The research

What this is built on

Furlong's suggestions come from published sports-science research, not from opinion. Every rule the app applies is listed here with the work it rests on.

The same list is in the app, at Settings → About → “The evidence behind this”, and beside “This week, and the plan ahead” on the Today screen. Every source links to the paper itself, not to a summary of it.

Honesty

Where the evidence argues back

The acute-versus-chronic load idea is widely studied and genuinely contested. Researchers disagree about how precisely it predicts anything, and in distance runners specifically the findings are mixed. We think you should know that, so both papers are here too.

This is why the app treats load as a guardrail rather than a verdict. It will tell you a week looks steep given where you are. It will never give you an injury-risk percentage, because that number would be more confident than the research supports.

An app that shows its sources can be argued with.

On how this model was built, and what only became visible once it was drawn: Sorry, Raymond. It is time to take the shell off.

Furlong offers training guidance, not medical advice. It does not diagnose, treat or prevent injury or any medical condition, and it cannot know what is happening in your body. Pain that persists, worsens, or changes how you move belongs to a doctor or physiotherapist, not to an app. Always seek professional advice before starting or changing an exercise programme.