RETO

RETO is an iPhone app that plans your training across running, cycling, swimming and strength. Connect your watch or ring, set your goals, and it builds your week from your own data, then keeps adjusting it as you train, sleep and recover.

Anyone training for something: a first 5 km, a personal best, a triathlon, a strength goal, or several at once. You do not need to be an elite athlete or to understand the maths. You need a goal and a watch or ring.

Women's health is part of the plan from day one, and RETO works for every body.

Ask a chatbot to program your squats around your hill repeats and it will give you something that sounds right. RETO knows your Achilles is carrying load from both, how much load it can tolerate, and how much it needs to keep progressing.

A language model never sees your full history. It works from a summary, it can give different answers to the same question, and nobody can check that its output holds up in every case. RETO solves your plan with optimisation: every limit and rule is respected at once, specialists can review those rules, and the same inputs always give the same, explainable answer.

Training is a health decision you make every day, with real consequences when it goes wrong, like injury or RED-S. You would not ask a chatbot to work out a medication dose.

Yes, as the voice, not the brain. AI is good at conversation and explanation, so you can tell RETO “my knee feels a bit off and I have a wedding on Saturday” in plain language, and it explains your plan back to you clearly. The model of your body decides what you actually do.

As AI gets better, RETO gets better too. What a general AI will not have is our model, and the data behind how real bodies respond and adapt.

Most apps pick a plan template and scale it to you, usually for one sport, with cycle tracking (if any) kept to one side.

RETO counts your runs, rides, swims and lifts in one common load currency, tracks the load on each muscle group and tendon, and models fatigue across all of them together. So strength work is planned alongside your running rather than squeezed in around it, and no goal quietly costs another.

Your cycle should not be something you push through or plan around alone. You log your period in the app and, if you wear an Oura ring, RETO uses your overnight skin temperature to detect ovulation. It learns your own pattern over time rather than assuming a textbook 28 days.

The plan then works with that pattern, so the hardest week of training does not have to land on the hardest week of the month, and you can train with confidence all month.

Most sports science and most training tech were built around men, and women's bodies are not just smaller men. Cycle phase, iron, energy availability and hormonal health all change what your body can absorb. When they are ignored, the warning signs get missed, often until there is an injury, burnout or RED-S.

RETO treats them as planning inputs from the start, for everyone who trains.

Cycle tracking is optional, and RETO plans well without it. Hormonal contraception is handled explicitly, and because RETO learns from your own data rather than a fixed calendar, irregular cycles are expected rather than treated as errors.

RETO is a training app, not a medical device. It does not diagnose conditions and it is not a form of contraception. If something looks off, talk to your doctor.

An iPhone and a device that records your training and recovery. RETO works with Garmin and Oura today, and can push your corrected sessions to Strava. More devices will follow.

Strength sessions are logged in the app itself, set by set.

The plan rewrites itself from where you actually are, not where it said you should be. Weekly targets are held steady so the goalposts do not move on you mid-week, and when fatigue climbs faster than fitness the plan eases off.

RETO is built to the GDPR. Your data is stored in the EU, used only to plan and explain your training, and never sold or shared for advertising. Health data such as your cycle is special category data under the GDPR, so it is processed only with your explicit consent, kept separately under that consent, and erased in full if you withdraw it.

You can see, export, correct or delete your data at any time, and withdraw any consent as easily as you gave it. The full detail is in our privacy policy.

The app is built, and the beta opens on iPhone in November 2026 with limited spots. Join the waitlist and we will let you know when it is your turn. One email, nothing else.