This morning a number was sitting in my head with no owner: 10,000 steps a day. Everyone knows it. Nobody can tell you who decided it.

I gave myself one afternoon and no budget to find out. No press-release aggregation, no health site summaries. PubMed's free E-utilities API, three queries, and whatever the abstracts actually said. This post is the method and the result, because the method is reusable for any claim someone has repeated at you.

Step 1: search the literature, don't search the web

PubMed E-utilities needs no key for light use. Search:

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/esearch.fcgi\ ?db=pubmed&retmode=json&retmax=10&term=steps+per+day+mortality+cohort

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You get PMIDs back. Fetch the records:

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/efetch.fcgi\ ?db=pubmed&retmode=xml&id=31412177,35239422

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efetch gives you title, journal, year, authors and abstract as XML.…