Junk Volume: Why Half Your Sets Might Be Wasted (And How to Tell)

Junk volume is any set stopped too far from failure, or too fatiguing to recover from, to add meaningful muscle stimulus. If your sets end 5 or 6 reps shy of failure, you are paying the time, joint wear and recovery cost of training without collecting the growth. You will see the claim that about half of self-directed sets land here (survey data cited by Jeff Nippard). Treat that as an attention-grabbing estimate rather than a measured fact: it is not a peer-reviewed finding, and nobody has audited a representative sample of real gym sets against true failure. The defensible version is duller and still worth your time: some of your sets are costing you fatigue without contributing anything, and you almost certainly cannot name which ones, because we are bad at judging our own effort.

Junk volume meaning, in one line: sets that cost recovery but do not build muscle, usually because they stopped with 5+ reps in reserve. "Junk sets" is the same idea, counted one set at a time.

Plenty of lifters train 4 days a week, never miss a session, and barely grow. Almost always the problem is not their split or their protein. It is that their "hard" sets are not hard. They count the sets. The sets do not count back.

Below: what junk volume actually is, a 3-question test to spot it in your own sets, why the last reps of a set are thought to carry most of the stimulus, and how to fix it without just doing more.

What is junk volume?

Junk volume is training volume that costs you time, energy and recovery capacity without producing a proportional gain in muscle or strength. It comes in 2 kinds. The first, and more common, is sets stopped too far from failure to recruit and fatigue the muscle. The second is excessive sets: piling on volume past the point where each added set still pays off.

Most people assume junk volume means doing too many sets. It usually means the opposite: doing easy sets. A 5-set workout can be almost entirely junk if every set ends at 5-plus reps in reserve. Quantity is not the issue. Intensity of effort is.

What are junk sets?

Junk sets are the individual sets that make up junk volume: a set is junk when it ends with roughly 4 or more reps still in the tank, when the load is so light that the muscle never reaches full recruitment, or when it is so brutal that it costs you the next session. Most lifters picture a junk set as a lazy one. In practice it usually feels like work. The burn arrives, the bar feels heavy, and the set still stops 5 reps short of anything the muscle would call a stimulus.

The 3-question test: how do you know if a set is junk volume?

A set is junk volume if you ended it with more than about 3 reps left in the tank, used a near-trivial load, or pushed so deep into fatigue that it wrecks your next session. The practical test: could you have done 4 or 5 more clean reps? If yes, that set probably delivered close to zero stimulating reps, even though it counted on your training log.

Here is the catch: you are a bad judge of this. Lifters systematically underestimate how many reps they have left, which is the same thing as overestimating how close to failure they are. They feel the burn, the bar feels heavy, and they rack it thinking "that was a 1 or 2 RIR set" when video would show a fast, controlled bar with reps to spare. The internal sensation of effort outruns the actual mechanical proximity to failure. The one thing that reliably changes as a set gets genuinely hard is rep speed: reps slow down as a muscle nears failure, whether or not you feel it. That is why the second question below is the one worth trusting most.

Here is the 3-question test for any set you are unsure about:

1. Could you have done 4 or more clean reps? If yes, it is a junk set. The stimulating reps never happened.
2. Did your rep speed visibly slow in the last 2 or 3 reps? If every rep moved at the same speed, you never entered the effective-rep zone. That is junk.
3. Was the set so deep that it wrecked the rest of the session? A set that costs you 2 later sets is junk in the other direction: too much, not too little.

Pass all 3 and the set counts toward your hard sets per muscle per week. Fail question 1 or 2 and it is time to look honestly at why your RIR estimate is probably off, with the size of the error scoped properly: calling a set "2 RIR" when it is really a 4 or 5 is what was measured in trainees with under 6 months of experience, while trained lifters are typically off by more like 1 to 2 reps. Everybody's error grows the further from failure the call is made.

Junk volume vs effective reps

To understand why easy sets are junk, you have to understand effective reps, sometimes called stimulating reps. Before the numbers, the single most important caveat in this article: "effective reps" is a heuristic model, not a directly tested mechanism. It is an inference stacked on motor-unit recruitment physiology plus the proximity-to-failure training studies. Nobody has run the study where everything else is held constant and the only thing varied is the number of effective reps, measured directly rather than inferred from rep count and RIR. It is often presented as a finding. It is not one. It is a useful way to think about why the last reps feel different, and it should be weighed as that.

With that on the table: not every rep in a set is assumed to grow muscle equally. Chris Beardsley's stimulating-reps model estimates only about 5 stimulating reps per set taken to failure (likely toward the low end of a 5-8 range). That is an estimate from the model, not a measurement. Those are the final reps where full motor unit recruitment and a slow bar are thought to coincide.

Both conditions matter, and this is the part most articles botch. Full motor unit recruitment kicks in around 80-88% of 1RM, roughly a 5RM load, or, at lighter loads, only once you have fatigued into the back half of a set. But recruitment alone does not grow muscle. The fiber also has to shorten slowly. By the force-velocity relationship, a slow rep produces high mechanical tension per fiber; a fast, explosive rep recruits everything but produces low single-fiber tension because it is moving too quickly. That is why a snappy speed-bench rep does not build the same muscle as a grinding final rep, and why leaving 6 reps in the tank is biomechanically junk, not just psychologically lazy. The high-tension reps simply never happen.

So effective reps and the volume debate are not in conflict. On this model they are the same coin. A "hard set" counts as one unit of productive volume because it is assumed to deliver a handful of stimulating reps; an easy set delivers near zero. That is junk volume in one sentence: you pay the set cost without collecting the stimulating reps. Keep holding the model loosely, though. What the training studies actually support is narrower and less dramatic: hypertrophy increases as sets are terminated closer to failure, the effects are modest, and more failure is not monotonically better.

This reframes the whole "high volume vs low volume" argument. 3 sets to failure (~28 total reps) and 4 sets of 7 near failure (~28 reps) can grow similar muscle because the stimulating-rep totals end up comparable. The trap is doing 4 easy sets that never reach the stimulating zone: full volume cost, almost no benefit.

Is more volume always better? (the diminishing returns curve)

No. More volume helps, up to a point, then flattens, then turns negative. The landmark dose-response meta-analysis from Schoenfeld, Ogborn & Krieger (2017) found a graded relationship: each added weekly set per muscle bumped effect size by ~0.023 (about 0.37% extra muscle per set), and 10+ weekly sets beat 5-9, which beat fewer than 5. Volume matters. But notice the magnitude: that is a small, diminishing return per set, not a linear ramp you can ride forever.

The clearest picture of where the curve flattens comes from proximity-to-failure data. The Refalo et al. (2023) meta-analysis of 15 studies found only a trivial advantage for training to set failure versus not (ES = 0.19, CI 0.00 to 0.37, p = 0.045; note the interval touches zero), and no significant advantage for momentary failure specifically (ES = 0.12, CI −0.13 to 0.37, p = 0.343). The authors also raise the possibility that the relationship is non-linear rather than "closer is always better." Translation: you do not have to hit failure, and the honest size of the effect is small. But the same review's velocity-loss analysis shows you do have to get close:

Look at where the jump is. Going from "easy" to "moderately hard" nearly doubles the effect (0.20 to 0.39). Grinding from moderately hard all the way to absolute failure barely moves it (0.39 to 0.42). The curve is not a cliff. It is a steep climb that levels off around 20% velocity loss. The cheapest fix for junk volume is pushing easy sets to roughly 2 reps from failure, not adding sets, and not chasing maximal failure. (Exactly where to stop, by goal, is in how close to failure should you train.)

And it does invert eventually. Robinson et al. (2024) found hypertrophy rises as sets get closer to failure, with the authors' own caveats attached, since they are load-bearing: the RIR values were estimated from study descriptions rather than measured, model fit was modest, the analysis is described as exploratory, and the paper's conclusion says the exact relationship remains unclear. Either way, every hard set drains recovery. Nippard pegs the benefit as clear up to about 6 sets per session and counterproductive beyond ~6-8. Per muscle per week, 10-20 hard sets is the productive window for most people, though it is not flat across the body: bigger muscles like back, glutes and quads tolerate more (10-12+), while smaller muscles top out around 6-8. A blanket "do 20 sets for everything" prescription manufactures junk volume on the muscles that max out earlier.

One more trap worth naming: ultra-high-rep light sets. Training below ~20% 1RM for 40-50+ reps produces soreness and a brutal pump out of proportion to the actual growth. The burn feels productive. It mostly is not.

How to fix junk volume: make every set count

Stop counting sets. Start counting hard sets near failure. That is the currency Greg Nuckols argues for, and it is right. Total volume load (sets × reps × weight) cannot tell a near-failure set from an easy one, so it is a lousy proxy for stimulus. Here is how to get out of junk volume:

1. Take most working sets to 0-3 reps from failure. This is the practical consensus across Nippard, Henselmans and Nuckols, and it is the first thing to check when someone asks why they aren't building muscle. You do not need to grind to failure on everything. Refalo's 2024 RCT in trained lifters found near-identical quad growth training to failure versus 1-2 RIR (+0.181 cm vs +0.182 cm quadriceps thickness), and the RIR group recovered better. Train hard, not maximal.

1. Fix intensity before adding volume. If your sets are easy, the answer is fewer, harder sets, not more easy ones. Cheapest possible upgrade: take your current program and just push every set 2 reps deeper.

1. Don't autoregulate by strength alone. Robinson found proximity to failure barely affects strength gains (strength was similar across a wide range of estimated RIR, with confidence intervals containing null) while hypertrophy did track proximity. That asymmetry is the useful part of the paper; the precise slope is not. So a lifter who judges effort by "did I add weight to the bar?" can keep getting stronger on the same junk sets while leaving size on the table.

1. Get an objective read on effort. This is the hard one, because RIR estimation is genuinely unreliable. Content sites give you subjective cues: shaking, burning, grimacing (how to know if you're training hard enough separates the useful cues from the noise). Rep-counting apps count reps but say nothing about whether you actually fought for them. The cue that does hold up is question 2 of the test, and it can be measured. Riven is the Apple Watch app that scores muscle failure. It reads your wrist motion and stays quiet during the set; about three seconds after you rack the weight you get the exercise, the rep count and a 0-100 score. Reps slow down as a muscle nears failure, and that is what the score is built on. No barbell clip, no camera, no extra hardware. It shows you which set was the real one. For separating a hard set from a junk one, an objective read beats feel every time. (The evidence that a watch can read this at all is in can an Apple Watch detect muscle failure.)

The whole game is concentration of effort. A leaner program of genuinely hard sets will out-grow a sprawling one full of easy ones, and it will cost you less recovery. Make the sets count, and you can do fewer of them.

FAQ

What is junk volume in lifting?

Junk volume is training volume, sets and reps, that does not add muscle or strength because the sets are too far from failure, too light, or so excessive they hurt recovery. The most common form is easy sets stopped 5+ reps shy of failure.

How do I know if a set is junk volume?

If you could have done 4-5 more clean reps, the load was trivial, or the set was so deep it tanks your next session, it is likely junk. Because lifters overestimate effort, an objective read on how much your reps slowed is more reliable than feel. Riven is the Apple Watch app that scores muscle failure; it scores each set the moment you rack it.

What is the 3-question test for junk volume?

Ask 3 things about the set: could you have done 4 or more clean reps (yes means junk), did your rep speed visibly slow over the last 2 or 3 reps (no means junk), and did the set wreck the rest of the session (yes means junk in the other direction, too much rather than too little). A set that passes all 3 counts as a hard set.

Is more volume always better for muscle growth?

No. Volume helps with diminishing returns and eventually turns negative. Beyond roughly 6-8 hard sets per session (10-20 per muscle per week for most), extra sets add fatigue without added stimulus.

Do I have to train to failure to avoid junk volume?

No. Volume-equated research (Refalo) shows 1-3 reps from failure grows muscle as well as failure and recovers better. The set counts if it is hard, not if it is maximal.

What are junk sets in the gym?

Junk sets are individual sets that end with about 4 or more reps in reserve, use a load too light to fully recruit the muscle, or run so deep they ruin the rest of the session. They count on your log but deliver almost no stimulating reps. The quick test: could you have done 4 more clean reps, and did your rep speed ever slow?

Why don't all my reps build muscle?

The prevailing model says the final ~5 stimulating reps, where full motor unit recruitment and slow bar speed coincide, drive most of the growth, with early easy reps mainly accumulating fatigue. Be clear that this is a heuristic model rather than a directly tested mechanism: nobody has isolated and measured effective reps in a controlled trial. What is supported is narrower: hypertrophy increases as sets are terminated closer to failure, with modest effect sizes.

Sources

• Schoenfeld, Ogborn & Krieger (2017). Dose-response relationship between weekly resistance training volume and increases in muscle mass. Journal of Sports Sciences. PDF
• Robinson, Pelland, Remmert, Refalo, Jukic, Steele & Zourdos (2024). Exploring the Dose–Response Relationship Between Estimated Resistance Training Proximity to Failure, Strength Gain, and Muscle Hypertrophy. Sports Medicine. PubMed
• Refalo, Helms, Trexler, Hamilton & Fyfe (2023). Influence of Resistance Training Proximity-to-Failure on Skeletal Muscle Hypertrophy: A Systematic Review with Meta-analysis. Sports Medicine. PMC9935748
• Refalo et al. (2024). Similar muscle hypertrophy following eight weeks of resistance training to momentary muscular failure or with repetitions-in-reserve. Journal of Sports Sciences. PubMed
• Beardsley, C. How many stimulating reps are there in each set to failure? S&C Research
• Nippard, J. Junk Volume: Why You Must Avoid It For Max Muscle. jeffnippard.com
• Nuckols, G. More is More. Stronger By Science