Study finds that fast walking can reduce lung cancer risk by 50%: A simple health indicator for cancer prevention
Study finds that fast walking can reduce lung cancer risk by 50%: A simple health indicator for cancer prevention
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HKUMed study finds that fast walking can reduce lung cancer risk by 50%: A simple health indicator for cancer prevention - All News - Media - HKU

As always, correlation =|= causation. Walking speed is almost certainly linked to like 15 other good health indicators. Exercise is good for you, and you should do it. But these results do not support the recommendation that fast walking will reduce your chances of lung cancer. These results say that if you already walk fast that you probably have a lower chance of lung cancer. Maybe it is the healthier lungs that allow you to walk faster? Maybe it's a genetic component that makes you walk faster AND reduces your chances of lung cancer. Maybe they fucked up the sample and all of their slow walkers lived downwind of an asbestos plant.
Again, exercise is good for you. Exercise as much as you can. Cannot stress that enough. The health value of exercise is unquestionable and universal, and a lack of exercise is bad for you in every way. Bad science is bad for everyone, though.
i have to wonder if just breathing more protects against lung cancer somehow
Perhaps. Or maybe, people with healthier, more efficient lungs are able to walk faster without breathing heavier. In that case, breathing less might reduce the inhaled carcinogens, reducing the risk of lung cancer.
Looking at the actual research, the conclusions are carefully worded to avoid this sort of reporting.
Probably. Or maybe, people who have healthier lungs don't need to breathe as much to efficiently exchange oxygen for CO2. So maybe breathing less protects against lung cancer by inhaling fewer carcinogens.
There are simply too many confounding variables to control for all of them. Research like this is important, and it's not the researchers' fault. Notice how the conclusions are carefully worded to specifically avoid exactly this sort of news article.