About Plain Words

Plain Words is a publication about running data. It exists to answer one question properly — is this normal? — for every metric, benchmark and adjustment a runner meets on a watch or in an app.

It is written by Parth. He builds Inertial, a running app made accuracy-first and privacy-first. The site and the app share one promise: show the working.

The rules

These are not aspirations. A script checks them before a page can be published. A page that fails one does not ship.

• Every number has a source or a stated method. No exceptions. Where there is no good number, the page says there is no good number.
• The method is on the page. Benchmarks, calculators and data notes all carry a "how we got this number" section: the sample size, the window, the filters, and the biases we know about.
• Both units, every time. min/km and min/mi, km and mi, °C and °F. Metric first, imperial in brackets.
• Dates are honest. The "updated" date moves only when the substance moves, and every move has a changelog line saying what changed.
• Nothing is gated. No calculator, chart or table sits behind an email address or an account. Downloads are extra, never the price of the answer.
• No ads, no affiliates, no sponsorship. Nothing on this site is here because someone paid for it to be here.
• Health pages carry a named reviewer and a specific "when to see a professional" section. A wearable metric is never presented as a diagnosis.
• Named humans. Every page has a named author with an author page.

How this is paid for

Inertial makes money from race organisers paying for registrations — never from athletes. The app is free, with no ads, and the parts other apps charge for are not paywalled.

That matters for what you are reading. It removes the two forces that bend most running content. There is no affiliate money, so no reason to steer you toward a shoe. There are no ad slots, so no reason to stretch a 200-word answer into 2,000 words. A page here is as long as the question needs, then stops.

What you will not find here

No shoe reviews. No race news. No training plans sold as products. No articles written to rank for a term nobody asked about.

We also do not publish anything about an individual runner. Aggregate numbers from the app will be opt-in and stripped of location. We will report a figure only where at least fifty distinct runners sit behind it.

Corrections and disagreement

If a number here is wrong, tell us. Tell us too if a source does not say what we claim it says. Corrections get made, and logged in the page's changelog with a date.

Sometimes the evidence itself is contested. In running it often is. The page says so, names both positions, and still gives you a rule you can act on. "The research disagrees" describes the world. It is not an excuse for not answering.