No black box. Here are the rules behind every target, so you can check the engine against your own training logic.
Every target weight comes from a fixed rule, not a model that guesses. The same history and the same settings always produce the same prescription. Each change carries a plain-language reason, and you can open it from any exercise.
Hit every target rep and the next session adds a small step. Miss and you repeat the weight. Three misses in a row trigger a deload.
Work inside a rep range. Add reps until every set reaches the top of the range, then add weight and drop back to the bottom. A big rep surplus on a last set can skip ahead a step.
Heavy low-rep work, moderate work and high-rep work progress on separate tracks. A miss moves a lift to a different set and rep scheme before the weight goes up again.
Heavy, medium and light days rotate, and each intensity progresses on its own rep range.
Anneal estimates your max from each working set using standard formulas (Epley, averaged with Brzycki for sets of 2 to 10 reps). Warm-ups are excluded. When you record how many reps you had left, that is counted too. The trend weights recent sessions more heavily, with a half-life of 30 days, and it is marked low confidence when there is little recent data, which the chart shows as a dashed line.
Targets are rounded to weights you can actually load with your gym profile's bar, plates and dumbbells. Deloads and readiness cuts round down. If a rounding step would erase an intended increase, it carries to the next session and says so.
If an estimated max does not improve across three consecutive sessions of the same lift, with most of the planned volume completed, Anneal schedules one lighter session at 90% of the last working weight, then resumes a step below and builds again. Skipped sessions do not count as stalls, and deloads never stack. If a second stall comes within six weeks, Anneal suggests an easier scheme but never applies it for you.
Your daily readiness score compares HRV, sleep and resting heart rate from Apple Health with your own 30-day baselines, plus a quick check-in. A middling score can trim an accessory set. A low score can reduce accessory volume and, with Pro, reshape the day with a before and after. Readiness can only reduce a session, never add to it, and total load reduction is capped. A trimmed session that you complete still counts as a success for progression.
After 10 days or more away, Anneal restarts you below your last weights and ramps back up with a cap at your previous load, with no guilt copy. If you flag an injured area, Anneal stops prescribing movements that load it and keeps progressing everything else. You declare when it has cleared, and the affected lifts then ramp back conservatively. Anneal is not medical advice or rehab: see a professional for pain or injury.
Want the exact numbers? Read the full progression rules, with a worked example for each one.
Compare how this differs from other apps: Anneal vs Fitbod, vs Hevy, vs Strong · vs MacroFactor.
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