Your Training App Counts Sets Wrong. 67 Studies Prove It.

Open your training app after a push day. Count the sets. Four bench press, three overhead press, three tricep extensions. The screen says ten.

Now recount.

Those four bench press sets trained your chest directly — but they also worked your triceps and front delts as secondary muscles. The overhead presses hit shoulders directly while triceps helped push the weight. Only the tricep extensions were pure isolation.

When a team of researchers from Florida Atlantic University recounted sets this way across 67 studies and 2,058 participants, giving indirect muscle work half the credit of direct work, something shifted.

Your ten logged exercises became 17 muscle-specific fractional sets spread across three muscles — and this fractional counting method outperformed every other approach to measuring training volume.

Not by a slim margin. The evidence ranged from strong to very strong across every combination of outcomes the researchers tested — muscle size, strength, both together. The traditional method, where every set counts as one regardless of which muscles did the heavy lifting, lost.

The direct-only method, which ignores secondary muscle work entirely, also lost. Fractional counting won every round.

The Ruler Was Wrong

This is where the finding turns personal. You track your five-day split religiously. You ask the same question every lifter asks: am I doing enough sets per week, or too many?

The internet gives you a number somewhere between ten and twenty. You adjust, add a set here, drop one there, and trust the total your app displays.

But every answer you’ve ever received used a counting method this meta-analysis found inferior. The number might have been fine — the unit of measurement was broken.

Think of it like an odometer that doesn’t know whether you’re on a highway or a dirt road — the miles tick up the same way either direction, but the wear on your car is completely different.

Your training app records sets without distinguishing between a barbell row that hammers your lats directly and the bicep work happening silently alongside it. Pelland’s team proved that distinction matters — and that treating indirect muscle work as half a set captures what’s actually happening better than any alternative.

The practical implication hits immediately. A program prescribing sixteen sets for back that includes rows, pull-ups, and deadlifts isn’t delivering sixteen sets of back stimulation. It’s delivering sixteen direct sets plus a cascade of fractional sets flowing into biceps, rear delts, and forearms. The real volume picture is bigger than the screen shows — and for some muscles, dramatically so.

The Pay Rate Drops After Ten

Once the counting method is corrected, the next question lands: how many fractional sets per muscle actually matter?

The researchers mapped the dose-response curve for muscle growth with a level of precision nobody had published before. They broke the relationship into efficiency tiers — not vague ranges, but specific thresholds where each additional set costs more recovery for less return.

The first four sets per muscle per week cleared the minimum effective dose. That’s where detectable growth begins. From sets five through ten, each additional increment of growth required roughly six more weekly sets — the sweet spot. This is where the investment pays full wages.

Then the rate changes.

Between eleven and eighteen weekly sets, the same unit of growth required about eight and a half additional sets. The work increased. The return held, but the price climbed.

Between nineteen and twenty-nine sets, each growth increment cost nearly eleven additional sets. And beyond thirty? About twelve and a half sets per detectable change.

The curve never hits zero — more sets still produced more growth across the full range the data could measure, with a hundred percent probability that the relationship was positive. But the efficiency dropped with every tier.

Sets one through ten earned full hourly rates, and sets eleven through eighteen earned about seventy percent. By sets nineteen and beyond, each set worked harder for roughly half the payoff of the early ones.

Where Your Program Actually Sits

This is where the breathing room arrives. Your twenty-set program isn’t a waste. The first ten sets are doing the heavy lifting — full-wage growth.

Sets eleven through twenty sit in the diminishing-returns zone, still contributing but at a declining rate. You’re not overtraining — you’re paying overtime you didn’t budget for.

The shift isn’t about doing less. It’s about seeing what each set is actually earning. A reader who assumed every set contributed equally now sees a curve — steep at the start, flattening through the middle, grinding by the end.

The recovery cost of set twenty is the same as set one, but the growth return is not. That asymmetry is the tax nobody mentioned.

For anyone adding cardio on top of that volume, the tax question doubles: does aerobic work cost additional muscle? Forty-three studies measured that trade-off across 1,090 people and found the effect on muscle growth was one hundredth of a standard deviation. The cardio sessions are not undoing the volume work.

And the honest part: this curve came from studies averaging about ten weeks. Whether the shape holds over six months or a year is something the data can’t fully answer yet. The researchers acknowledged that model uncertainty grows at higher volumes — the further out on the curve, the wider the range of plausible outcomes. The efficiency tiers are the best map available, not a GPS coordinate.

Four Sets of Strength. The Rest Is Something Else.

Here is where the study delivered its sharpest surprise.

For muscle growth, the curve diminishes but keeps climbing. For strength, it doesn’t just diminish — it flatlines.

The smallest detectable strength gain appeared at just one fractional weekly set. By roughly four sets, the researchers found a functional plateau. Additional volume beyond that produced no consistently measurable strength improvement.

Four sets.

Your sixteen-set leg day suddenly splits in half. Sets one through four are building strength and size simultaneously. Sets five through sixteen? Those are building muscle tissue — which is a perfectly valid goal — but they’re not making the barbell feel lighter.

You’ve been doing four sets of strength training and twelve sets of bodybuilding without your program knowing the difference.

The divergence between strength and size was one of the clearest findings in the entire analysis. The strength curve flattened dramatically earlier, with what the researchers described as considerably more pronounced diminishing returns than hypertrophy.

Where the muscle-growth curve kept rising — slowly, expensively, but rising — the strength curve essentially gave up responding to additional volume.

This isn’t a reason to train less. It’s a reason to understand what each set is actually doing. A lifter who wants to get stronger needs a handful of focused sets. A lifter who wants to get bigger needs more.

A lifter who wants both — which is most people — is running two different programs simultaneously, whether the training app recognizes it or not.

The Honest Part About Half-Sets

The fractional coefficient — counting indirect sets at fifty percent of direct — is an approximation. The researchers were transparent about this.

A lat pulldown probably stimulates biceps at something other than exactly half. A close-grip bench press likely hits triceps at more than half. The 0.5 value is what fit the data best across 67 studies, not a biological constant measured in any individual exercise.

This makes the finding more credible, not less. The fractional method captures the directional truth — indirect sets contribute meaningfully but not equally — without pretending to know the exact ratio for every movement.

And for the question you actually care about — am I in the right volume range? — the precision of 0.5 versus 0.4 versus 0.6 matters far less than the fundamental insight that indirect work counts at all. Your app currently scores it at zero or one. The evidence says the real answer is somewhere in the middle, and half is the best single estimate across the available data.

A Decade of Arguing About the Wrong Thing

One finding from this meta-analysis deserves its own moment, because it settles one of the longest-running debates in fitness.

Bro split or push-pull-legs? Train each muscle once a week with maximum volume, or spread the sets across three shorter sessions? Fitness influencers have built entire platforms arguing one side.

Reddit threads run hundreds of comments deep. The debate has shaped millions of training schedules.

The evidence says it barely matters for muscle growth.

When Pelland’s team analyzed 35 studies with 1,032 participants, the effect of training frequency on hypertrophy landed at a marginal increase of just 0.32 percent per additional weekly session — with the range of plausible values crossing zero.

The probability that frequency has any positive effect at all was 91.3 percent, which sounds high until you realize that range included the possibility of no effect whatsoever.

The bro-split camp and the PPL camp spent a decade arguing about the seat arrangement on a plane that lands at the same destination. Frequency changes the schedule on your phone — not the muscle on your frame. When total weekly volume is matched, how you distribute it across the week is a logistics decision, not a biological one.

For muscle size, at least. Strength told a different story.

Why Powerlifters Squat Three Times a Week

Higher training frequency did show a clear positive relationship with strength gains — every additional weekly session was associated with a 3.27 percent increase in strength, with a hundred percent probability the relationship was real.

But the researchers proposed an explanation that reframes the entire finding. The strength benefit of higher frequency likely comes from more frequent practice of the movement pattern — not from additional muscle stimulus.

Squatting three times per week makes you better at squatting the same way that practicing piano three times per week makes you better at piano. The skill improves. The underlying tissue doesn’t need the extra sessions.

This is why powerlifters train the same lifts multiple times per week while bodybuilders often don’t. The powerlifter is rehearsing a skill. The bodybuilder is stimulating tissue. Both are correct — they’re just doing different things, and frequency serves one goal while volume serves the other.

An earlier meta-analysis pooling 15 studies had already shown the same pattern — more volume, more growth — but counted total sets without distinguishing direct from indirect work. Pelland’s team evolved that baseline. The direction held. The counting got sharper. [1]

The Software Update

Your training app still works. The exercises are still good. The consistency still matters more than any single variable.

But you read the screen differently now. The twenty sets your app shows for back are really twenty-plus fractional sets once you count the bicep and rear-delt spillover from rows and pull-ups.

Your first ten sets per muscle earn full returns. The next ten are working at a declining rate — still valuable, still contributing, but with less bang for each additional rep. Strength stops responding to volume somewhere around four sets. Everything after that is building size.

The firmware updated. Same hardware. Better operating system.

Your training schedule — whether you hit back once a week or three times — is your choice to make based on your calendar, your recovery, and your preferences. The science says it won’t change the muscle on your frame either way, as long as the weekly total stays the same. One less argument to lose sleep over.

And the next time someone in your gym group chat asks how many sets per week they need, you have a better question to send back first: how are you counting?