How much is enough
Almost every programme tells you how many sets to do today. Very few tell you how many your chest got this week, which is the number that decides whether it grows.
The three numbers
The least work that still moves the needle. Below it you are maintaining at best — the sessions happen, the muscle stays where it is. This is the number worth caring about most, because almost everyone who is stuck is stuck under it on something.
The upper edge of the productive window. Between MEV and MAV is where most growth actually accrues, and where a sane programme spends its time. It is a band, not a bullseye.
The ceiling. Past it the sets still happen, the fatigue still accumulates, and the adaptation does not follow — you are paying for work you cannot recover from. Going over occasionally is a training decision. Living over it is a slow injury.
The unit: weighted sets per week
Not sessions, not exercises, not hours. Sets, counted per muscle, across the whole week. Three chest sets on Monday and three on Thursday is six, and six is the number that matters.
Weightedis the part that usually gets skipped. A barbell row is not one set of “back”. It is a full set for your lats, most of a set for your upper back, a real share for your biceps, and a smaller one for your rear delts and forearms. Count it as one set of back and you will under-count your arms every week of your life, then wonder why they never catch up.
Heatwayve apportions every logged set across the muscles that did the work, using a per-exercise contribution table — and then holds the weekly total against the landmarks below. The same numbers drive both. You can read the exact split for any movement in the exercise library.
Weekly, but not all at once
The dose is weekly. How you spread it still matters, just less than people think. The meta-analytic answer is that major muscle groups respond best trained at least twice a week — and that whether three beats two is, on the current evidence, undetermined.
Which is the useful version of the finding: hit your weekly number across two or more sessions and the frequency question is answered. Twelve sets of chest in one heroic Monday is not the same twelve. The three-day A/B/C rotation exists for this reason — each muscle comes around more than once, without anyone having to plan it.
The landmarks, per muscle
Weighted sets per week. These are the exact values Heatwayve audits against — this table is generated from them, so it cannot drift.
| Muscle | MEV | MAV | MRV |
|---|---|---|---|
| Quads | 8 | 18 | 22 |
| Hamstrings | 6 | 12 | 16 |
| Glutes | 4 | 12 | 16 |
| Calves | 6 | 12 | 16 |
| Chest | 8 | 16 | 20 |
| Lats | 6 | 14 | 22 |
| Upper Back | 6 | 16 | 22 |
| Traps | 0 | 12 | 20 |
| Erectors | 0 | 6 | 12 |
| Front Delts | 6 | 12 | 16 |
| Side Delts | 6 | 12 | 16 |
| Rear Delts | 6 | 12 | 16 |
| Biceps | 5 | 14 | 20 |
| Triceps | 6 | 14 | 18 |
| Core | 0 | 16 | 25 |
Two entries deserve a note. Traps and Core carry an MEV of zero — not because they do not matter, but because deadlifts, rows and carries already deliver plenty indirectly. Their ceiling is the useful half. Erectors are the same idea, sharper: that row is a fatigue budget, there to warn you when a deadlift-heavy stretch is quietly stacking axial load.
Each deltoid head is judged on its own. Lumping them together is how side delts end up permanently under-trained behind a pile of pressing.
What these numbers are not
They are not a measurement of you. Volume tolerance moves with training age, sleep, stress, how much food you are eating and what else is in the week. Two people with identical numbers can sit fifty per cent apart on what they can actually recover from.
Treat them as a well-reasoned starting point and let your own evidence correct them. A band you sit inside comfortably and keep progressing on is right for you, whatever the table says. The honest use of a landmark is to notice you are nowhere near one.
Where this comes from
Establishes the graded relationship between weekly sets and hypertrophy, with meaningful growth clustering from roughly ten sets per muscle per week.
Weekly volume is the dose, but it is better split than stacked: major muscle groups respond best trained at least twice a week. Whether three beats two is, on this evidence, undetermined.
Israetel M, Hoffmann J, Smith CW. Scientific Principles of Hypertrophy Training. Renaissance Periodization, 2021.
The MEV/MAV/MRV vocabulary and the per-muscle starting landmarks. Practitioner-derived, not a controlled trial — treated here as a well-reasoned starting point, not a measurement.
Heatwayve does this arithmetic for you every week, per muscle, from the sets you actually logged. Open the app.