Sterka — the strength coach you don’t have to second-guess · the long version

The engine does the math. The coach does the talking.

The front page makes the claims. This page is where they cash out — the whole machine, in seven chapters.

01 · The split

One brain, two jobs.

Sterka is a deterministic workout engine voiced by a coach — not a model writing workouts. The parts don't blur.

The engine Writes every session and every number. Same history in, same session out — deterministic, and tested to stay that way.

The coach AI, and it says so. Speaks the engine's numbers in sentences and drafts changes. The numbers are the engine's — never its own.

You Decide and lift. Today's session is already on your plan. The coach never edits it uninvited — you ask, it drafts, you approve.

02 · The screening

It starts with questions, not weights.

Before the first prescription, Sterka asks — because handing a stranger working weights without asking is how people get hurt.

Readiness A screening in the PAR-Q+ shape — the physical-activity readiness questionnaire a good trainer runs before session one. Flags route you to a clinician before a program starts — not after something tweaks. Some of those answers also keep near-max work off your plan: the wave's peak drops out of the rep-out below and comes back as a single at back-off weight.

Goal Get Stronger or Build Muscle. One choice; it steers every set that follows.

Your gym The equipment you actually have decides the exercise pool. No prescriptions for a machine you don't own.

Constraints A cranky shoulder, a movement to avoid — logged as constraints the engine must respect, with an expiry so old injuries don't haunt the plan.

Sterka prescribes resistance training, not medicine.

03 · The arithmetic

One hard set becomes a four-week wave.

Everything anchors on a set you actually did. Here is the whole chain, worked on one bench set — no step hidden. The wave alternates two four-week blocks: fives first, the builder; then the test block, worked here in full.

Your set 62.5 KG × 5 — your last hard set of bench

Estimated 1RM 62.5 × 36 ÷ (37 − 5) = 70.3 KG — Brzycki; reps past ten don't raise the estimate

Training max × 0.90, rounded down to the nearest 2.5 → 62.5 KG — seeded low on purpose: the first block is the assessment, and the test single stays clean when its block arrives. Landing back on your set's weight here is rounding coincidence, not the rule.

Block one · The builder — new lifters start here

The fives Four weeks at 45.0–50.0 · 72–80% TM, climbing by effort — RIR 3, then 2. Week 3: 55.0 × 3+ — an AMRAP (as many clean reps as you have) at 88%. Not the real test. It is held back too — by your health screen or injury notes, or by a gym that can't fail the lift — but not by the twelve-week floor below, which reaches the heavy single only.

Block two · The test — worked in full

Week 1 · Triples 50.0 × 3 → 52.5 × 3 → 55.0 × 3 · three climbing sets of three · 80–88% TM · RIR 2 (reps in reserve — stop that many clean reps short of failure)

Week 2 · Doubles 50.0 × 2 → 55.0 × 2 → 57.5 × 2 · sets of two, heavier · 82–92% TM · RIR 1 — 82% asks for 51.25, and the bar takes 50.0

Week 3 · The test 60.0 × 1+ · one clean rep, then every clean rep you honestly have · then two lighter sets of 45.0 × 5 · RIR 3

The held-back cases The rep-out isn't universal. It is held where a lift needs safety bars and the gym has none, where a squat, deadlift or other spine-loaded lift is inside your first twelve logged strength weeks, where anything on your health screen or injury notes makes a near-max set the wrong call, and on any day the engine is already easing this lift back — coming off a layoff or an illness, say. — what arrives instead depends on why. A press the gym can't fail safely runs a variant it can; a squat ships the same weight with the test taken off; a health or injury hold usually brings the weight down too, into the back-off band, unless the note names an area we can't map to particular muscles — that holds the test everywhere and leaves the weights alone. The card names the kind of reason, never a diagnosis.

What still moves the max Two of those can. Your gym and your first twelve weeks are about your setup and your history, so finish the block's heaviest prescribed set cleanly, rate it, and the number climbs half a step — provided nothing on your health screen or injury notes is holding the lift too, which outranks both. — every other reason on that list holds the number where it is, and where the engine eased the lift that block isn't read as a decline either. Telling your gym profile you do have safety bars brings the test back on that lift. On the health side it returns when the screen or the note no longer applies — update your screening or talk to your clinician first.

Week 4 · Deload top 37.5 · 60% TM · working volume halved

The loop What the test single delivers writes the next wave's training max: beat it by enough and the max climbs — never past what the single itself proves — hit it and it holds, miss it and the next wave backs off 10%. Recalibration off the bar, not a survey — only the single moves the max; a fives block holds it. The single is your progress, on record.

This chapter worked the Get Stronger spine. Build Muscle runs the same chain with a different one — the same rigor, different lever: loads key off the estimate itself at 65–77%, and the wave climbs by sets — 3 × 10, then 4, then 5 — because for muscle, sets carry the overload.

Run your own set on the front page — the calculator there runs block one, live.

Or see all four weeks at once — the wave loading planner lays out the whole block from one set.

04 · The session

The phone lies on the bench and asks for nothing.

Lift Mode is built for a phone on a bench: the prescription is the hero, logging is one tap, and the screen never asks for anything mid-set. Four moments from the test block's week 3 — the test day:

01 · The ladder is already built 45.0 KG × 3 Warm-up · rung 3 of 5 · 30 → 35 → 45 → 50 → 55

Five rungs to a heavy single, each one a tap. You never do ladder math at the rack again.

02 · The heavy set leads the day 60.0 KG × 1+ RIR 1 · 95% TM — 59.375 on paper, 60.0 on the bar · per side: one 20 plate

The test single, with the stop rule on screen: every clean rep, one left in reserve. The reps you deliver write the next wave's max. Where the rep-out is held back — a lift the gym can't fail safely, a squat, deadlift or other spine-loaded lift inside your first twelve logged strength weeks, something on your health screen or injury notes, or a lift the engine is already easing — this day is a different set: a variant, the same weight without the test, or a lighter one. Your gym and your first twelve weeks still move the max on a set you rated, as long as nothing on your health screen or injury notes is holding the lift too; every other reason holds it where it is.

03 · Rest is prescribed, not suggested 4:00 Next · 45.0 KG × 5 · RIR 3 · bar + 10 + 2.5 per side

Four minutes after a heavy strength set. The timer runs, and the next set — load, reps, plates per side — is already on screen.

04 · Every load has a reason on record Why this weight? One tap under any set

Week 3 of 4 — the wave peaks. The 1+ rep-out: 95% of a training max seeded at 90% — or, where it's held back, whatever the day became instead and the kind of reason it was. The fives after: volume banked at 70%. Every load then rounded to what plates can make. Next week: deload. Sentences, not a black box.

05 · The adjustments

Programs don't watch you train. This one reads the log.

Some of what changes is planned; the rest is life interfering — and the difference between a plan and a coach is what happens then. The engine reads every logged set, and the calendar gaps between them.

Deload, planned Week 4: working volume halves, the top set drops to 60%. Narrated before it happens — this is the plan working, not the plan going soft.

Two weeks off Once a gap runs past your own usual cadence, caps ease you back. Up to about three weeks that's 85% of your estimated max on the first session, 92% on the second. Miss one session and nothing happens. Go quiet and the engine ramps you back; it doesn't hand you last month's loads and hope.

A month away Past three weeks, the first session back is deload-shaped: loads capped at 70% of your estimated max, half the volume. Then 78% and 84% before the cap releases and the wave resumes where it left off — no restart from zero, no pretending nothing happened.

Stalled, strength Miss the week-3 single and the next wave's training max backs off 10%. Backing up is how the bar starts moving again — announced, not slipped in.

Stalled, muscle Same load, same reps, three sessions running — each one closer to failure. That reads as a plateau, and the prescription is a deload, not more grinding.

Not recovered Chest ~41% recovered, so heavy pressing waits a day. Recovery is tracked per muscle, fed by the sets you log — harder and heavier sets cost more, each muscle recovers on its own clock, and a body isn't one number: Sterka won't pretend it is .

Rep-out day 62.5 × 11 logged. Reps past ten don't raise the estimate — one big rep-out shouldn't reset your whole load table, and the cap makes sure it can't .

06 · The coach

The coach proposes. You decide.

The coach is the engine's voice — same brain, same numbers, in sentences. It briefs you on training days, answers "why" in plain terms, and drafts changes you can apply or ignore.

§1 It doesn't get to invent a number. Every load it mentions comes from the engine's tables — when it proposes a change, the engine has already run the math.

§2 It changes nothing until you apply it. The generated session is already yours; the coach's proposals arrive as drafts. Your plan changes when you say so, not when a model decides to.

§3 It reads your life only to change your training. A cranky shoulder, ten days off the log, a movement you'd rather avoid — inputs to the prescription, never a wellness lecture.

§4 It knows where coaching ends. No medical calls, no supplement plans, no diet talk. It says so and points you to the right person.

You

shoulder pinched on the last warm-up single

Coach

Noted, and logged against today. I’d pull the test single — no near-max through a fresh pinch — and bank the volume instead: fives on a neutral-grip press, same pattern, less rotation through the shoulder, and the wave retests the single next week. If it pinches again, have it looked at.

Proposal · Today's test single removed · fives moved to a neutral-grip press Status · Waiting on you — nothing changes until you accept

07 · The refusals

What Sterka won't do.

Half of coaching is what a good coach refuses to do. Same here.

Won't No readiness score. One number for a whole body is theater. Recovery is tracked per muscle, and shown that way.

Won't No confetti, no leaderboards. A PR gets its number and one flash of color. Training isn't a slot machine.

Won't No feed, no followers. The only audience is the bar.

Won't No selling your data. Your training data is never used or sold for advertising. It writes your training; that's its whole job.

Won't No black box. Every load traces back to arithmetic, one tap deep. If the engine can't explain a decision, it doesn't make it.

Won't No everything-app ambitions. Strength training at launch, depth before breadth.