The back squat works the quads first, with the glutes, hamstrings and core doing the supporting work — that is exactly how the Zyra Workouts catalog files it, and that row decides the muscle map, the weekly volume count and the alternatives the app offers. Below: the muscles, a mechanical setup checklist, the rep and RIR targets by goal, how the load steps, and the plate math for a 100 kg bar.
Muscles worked
| Role | Muscle | Weekly-volume credit per working set |
|---|---|---|
| Primary | Quads | 1.0 set |
| Secondary | Glutes | 0.5 set |
| Secondary | Hamstrings | 0.5 set |
| Secondary | Core | 0.5 set |
The quads straighten the knee as you stand up out of the bottom; the glutes and hamstrings extend the hip at the same time; the core holds the trunk angle so the bar stays over the middle of the foot. The app credits every working set (anything that is not a warm-up) with one set for the primary muscle and half a set for each secondary — so three sets of squats add 3 sets to quads and 1.5 sets each to glutes, hamstrings and core in the weekly landmarks (quads 14, glutes 10, hamstrings 10, core 10 sets a week). The weekly sets calculator does that sum for a whole week.
Setup and execution
Mechanical cues only — the point is a repeatable rep, so every logged set means the same thing.
- Bar position. The bar sits across the upper back, either on the traps (high bar) or a little lower across the rear shoulders (low bar). Both are back squats in the catalog; log them under the same row unless you want separate histories.
- Stance. Roughly shoulder width, toes turned out slightly. Pick one stance and keep it — a stance change changes what a given weight × reps means.
- Brace and unrack. Big breath, ribs down, take the bar out with both feet under it, then two short steps back.
- Descent. Break at the hips and knees together; keep the bar over the middle of the foot; go as deep as you can while holding the trunk angle steady.
- Ascent. Drive the floor away, hips and shoulders rising at the same rate, and exhale near the top.
Count only full reps; the app has a separate partial-rep field (8+2 = eight full, two partial) if you want to record a short rep without inflating the count.
Rep and RIR targets by goal
The back squat is a compound exercise, so the generator gives it the compound table:
| Goal | Reps | RIR | Rep ceiling | Sets (beginner / intermediate / advanced) |
|---|---|---|---|---|
| Strength | 3–5 | 2 | 6 | 3 / 4 / 5 |
| Hypertrophy | 6–10 | 2 | 10 | 2 / 3 / 4 |
| General | 8–12 | 2 | 12 | 2 / 3 / 4 |
The rep ceiling is the number the app compares your last set against: the midpoint of the rep range plus the RIR target (round((min + max) / 2) + RIR). RIR is reps in reserve — how many more reps you could have done. These targets are the app's defaults, not a law; a program you build yourself can set anything. The default rest between sets for this row is 180 s, the longest in the catalog.
How progression steps on this exercise
A barbell exercise moves by one plate pair. In the default gym the smallest plate is 1.25 kg, so the step is 2 × 1.25 = 2.5 kg. The rule is the same for every exercise in the app:
Your last set vs the target (hypertrophy, 6–10 @RIR 2, ceiling 10) | Next recommendation |
|---|---|
100 kg × 11 (above the ceiling) | 102.5 kg × 6 — progress: add a step, reps reset to the floor |
100 kg × 10 (inside the range) | 100 kg × 10 — hold |
100 kg × 5 (under the floor) | 97.5 kg × 6 — back off one step |
In plain terms: beat the ceiling and the bar gets heavier and the reps start over at the bottom of the range; miss the floor and the bar gets lighter; anything in between, you repeat and try to add reps. This is arithmetic from the progression engine, not a trial result. The 1RM calculator turns any of those sets into an estimated one-rep max if you want to see the trend in one number, and the load chart shows what the percentages look like across the bar.
Loading the bar: plate math for 100 kg
The app describes a bar load as plates per side, times two, plus the bar. With the default inventory (20, 15, 10, 5, 2.5, 1.25 kg plates on a 20 kg bar) it picks the largest plates first:
| Target | Plates per side | The app's label |
|---|---|---|
60 kg | 20 | (1×20) × 2 + 20 kg bar = 60 kg |
80 kg | 20 + 10 | (1×20 + 1×10) × 2 + 20 kg bar = 80 kg |
100 kg | 20 + 20 | (2×20) × 2 + 20 kg bar = 100 kg |
102.5 kg | 20 + 20 + 1.25 | (2×20 + 1×1.25) × 2 + 20 kg bar = 102.5 kg |
120 kg | 20 + 20 + 10 | (2×20 + 1×10) × 2 + 20 kg bar = 120 kg |
Notice the 102.5 kg row: one progression step from 100 kg needs the 1.25 kg plates. If your gym profile has no 1.25 kg plates, the step becomes 5 kg (two 2.5 kg plates) and the wand tells you when a recommended load cannot be built from your inventory. The plate calculator runs the same decomposition for any weight, in kg or lb.
Alternatives
The app's swap list for the back squat keeps the primary muscle (quads) and ranks by feasibility in your gym, then same category, then same equipment:
| Alternative | Why it ranks where it does |
|---|---|
| Front squat | Same muscle, same category (compound), same equipment (barbell) — the top score |
| Bulgarian split squat | Compound, but dumbbell — one point lower |
| Hack squat | Compound, machine |
| Leg press | Compound, machine; ties with the hack squat and sorts by name |
| Walking lunge | Compound, dumbbell |
| Leg extension | Same muscle but an isolation exercise — last |
The short version
Quads primary; glutes, hamstrings, core secondary. Compound targets: 3–5, 6–10 or 8–12 reps at RIR 2 depending on the goal, 180 s rest. The bar moves 2.5 kg at a time when you clear the ceiling. 100 kg is two red plates a side. Educational overview only — training guidance, not medical advice.