Comment by starchild3001
3 days ago
The evidence for exercise reducing all-cause mortality is more nuanced than many assume. It's crucial to distinguish between findings from RCTs (Randomized Controlled Trials) and observational studies.
A meta-analysis of RCTs with ~50,000 participants concluded that exercise did not reduce all-cause mortality or incident CVD in older adults or people with chronic conditions [1].
However, for specific high-risk groups, the causal evidence from RCTs is strong. A separate meta-analysis found that for cancer patients and survivors, exercise led to [2]:
- A 24% reduction in mortality risk
- A 48% reduction in recurrence risk
The commonly cited large benefits (e.g., 40% lower mortality) come from observational studies [3]. These are very susceptible to the "healthy user bias" or reverse causation—people who are healthy enough to exercise are already at a lower risk of dying. This makes it difficult to prove the exercise caused the benefit.
So, while exercise is strongly associated with lower mortality, the direct causal evidence for the general population isn't as definitive as it is for specific subgroups like cancer survivors.
[1] https://scholar.google.com/scholar?cluster=10512580439138189...
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