It isn't science and is often exploited but it has led to big public health wins, like showing that cigarettes and alcohol cause cancer - instances were human clinical trials would be unethical. Recommendations like not adding salt or not eating eggs became fads because epidemiologists claimed it and media highlighted it, the same way the Mediterranean Diet and buying organic food did. There are so many confounders scientists throw up their hands and walk away but corporations exploit it to billions of dollars in revenue.
One recommendation that has survived all challenges is that moving is good. There is no hard number, like 10,000 steps, as with BMI and salt that is a population level average that has no clinical relevance, but persistence matters. And speed is also linked to better outcomes, though that could obviously be because people in better shape walk faster after years of training.
Credit: Joan Sorolla/Flickr, CC BY
A new (not yet public) analysis went beyond believing what people claim they ate, epidemiologists looked at the heart attacks of 32,192 people between 2013 and 2015 in the UK Biobank study, which is a consortium funded by various corporations and individuals, Medical Research Council, and Wellcome. It is not representative of the UK population, it is mostly healthier, wealthier white people and the time they were known to wear the devices was short, so results are only EXPLORATORY, like all epidemiology, not science.
The subset the authors looked at people enrolled who had high blood pressure and agreed to wear an accelerometer for seven consecutive days to measure how far and how fast they walked. Participant outcomes for nearly eight years provided the demographers with data for 283,001 person-years. Data showed 1,935 cases of heart problems or stroke but walking faster was less likely to result in a negative outcome; 80 steps per minute had an increased positive effect. After 2,000 steps, each additional 1,000 reduced risk of a heart attack while over 10,000 was also correlated to lower risk of stroke. Like cancer, heart failure is coming for us all eventually but a reduced absolute risk of 10.4 strokes per 10,000 person-years before dying just by walking is a high-reward way to improve your chances.
That may not seem meaningful because absolute risk doesn't mean much for you individually - you won't live for 10,000 years - but if you walk with two friends and it means one fewer heart attack among you, that is worthwhile relative risk.
The authors found that even if you don't have high blood pressure, and 20% of the measured world door or are on their way to it, people who walked more had a nearly 25% lower risk of stroke.
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