Fitness that fits real life.
KAI Fitness brings gym training and timed HIIT together in one calm, focused app. Ten minutes or a full hour, at home, at the gym or outdoors: log every set, let the intervals run themselves, and keep a routine that survives a busy week.
What the app does
The parts you use most, and what each one is for.
Two ways to train, one app
Timed HIIT on one card, the gym on the other. The week runs along the top, with a dot for every session you have logged. You pick one and start: that is the whole decision.
Keep count, keep your flow
Every set with its reps and its weight, ticked off as you go. The rest timer sits at the bottom and starts on its own, so you never have to leave the screen you are working on.
The numbers, worked out mid-lift
Estimated 1RM from any set, warm-up ramps built on the weight you are about to lift, and RPE or RIR turned into a percentage. The maths happens here, not on your phone’s calculator.
You keep the pace, it keeps the time
Work and rest run on their own. The exercise you are on, the one coming next and the round counter stay in view, and the cues work without looking at the screen.
See exactly how it is done
Every exercise in the catalogue comes with an animated demonstration of the movement, the equipment it calls for and your own history on it.
Every workout leaves a mark
A calendar of what you actually did, and how the numbers moved week after week. Consistency is easier to hold on to when you can see it.
Build your own
Choose exercises, sets, reps and rest and save the result, or design a timed circuit round by round. You shape it around the time you have, not the other way round.
Terms and privacy
The conditions of use and the handling of personal data for this app.
Before you start
KAI Fitness is a training tool, not a medical device, and it does not give medical advice. If you have a health condition, an injury or you are returning after a long break, check with a doctor before starting a new programme. For questions or problems with the app, write to the address below.