How Trailly uses AI
Effective 1 September 2026. Version 2026-09-01.
Trailly is the AI coach inside Trailwise. This page explains, in plain words, what it is, what it does with your data, where it stops, and what it is not. It exists because the law asks for transparency about AI and because you deserve to know what is talking to you.
1. You are talking to an AI
Every message from Trailly, the daily call, the weekly digest, the coach digest for your coach and every generated plan are produced by an artificial intelligence, not by a person. Each one carries the mark "Written by AI". Nobody at Trailwise reads your conversations unless you ask for support and share them.
2. What Trailly is built on
Trailly combines two things. A rule-based engine, written and reviewed by people, calculates your scores, load, readiness and plan from your data; those rules decide, and they are the same for everyone. A large language model, provided by Anthropic and run on our behalf, then explains what the engine found, answers your questions and writes the plan in words. The model does not overrule the engine, and the safety rules (for example around low energy availability, pain or return from illness) are written and reviewed by people, never generated by the model.
3. What data Trailly reads
Trailly reads what you have connected, logged and written: training and recovery data, health and body metrics, check-ins, nutrition, races, documents you uploaded and your earlier conversations. It keeps a coaching memory of facts you told it so that it does not ask twice. For each question, only the data needed to answer it is sent to the model, over an encrypted connection.
4. What happens to that data
Anthropic processes your data under a contract that forbids using it to train or improve models, and retains it only as long as needed to answer, with a short retention for abuse monitoring as described on the subprocessors page. Trailwise does not train any model on your data, and does not use one athlete’s data to coach another. Data from Strava is used only as input for your own coaching, in line with the Strava API agreement, and never for training any model.
5. What Trailly is not
Trailly is not a doctor, a physiotherapist or a dietitian, and it cannot examine you. It is not a medical device: it gives general training, recovery and nutrition guidance for healthy adults and it does not diagnose, treat or prevent disease. It is not a substitute for professional advice, and it does not take decisions about you on its own: you can change any plan and ignore any suggestion.
6. Where Trailly is weak
Trailly can be wrong. It cannot see what is not in the data: a hard week at work, a bad night on a sofa, a worry you never wrote down. It is least reliable in your first weeks, when it has little history, and when your data sources disagree. It may sound confident when it should not. When something hurts or feels wrong, trust the person who can look at you, not the text on the screen. The in-app page What Trailly can and cannot do keeps a fuller list.
7. Nutrition guidance
Trailly’s nutrition guidance covers fuelling for training and racing, hydration and general intake targets. It is not a treatment for any condition and it is not for people with a history of disordered eating, who should not follow calorie targets from an app. Trailwise asks screening questions before enabling weight-related targets and closes that feature when the answers call for it.
8. Your choices
You can stop using Trailly at any time and Trailwise will still keep and show your data. You can disconnect any source, delete any value, delete a conversation or your whole account. If a piece of guidance seems wrong, tell us from the feedback button; we read every report.
9. Where to find more
The privacy notice describes the legal basis and your rights. The terms of service describe your and our responsibilities.