The app you already use
phase.fitness for Intervals.icu users
Intervals.icu already holds your fitness, fatigue and zones. What it does not write is the block. phase.fitness plans the phases, pushes each session to your Intervals.icu calendar with the structure intact, and reads the load back.
Updated
The short answer
phase.fitness connects to Intervals.icu two-way for endurance: planned cardio sessions are pushed to your calendar as structured workouts with intervals and heart-rate or power zones, and from Intervals.icu they reach Apple Watch, Suunto, COROS, Garmin and the rest. Completed sessions come back with the full metrics, along with HRV, resting heart rate and CTL/ATL, which is also how Apple Health data reaches phase.fitness. Strength sessions are counted in your Intervals.icu load but not written there — they go to Hevy, Liftosaur or a Garmin watch. When a phase ends, the AI reads the sessions and the load and writes the next block.
How do I get structured workouts into Intervals.icu automatically?
Let phase.fitness write them: every planned cardio session is pushed to your Intervals.icu calendar as a structured workout with intervals and heart-rate or power zones intact, and from there it reaches the devices Intervals.icu supports. Completed sessions come back with full metrics, HRV and load, and the next block is written from them.
Does strength training count in Intervals.icu load?
It does with phase.fitness: gym sessions go to Hevy, Liftosaur or a Garmin watch, and they are counted in your Intervals.icu load, so the fatigue they cause sits next to the rides and the runs. Intervals.icu does not receive the strength sessions themselves, and the calisthenics runs in the phase.fitness player.
Your week, honestly
The calendar is empty until you fill it.
Intervals.icu shows fitness and fatigue beautifully; the sessions that move them are typed in by hand or copied from a plan that does not know your numbers.
The plan does not know the load.
CTL, ATL and ramp rate are right there, and the plan for next month was written without them.
Strength is invisible to endurance apps.
The gym happens, adds fatigue, and never shows up in the picture.
What phase.fitness does about it
Structured workouts on your calendar
Every planned cardio session is written to Intervals.icu with intervals and zones intact, and from there to the watch you use.
Load comes back
Completed sessions return with the full metrics, plus HRV, resting heart rate, CTL/ATL and ramp rate — and it is the route for Apple Health data too.
Strength counted in the load
Gym sessions go to Hevy, Liftosaur or a Garmin watch and are counted in your Intervals.icu load, so the fatigue picture includes them.
Blocks from the endurance documents
Base, build, peak and taper on a polarized distribution, with the volume ramp set by your level and the next block read from what came back.
Programs to start from
Each of these is a page of its own, with the phases, a sample week and the evidence behind it.
CSCycling training plan built on power zones and real strength12–20 wk · 5–6 d/wk · all levels
CSHalf marathon training plan that keeps you strong10–14 wk · 4–6 d/wk · all levels
CSTriathlon training plan: three sports and one strength day12–20 wk · 6 d/wk · intermediate
CSRowing training program: erg, base and strength10–18 wk · 5–6 d/wk · all levelsThe apps you already use
Intervals.icu receives cardio and counts strength; it does not receive strength sessions themselves, and calisthenics runs in the phase.fitness player.
The evidence
Read more in the knowledge base
Frequently asked questions
Does phase.fitness push workouts to Intervals.icu?
Yes. Planned cardio sessions are written to your Intervals.icu calendar as structured workouts with intervals and zones, and completed ones come back with the full metrics.
Can I use Apple Watch?
Through Intervals.icu, yes: the planned session reaches the watch from your Intervals.icu calendar, and Apple Health data reaches phase.fitness the same way.
Does phase.fitness read my CTL and ATL?
Yes. Fitness, fatigue and ramp rate come into phase.fitness with the sessions, along with HRV and resting heart rate, and are part of what the AI reads when a phase ends.
The only app that plans strength, cardio and calisthenics together
For an endurance athlete on Intervals.icu the calisthenics day is the trunk and scapular strength the sport erodes — holds and hanging work — run in the phase.fitness player and counted in the same phase.
Right now, phase.fitness is the only training app that writes strength, cardio and calisthenics into one periodized program — same calendar, same phases, same recovery budget.
You choose the mix. A calisthenics-only plan, a cardio-only block, strength plus cardio, or all three: the phases, the end-of-phase analysis and the sync work the same way with one modality or three.
Why calisthenics is in the plan
Bodyweight skill work is strength training in a different shape. Straight-arm work, levers and handstands build scapular control, tendon capacity and relative strength that barbell and machine work leave untouched, and they transfer because they are closed-chain, whole-body patterns. Treated as a modality rather than a warm-up, they get sets, holds and progressions like a squat does.
No exercise catalogue on the market contains a tuck front lever, so those sessions run in the phase.fitness built-in player; strength goes to Hevy, Liftosaur or a Garmin watch, cardio to Garmin and Intervals.icu. How the skill work is programmed.
Free to start, no card. Connect the apps you already use and build the first phase.