Dr. Mike Israetel asks why bodybuilders train to failure. Here's how to prescribe effort per set for a whole client roster.
"Train to failure or not" is the wrong on/off switch. The real question underneath Israetel's case is how close to failure each set should be - and the answer, most of the time, is "close, but with a rep or two in reserve." This breakdown covers his argument in our own words, adds our honest take for programming clients you can't watch train, and shows how to prescribe effort once and reuse it across every client.
By Markus Evers · September 2026 · a Coachway video breakdown
the short version
Israetel's video explains why failure is so tempting - it's an unambiguous signal that a set was genuinely hard - but argues that most working sets are better run a rep or two shy of failure, because that captures nearly all of the stimulus for far less fatigue. The one thing a coach should do about it: stop thinking "to failure or not," and start prescribing a proximity-to-failure target (reps in reserve) per exercise, reserving true failure for the safer movements and the moments where it's worth the cost.
Dr. Mike Israetel - Why do so many bodybuilders train to failure?
Source: Dr. Mike Israetel on the Renaissance Periodization channel - "Why do so many bodybuilders train to failure?". Watch on YouTube. We embed the public video and summarise it in our own words; the video, title and channel belong to Renaissance Periodization, and nothing here implies Dr. Mike Israetel's or RP's endorsement of Coachway.
Who is Dr. Mike Israetel, and why coaches watch
Dr. Mike Israetel has a PhD in sport physiology and is a co-founder of Renaissance Periodization, the company channel this video lives on. He is one of the most-cited voices in evidence-based hypertrophy, best known for turning research on volume, intensity and fatigue into rules coaches can actually program with. For coaches he is close to a default reference for training theory - if a client shows up quoting "reps in reserve" or "stimulus-to-fatigue ratio," odds are it traces back to him. That is the lens this page is written for: not "should I copy his training," but "what does his failure argument mean for how I prescribe effort across a roster." This is a companion to our breakdown of his how many sets per muscle case - that one is about how much you do, this one is about how hard each set should be.
What Israetel actually argues (our summary)
This is our summary of the ideas in the video, in our own words - not a transcript. Watch the original for his exact examples, studies and phrasing.
- 1
Failure is tempting because it's certain. When you hit failure you know beyond doubt the set was hard and the muscle worked - there's no guessing your proximity to failure. That certainty is a big part of why so many bodybuilders default to it.
- 2
But failure carries a fatigue cost. Those last grinding reps add disproportionate fatigue for a small amount of extra stimulus. The framing is stimulus-to-fatigue: you want most of the stimulus without paying the full fatigue bill that failure runs up.
- 3
Most sets belong close to failure, not at it. Stopping a rep or two shy - a low number of reps in reserve - captures nearly all the growth signal while keeping fatigue manageable enough to keep training hard across the week.
- 4
Failure is a deliberate tool, not a default. It fits better on safer, more isolated movements and later in a training block, where the fatigue is easier to absorb - rather than being the setting for every set of every exercise.
Coachway's take
We're fully on board with the core idea, and it's the reframe most coaches need: stop prescribing "go hard" or "to failure" and start prescribing a proximity-to-failure target per exercise. Reps in reserve turns a vague instruction into a number a client can actually aim for - "leave two reps in the tank on your presses" is coachable in a way "train hard" never is.
Where we'd add nuance for a coaching business: Israetel is largely talking to experienced, motivated lifters who can honestly judge how close to failure they are. Your roster isn't uniformly that. A beginner will often stop three or four reps early and swear it was all-out, or blow past failure with ugly form - RIR estimates are unreliable until a client has some training age. So for newer clients we lean on prescribing a rep target and a couple of clearly worded "leave X in reserve" exercises, and we save nuanced RIR autoregulation for the clients who've earned the calibration.
The other coaching-specific point he doesn't have to worry about: he can feel his own set. You can't. You're prescribing effort for people you don't see train, reading it back from a log and a check-in. That makes the safe default even more important - most sets shy of failure, with true failure reserved for machines, cables and isolation work where a missed rep is harmless. It keeps a client who over-reaches from getting hurt on a heavy compound while you're offline.
So our version of his advice is: set a default RIR per exercise, bias compounds toward more reps in reserve and isolation toward fewer, and let RIR drift down as a block progresses. Then - and this is the part that saves your evenings - build that effort scheme into a template once and reuse it, instead of re-explaining "how hard" to every client from scratch.
Prescribe the effort once, then see whether it landed
An effort rule is only useful if it reaches the client and you can check it was followed. That's what Coachway's workout builder is for: build your effort scheme into a reusable template - set per-set rep ranges and write the RIR target into each exercise's notes (leave 2-3 in reserve on the bench, take the leg-curl machine to failure on the last set) - then assign it to a client and adjust from there instead of starting blank. Because clients log every set, client progress tracking lets you read back the actual reps and loads and see whether a client is genuinely training close to failure or leaving far too much on the table - the thing you can never confirm from a chat message alone.
If you want the strategy layer first, the companion breakdown on how many sets per muscle per week covers the volume side of the same equation - how much work you prescribe, at the effort you set here - and our guide to training to failure digs into the mechanics of failure itself.
Effort-per-set cheat sheet (reps in reserve by exercise type)
A default effort scheme you can copy for any client and write straight into an exercise's notes. It biases heavy compounds toward more reps in reserve (safer, more fatiguing) and isolation toward fewer (safe to push, where failure is worth it), then lets RIR drift down as a block progresses. These are our coaching defaults, not figures stated in the video - adjust them to the client in front of you.
Effort-per-set cheat sheet
Default RIR by exercise type
| Exercise type | Default RIR | Train to failure? | Your notes |
|---|---|---|---|
| Heavy barbell compound (squat, deadlift) | 2-3 | Rarely / never | — |
| Other free-weight compound (press, row) | 1-3 | Occasionally, last set | — |
| Machine / cable compound | 1-2 | Last set OK | — |
| Isolation (curls, extensions, raises) | 0-1 | Yes, safe to push | — |
| Machine isolation (leg curl, pec deck) | 0-1 | Yes, ideal for failure | — |
How effort drifts across a block
| Block phase | Compounds (RIR) | Isolation (RIR) | Cue for the client |
|---|---|---|---|
| Early weeks | 3 | 1-2 | "Hard, but crisp - leave reps in reserve" |
| Mid block | 2 | 1 | "Push the last set of isolation harder" |
| Late block | 1-2 | 0-1 | "Take safe isolation moves to failure" |
| Deload | 4-5 | 3-4 | "Way short of failure - recover" |
How to use it: pick the default RIR for each exercise from the first table, write it into the exercise notes, then let the block-phase table nudge effort down as the weeks progress. Newer clients tend to overestimate how close to failure they are - for them, prescribe a firm rep target and only apply "to failure" on the safe isolation moves.
EFFORT-PER-SET CHEAT SHEET (via Coachway) - reps in reserve (RIR) by exercise type. Our coaching defaults, not figures from the video. DEFAULT RIR BY EXERCISE TYPE Exercise type Default RIR Train to failure? Your notes Heavy barbell compound (squat, deadlift) 2-3 Rarely / never Other free-weight compound (press, row) 1-3 Occasionally, last set Machine / cable compound 1-2 Last set OK Isolation (curls, extensions, raises) 0-1 Yes, safe to push Machine isolation (leg curl, pec deck) 0-1 Yes, ideal for failure HOW EFFORT DRIFTS ACROSS A BLOCK Block phase Compounds (RIR) Isolation (RIR) Cue for the client Early weeks 3 1-2 "Hard, but crisp - leave reps in reserve" Mid block 2 1 "Push the last set of isolation harder" Late block 1-2 0-1 "Take safe isolation moves to failure" Deload 4-5 3-4 "Way short of failure - recover" HOW TO USE: Pick the default RIR per exercise, write it into the exercise notes, then let block phase nudge effort down over the weeks. Newer clients overestimate proximity to failure - give them a firm rep target and reserve true failure for safe isolation moves only.
Training to failure for clients - FAQ
Should you train to failure on every set?
No - and this is the core of Israetel's argument. Most working sets are better run a rep or two shy of failure, because that captures nearly all of the muscle-building stimulus while generating far less fatigue than grinding every set into the ground. Training to true failure constantly runs up a fatigue bill that eats into your next sessions and your weekly volume. For a coach, the practical rule is to prescribe most sets close to failure but with a rep or two in the tank, and reserve genuine failure for the moments where it is worth the cost.
What are reps in reserve (RIR)?
Reps in reserve is how many more reps you could have done before hitting failure. A set taken to 2 RIR means you stopped with about two clean reps left; 0 RIR means you went to the point where another rep was impossible with good form. It is a way to prescribe effort precisely without every set being a maximal grind. In Israetel's framing, RIR is the dial you use to trade off stimulus against fatigue - most productive training lives in the roughly 1-3 RIR zone rather than at 0.
Why do bodybuilders train to failure so often?
In the video, Israetel's point is that failure is a simple, unambiguous signal that a set was genuinely hard - you know for certain you left nothing on the table, which is reassuring when the alternative is guessing your proximity to failure. It also reliably recruits the target muscle hard. The catch is that this certainty comes at a fatigue cost, and chasing it on every set is usually more than a lifter needs. The honest read for a coach is that failure has a real place, but as a tool used deliberately, not as the default setting for the whole program.
When is training to failure actually worth it?
Failure tends to be worth its fatigue cost on safer, more isolated movements - machines, cables and single-joint work - where hitting the wall doesn't put a client under a loaded barbell with breaking-down technique. It also fits later in a training block, when you are already pushing hard and about to back off to recover anyway. It is a poor fit for heavy compound lifts, early in a block, or for beginners still learning technique. For a coach, that gives a clean rule: prescribe most sets shy of failure, and pick specific exercises and moments where going all the way is safe and useful.
More training-science breakdowns
- · Dr. Mike Israetel on how many sets per muscle - the volume side of the same equation: how much work, at the effort you set here.
- · Jeff Nippard on how often to train each muscle - the frequency you spread that volume across.
- · The full roundup: fitness YouTubers coaches should study.
Keep dialing in programming
all guidesTraining to Failure: What It Is and When It Helps
Training to failure means a set you cannot extend by another rep. The honest evidence: training close to failure (RIR 1-3) drives most of the muscle growth, while full failure adds fatigue for little extra benefit.
Read the guideDr. Mike Israetel on How Many Sets Per Muscle (Coach's Breakdown)
A coach-to-coach breakdown of Dr. Mike Israetel's volume-landmark advice - MEV, MAV and MRV: what his video actually argues, where we agree and push back for a coaching business, and a copy-paste 4-week volume-ramp planner for programming and tracking clients.
Read the guideRest Between Sets: How Long to Rest (by Goal)
How long to rest between sets depends on your goal: strength 2-5 minutes, hypertrophy roughly 1-3 minutes, muscular endurance under a minute - plus why longer rest can actually support muscle growth.
Read the guideFree tools for this: One-Rep-Max Calculator · Squat Calculator · Warm-Up Set Calculator
Prescribe the effort once, reuse it across every client
An effort rule only pays off if it reaches the client and you can check it landed. Coachway's workout builder lets you template your reps-in-reserve scheme, write the RIR target into each exercise, and assign it in seconds - while clients log every set so you can see whether they're really training close to failure or leaving too much in the tank. Start your 14-day free trial and prescribe effort from one screen.
