise alone may not be as powerful for longevity as we’ve been told.

Unsurprisingly, higher fitness was associated with a lower risk of premature death from all causes, heart disease, and cancer.

But here’s the twist: Fitness was also linked to a lower risk accidental deaths—nearly identically to cancer and heart disease deaths.

Ballin had expected to see some relationship between fitness and accidents, but not a relationship this strong. And not one that mimicked the other causes of death so precisely.

Even after adjusting for all the factors that siblings share—including income, education, and early home environment—the associations remained.

“You’d expect fitness to have a big impact on heart disease,” Ballin said. “That’s supported by both epidemiological and mechanistic studies. But why would fitness cut the risk of, say, being hit by a car or dying from an accidental poisoning in half?”

This suggests that perhaps it’s not fitness alone keeping people alive longer⁶.

“The findings suggest that people who are more fit are different in other important ways beyond just fitness,” Ballin said.

He speculated about what those other factors might be: “They may be more conscientious, have more resources, or live in safer environments. And those differences—not the fitness alone—could be driving much of the (longevity) benefit we observe.”

Most exercise studies don’t catch this nuance. They assume people live longer because they’re fit, when in fact they might just have healthier lives overall.

Researcher Stephan Guyenet, Ph.D., summed it up⁷ like this:

“I've long thought there was probably a lot of confounders in (the association between exercise and mortality), but it's turning out to be larger than I expected.”

• Go deeper: Listen to my conversation with

  Adam Cifu, MD
  on The Cult of the Healthy Lifestyle.

Why it matters

• Section summary: Exercise delivers many benefits. Regarding longevity, however, we should start thinking about who exercise is best for, when, and how—and consider all the other factors that contribute to living longer.

To be clear, Ballin is not saying “don’t exercise.”

“I’m not trying to be a front figure for some anti-exercise movement,” he told me with a laugh. “Exercise has many proven benefits, such as improving quality of life and managing certain conditions. But I do think we need to be more careful and precise in how we talk about it.”

He continued. “For example, a randomized trial just came out suggesting that structured exercise gave survival benefits to a group of people with colon cancer. I was really happy to see that.”

“But with regards to being precise,” he said, “it’s important to note that that study was with a specific population group, and that exercise was being used for secondary prevention⁸. We cannot say that the same intervention would yield similar benefits in, for example, a healthy population. So I think we need to start looking into who exercise helps the most and under what conditions.”

In reality, exercise likely delivers different benefits to different people in different situations.

But that nuance often gets lost in today’s black-and-white health narratives. “I think there are many overstatements,” Ballin told me. “We’re too quick to attribute disease to a lack of exercise. And lots of messages say exercise can protect us from all diseases and is equally large for most outcomes, which is sort of ridiculous. Realistically, exercise is likely more meaningful for certain outcomes and lesser for others.”

Ballin’s study suggests that such claims may rely on overstated or misunderstood data. Worse, these oversimplifications may backfire—especially for people who hate exercise or can’t do it regularly.

“If someone absolutely hates working out, we need to be honest about what they’re really getting from it,” Ballin said. “Maybe they’d be better off using their time in a way they enjoy and still get similar or bigger benefits in other areas of life.”

It also raises questions about public health funding. If the lifespan benefits of exercise are smaller or more context-dependent than we thought, maybe we should get more precise. What types of exercise help who, when, and how? Like that colon cancer study.

The bigger shift in science

• Section summary: New research methods may help us get more targeted with using exercise to extend lifespan.

What made this study unique is that Ballin asked a question about exercise in a different way. And that’s missing from most exercise studies.

“Too often, we keep asking the same question in the same way, with bigger samples,” he said. “But if your method has a blind spot, you’re just throwing darts at the wrong target—with more accuracy.”

He’s part of a movement pushing for what's called triangulation in epidemiology: asking the same question through multiple study designs, each with its own strengths and weaknesses. If you keep getting the same result through different methods, then you can be more confident the results are real.

And his work isn’t the first to raise these questions:

• This study⁹ concluded, “The association between (exercise) and lower all-cause mortality may be largely due to genetic confounding and reverse causality.”

How I’m thinking differently

• Section summary: I outline three ways this data is changing how I think about exercise. I don’t want to lose the nuance, so please read below!

A couple of years ago, I was staying with Dr. Trevor Kashey. I mentioned that I’d been doing a workout I loathed because some research suggested it had longevity benefits.

“What do you care?” he asked. “Let’s say it gives you two extra years. Ok—now you have to subtract all the time you spent doing that shitty workout. Maybe it’s a net negative. And I really don’t think we can say that one specific exercise is going to make you live longer than a form of exercise you actually enjoy.”

And that, I think, is the handle. Exercise is good. For longevity, however, the data doesn’t seem to be strong enough to support hyper-specific exercise recommendations—like X amount of time at Y heart rate for Z sessions each week.

Here’s how this is guiding my thinking:

1. I prioritize exercise I enjoy.
   I no longer suffer through boring “zoned” treadmill protocols because they supposedly extend my life.

2. I look for side benefits.
   For example, trail running gets me into nature and gives me more real-world variability. Exercising with Cousin Tanner—even though I never train as hard—gives me a strong social component. Confounders hurt research, but they can help us.

3. I’ll do workouts I dislike only if they serve a measurable, short-term goal.
   For example, I hate this Burn the Ships workout. But I do it often because it improves my ability to move swiftly and have fun in the outdoors. So I accept the suffering of the workout because it pays off soon outdoors.

What do you think? This is a topic I’m still pondering. Please drop your thoughts in the comments section below.

Have fun, don’t die,

-Michael

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1. Godlee, Fiona. The miracle cure; BMJ 2019; 366:l5605

2. Ballin M, Nordström A, Nordström P, Ahlqvist VH. Cardiorespiratory fitness in adolescence and premature mortality: widespread bias identified using negative control outcomes and sibling comparisons. European Journal of Preventive Cardiology;doi:10.1093/eurjpc/zwaf267. Published online 15 May 2025.

3. Here’s a dumb example: Let’s say a study found that kids who wear bigger shoes are better readers. We might think big shoe size promoted better reading. In reality, the results would likely be from the fact that older kids have bigger feet—and older kids tend to be better readers. Age is the confounder.

4. For example, behavioral, environmental, and genetic confounders.

5. Ballin noted, “I mean, maybe you could argue that having a slightly improved reaction speed from fitness could help you in a car accident,” said Ballin. “But I don’t imagine that would factor into most car crash deaths, and it wouldn’t impact the vast majority of accidental deaths.”

6. The word “alone” is important. Ballin isn’t saying fitness isn’t helpful. He’s asking if fitness and fitness alone leads to longer life.

7. See his X thread here. It spurred a lot of interesting back and forth.

8. I.e., these people had undergone a primary treatment of chemo and radiation.

9. Kankaanpää, A., Tolvanen, A., Joensuu, L. et al. The associations of long-term physical activity in adulthood with later biological ageing and all-cause mortality – a prospective twin study. Eur J Epidemiol 40, 107–122 (2025). https://doi.org/10.1007/s10654-024-01200-x