CATEGORY: IMMUNE HEALTH
If you want one more reason that regular movement matters, a large study from Sweden offers a striking one: adults who were even modestly physically active were less likely to be hospitalized with a serious infection, and less likely to die from one, than those who rarely exercised. The protection showed up at surprisingly low levels of activity, roughly an hour of exercise a week or a short daily walk.1
What the Study Found
The researchers tracked serious infections and sepsis — a life-threatening, runaway reaction of the immune system (your body’s defense network against germs) to an infection that can injure your own organs. Compared with people who exercised less than an hour a week, those who managed about an hour weekly had roughly 7% lower risk of a first serious infection, and about 13% lower risk of dying from infection or sepsis. Doing a little more helped a little more: people active around two to three hours a week were about 20% less likely to end up in an intensive care unit, the hospital ward for the most critically ill. A short daily walk of under 20 minutes was linked to a drop in infection risk similar to an hour of structured exercise. Notably, the benefit rose with activity and then leveled off, so the gains came mostly from moving at all rather than from training hard.
How the Study Worked
The findings come from nearly 65,000 middle-aged and older Swedish adults who filled out detailed lifestyle questionnaires in the late 1990s, describing how much they exercised, walked, cycled, and moved at work and at home. Researchers then followed them for more than two decades through Sweden’s national health registers, which record hospital admissions, intensive-care stays, and causes of death. By linking each person’s reported activity to whether they were later hospitalized for infection, admitted to intensive care, or died of sepsis, the team could compare infection outcomes across activity levels. Over the long follow-up, more than 26,000 people had a serious infection and about 4,700 died from one, giving the researchers a large base of events to analyze.
Why Movement May Bolster Your Defenses
Exactly why activity tracks with fewer severe infections is not settled, but researchers point to several plausible mechanisms. Regular movement is associated with lower chronic inflammation — a persistent, low-grade activation of the immune system that, over years, can wear down its ability to respond to genuine threats. Exercise also appears to help immune cells circulate through the body more efficiently, so they can patrol for and reach invading germs. And staying active is linked to healthier lungs, blood vessels, and body weight, all of which may make it harder for an ordinary infection to spiral into something life-threatening.
Association, Not Proof
This was an observational study, meaning it can show that activity and lower infection risk travel together, but it cannot prove that one causes the other. People who are already unwell often move less, which can make exercise look more protective than it truly is. Activity was also self-reported and measured only once, years before most infections occurred. Even so, the sheer size of the group, the long follow-up, and the consistent, step-by-step pattern — more activity linked to lower risk — make the association difficult to dismiss.
Key Takeaways
- Even light regular activity — about an hour of exercise a week, or a short daily walk — was associated with a lower risk of serious infection and of dying from infection or sepsis.
- The benefit appeared at modest activity levels and then leveled off, suggesting the biggest gains may come from moving at all rather than from intense training.
- Because this was an observational study, it shows an association, not proof that exercise prevents infection.
- If you are weighing how activity fits your health — especially with a chronic condition or a weakened immune system — your own doctor can help you find a level that is safe and realistic for you.
References
- Stattin K, Eriksson M, Frithiof R, Kawati R, Hultstrom M, Lipcsey M. Physical activity is associated with a lower risk of contracting and dying in infection and sepsis: a Swedish population-based cohort study. Critical Care. 2024;28(1):98. link