This year I did something I never thought I would do. I signed up for my first marathon. I am 47.
When I told people at work, the reaction split right down the middle. Half of them said brilliant, running is the best thing you can do for your health. The other half pulled a face and said something like, you are going to destroy your knees, or, be careful, people drop dead in those races.
So who is right? I went and read the actual research. Did some AI chatting and here's what I found.
First, the good news
The case for running is strong, and it is not small.
A large review pulling together many studies found that runners have roughly a 25 to 30 percent lower risk of dying from any cause than people who do not run. On average, runners tend to live about three years longer than non-runners.
Here is the part that surprised me most. You do not need to run far or fast. In the long-running Copenhagen study, even jogging less than one hour a week, or just once a week, was linked to a meaningful drop in the risk of dying compared to not jogging at all.
On top of the lifespan numbers, regular running is linked to lower blood pressure, stronger bones, better mood, and less depression. It is associated with about 27 percent lower risk of death from any cause and it lifts mood and lowers anxiety. Not bad for something that costs a pair of shoes. At least I thought so in the very beggining.
"But you'll wreck your knees"
This is the one I hear most. And it turns out it is mostly a myth.
It is a widely believed myth, even by some professionals. In one survey, around 29 percent of the public thought frequent running harms the knees, and 54 percent thought the same about long distances, yet more healthcare providers actually saw regular running as good for knee health. (stanford - check the resear done)a
The numbers go the other way. One often-cited comparison followed people for about 15 years and found that arthritis showed up in 10.2 percent of non-runners, only 3.5 percent of recreational runners, and 13.3 percent of competitive runners. Read that again. The people who sat still had nearly three times the arthritis of the recreational runners.
So recreational running seems to protect your joints, not ruin them. Research shows recreational running actually lowers the rate of hip and knee arthritis compared to a sedentary lifestyle, and that includes marathon runners. Even the pounding worry does not hold up well, because the small changes in knee cartilage after a run appear to return to normal within about 90 minutes, which suggests running is a safe activity for healthy knees.
What about your heart? Can you do too much?
For most people, running is excellent for the heart. The worry is about a specific group: men who have done very high volume endurance training for decades. In those lifelong athletes, studies have found a higher chance of high calcium scores in the heart arteries, more plaque, and scarring of the heart muscle compared to less active people.
There is also the heart rhythm angle. By some estimates, middle-aged endurance athletes are about five times more likely than non-athletes to develop atrial fibrillation, which is an irregular, fluttery heartbeat. A recent trial of lifelong athletes also confirmed that even long-term endurance athletes are not immune to fatty build-up in the arteries.
It is not about a weekend runner, and it is not about a 47-year-old doing one sensible marathon build-up.
"Could I drop dead during the race?"
Let me deal with the scary one directly, because it is the fear behind a lot of the warnings.
The odds are genuinely tiny. A large registry found that cardiac arrest happened in about 1 in 184,000 race participants, and death was even rarer at roughly 1 in 259,000. (New England Journal of Medicine)a
And the newest data is encouraging. A 2025 study published in JAMA looked at more than 29 million runners over 23 years and found that the rate of cardiac arrest during races stayed about the same.
To put it in perspective, that risk is lower than many everyday activities. The race is not the danger.
So how much running is the sweet spot?
If more is not always better, what is the target?
The research points to a comfortable amount. The lowest risk of dying showed up at about 1 to 2.5 hours of jogging a week, spread over 2 to 3 sessions, at a steady pace. Beyond that the picture gets debated. Some studies suggest the benefit flattens out at very high volumes, while other large studies found the benefit holds even at the highest amounts of running, although it may trend slightly smaller.
The practical message cuts through all of it: you do not need big mileage or speed to get almost all of the reward. Slow counts. The health benefit barely cares how fast you go.
Starting in midlife (my situation, and maybe yours)
Here is the part that actually got me to sign up.
It is not too late. In fact, runners over 40, the so-called masters runners, are the fastest-growing group in the sport.
And the heart benefits of starting late are real and measurable. A University College London study followed first-time marathoners and found that the training made their arteries behave about four years younger, with the biggest gains in the older, slower runners who had higher blood pressure to start with. The lead researcher put it simply: it appears to never be too late.
Starting later even has advantages. Older beginners are less likely to burn out, tend to be more patient and consistent, and bring life experience to setting and chasing goals.
The catch is you have to train smart. Get a medical check before you ramp up, sleep 7 to 9 hours, take recovery seriously because under-recovery makes injury much more likely, and add some strength work. Build up slowly. Your enthusiasm will be ahead of your tendons. Mine certainly is.
The part I find most exciting: what AI and your watch now know
This is where the science has jumped forward, and it is the reason I am more relaxed about all of it.
Start with one idea that reframes everything. The strongest single predictor of how long you live may not be your weight or your cholesterol. It is your fitness, measured as something called VO2max, which is basically how well your body takes in and uses oxygen. VO2max is the strongest single predictor of longevity and overall health, and low levels are linked to a 2 to 5 times higher risk of early death. It beats the usual suspects, since some researchers find fitness is a stronger predictor of death than smoking, high blood pressure, high cholesterol, or diabetes.
How strong is the effect? One of the largest datasets ever, three quarters of a million people, found that each step up in fitness was linked to a 13 to 15 percent drop in death risk, regardless of age, weight, or sex. And your midlife fitness keeps paying out for decades. The encouraging bit: fitness is trainable at any age, even though it naturally declines by about 5 to 10 percent per decade, it responds well to training even in older adults.
Now the wrist part. Many running watches today estimate your VO2max from your runs, which means your everyday training quietly hands you a number that is tied to how long you might live. One honest warning here: consumer devices push VO2max estimates as if they were clinical grade, but the method behind the number matters, so treat the watch figure as a trend to improve, not gospel.
Then there is the genuinely new stuff. At a major cardiology meeting in November 2025, researchers presented an AI tool that reads the simple single-lead ECG from a smartwatch and can detect structural heart problems such as a weakened pumping ability, damaged valves, or thickened heart muscle. Remember what causes those rare race tragedies: usually a hidden heart problem. A watch that can hint at one before it becomes a headline is a big deal.
The caveat stays the same. This is early, it is not a diagnosis, and a watch does not replace a doctor. But the direction is clear. We are moving from guessing to measuring.
My honest takeaway
For almost everyone, including a 47-year-old me, running is one of the best-value things you can do for a longer, healthier, happier life. The frightening "running is bad for you" stories are mostly about a small group of lifelong, extreme-mileage athletes. They are not about weekend runners, and they are not about a first-time marathoner who builds up sensibly.
So I am lacing up. Slowly. With a check-up first, a gentle plan, and a watch that nags me when I overdo it. The research is on my side, and now the technology is too.
See you at the start line.
Quick note: I am not a doctor, and this is general information from the research, not personal medical advice.