How a program gets planned in phases

Your body adapts to a stimulus and then stops adapting to it. Periodization is the answer to that: change what the training is asking for, on a schedule, so the stimulus keeps being new enough to matter and old enough to accumulate.

The vocabulary is simpler than it looks:

• Microcycle — a week. The unit you actually live in.
• Mesocycle — a block, usually three to five weeks with a lighter week at the end. This is what Phase calls a phase.
• Macrocycle — the whole run at a goal, typically three blocks or more.

Because that is roughly how long it takes for a change in training to show up as a change in performance, and roughly how long you can push a single quality before accumulated fatigue starts hiding the progress underneath it.

Shorter than that and you are changing the plan before it has said anything. Longer, and you spend the last weeks confirming what you already knew.

This is also the reason the subscription is quarterly rather than monthly: one month is one block, and one block is the part you could have written yourself. The pricing page says the same thing at more length.

Linear periodization moves in one direction: volume down, intensity up, across the block. It is the classic novice progression and it works for a long time.

Undulating periodization varies intensity within the week — a heavy day, a moderate day, a volume day. It suits people who need several qualities at once, which is most people who lift and also do something else.

Block periodization concentrates on one quality per phase while the others hold. It is what most hybrid athletes end up doing whether they call it that or not.

Phase does not pick a doctrine and impose it. The structure follows your goal, your available days and your equipment, and the phases are laid out on a real calendar so you can see what the model actually chose.

The AI is used at two moments, and only two:

• Writing a phase. Turning a goal, a number of days, an equipment list and a set of injuries or exclusions into a sequence of sessions with exercises, sets, loads and progressions.
• Reading a phase that ended. Comparing what was planned to what you did, and using the gap to shape the next block — more of what worked, less of what got skipped, adjusted loads where the numbers moved.

That second one is the part worth paying for. The first is a good template generator; plenty of things can do it. The second requires knowing what happened, which requires the completed sessions coming back from the app or watch you trained with.

• It does not invent a session every morning. Your week is planned in advance, because a plan you cannot see is not a plan.
• It does not touch calisthenics programming. Bodyweight skills follow a deterministic progression from a curated catalogue — no model in the loop, and no credits spent.
• It does not diagnose anything, and it is not a substitute for a doctor or a physiotherapist. Injuries you declare are constraints it works around, not conditions it treats.