This post is taken from the Vitamin. Every Thursday, I drop some knowledge bombs on your face to help you reach your goals faster while avoiding all the bullshit.
When it comes to building muscle, there are a number of factors and variables you need to consider. But none of these matter if you’re not training hard enough.
Broadly speaking, training “hard enough” can be grouped into two categories:
- Training to failure: Each set is taken to momentary muscular failure, where you can’t complete another rep with good form.
- Reps in reserve: You stop the set a few reps short of complete failure. For instance, if your absolute max is 10 reps on a certain exercise, you may stop 2 reps before complete failure. In this example, you were at 2 reps in reserve (or 2-RIR).
You’ll note there’s one common thread between these two approaches: Proximity to failure.
To explore why, imagine you’re in the gym right now doing a set of, I dunno, bicep curls. At first, the weight is moving pretty quickly, and the reps feel easy. But as you keep curling away, you reach a moment where the weight feels heavier, and your reps start slowing down. Eventually, you’ll hit the point where completing another rep takes everything you have before you can’t physically complete another rep.
So what happened here?
When you began the set of bicep curls, your body began recruiting motor units. As the set progressed and you got closer to failure, there was a progressive increase in the recruitment of higher threshold motor units exposing type II muscle fibres (the fibres with the highest potential for growth) to greater mechanical tension––the key stimulus for muscle gain.
Therefore, the idea is if you go take each set to failure, you’re able to recruit all motor units, which will lead to more muscle growth.
However, the research as a whole suggests you don’t need to go to complete failure to reap the muscle growth benefits of the set.
For example, a recent meta-analysis looked at the effects of training to failure vs not training to failure and concluded that: 1
There is no evidence to support that resistance training performed to momentary muscular failure is superior to non-failure resistance training for muscle hypertrophy.
To dive into this a bit more, the upper limit of motor unit recruitment seems to be around 60–85% of maximum force (or one-rep max), which is somewhere around the 6-12 rep range. When training with these (moderate-to-high) loads, high threshold motor units are recruited from the start of the exercise, so there’s no need to go to complete failure to recruit more motor units. 2
With that out of the way, it’s worth noting there’s nothing inherently wrong with training to failure, but it’s something that should be used sparingly for the reasons we’re about to discuss.
3 Reasons to avoid training to failure
1- Training to failure reduces the total volume lifted
If you’re going all out in your first set, you’re zapping energy from your latter sets. This means you’ll either do fewer reps and/or have to reduce the weight. As a result, the amount of ‘work’ you’re doing (i.e. total volume; sets x reps x weight) will be less than if you’d stopped a few reps from complete failure.
To illustrate: Assume we have two lifters, Lifter A and Lifter B, and they’re both lifting 100 lbs.
Lifter A takes every set to failure.
- Set 1: 10 reps → failure
- Set 2: 6 reps → failure
- Set 3: 3 reps → failure
Total volume load (sets x reps x weight): 1900 lbs.
Meanwhile, Person B stops 1-2 reps shy of failure:
- Set 1: 8 reps → Stops 1-2 reps before failing
- Set 2: 8 reps → Stops 1-2 reps before failing
- Set 3: 8 reps → Stops 1-2 reps before failing
Total volume load: 2400 lbs.
By stopping a few reps from failure, Person B was able to maintain better performance across all sets and, as a result, ended up lifting a higher total volume load despite lifting the same weight as Person A, who took each set to failure and saw a performance decrease with each set.
2- Training to failure increases fatigue and recovery time
A meta-analysis conducted by Vieira and colleagues found training to failure led to greater increases in fatigue; specifically, there was a decline in how quickly the weight was lifted, higher muscle damage, and higher RPE scores (the workout felt more difficult). 3
Moreover, constantly training to failure can extend the time needed to recover from a workout even when total workout volume is equated. 4 5
For example, a recent study found participants experienced better recovery when stopping 3 reps from failure (returning to baseline within 24 hours vs 48 hours when training to 1 rep in reserve or failure).
The participants also reported greater muscle soreness, perceived discomfort, and generally felt worse overall when training to failure compared with 3 reps in reserve. 6
All told, training to failure can impact your performance in the current workout but also subsequent workouts. If you’re not fully recovered by the time your next workout rolls around, you may not be able to train as hard, which could hinder progress.
3- Training to failure can increase the risk of injury.
This last point is fairly obvious, so we don’t need to spend too much time on it. If you’re constantly taking each set to failure, fatigue can build up over the course of the set (and workout). As a result, you might get sloppy with form and increase your risk of injury.
Though, of course, context matters. Taking a set of bicep curls to complete failure isn’t likely to increase your risk of injury compared to, say, taking a set of heavy deadlifts to complete failure.
One benefit of training to failure
Although there are several reasons to avoid training to failure, there is one benefit: Training to failure gives you a better idea of how hard you’re really training.
If I told you to complete a set with 2 reps in reserve and explained how to do it, you’d struggle to gauge what that actually means if you don’t know what taking a set to true failure feels like.
On the other hand, if I made you take a set to complete failure and then asked you to stop 2 reps before you reach that point, it’s likely you’ll get close.
To reiterate a point I made earlier, there’s nothing wrong with training to failure as long as you use it judiciously. As such, here are some general guidelines on how to implement it without ending up in Snap City.
- Avoid training to failure on complex, multi-joint exercises (e.g. back squat), but you can safely train to failure on single-joint exercises (e.g. leg extension).
- Instead of taking every set to failure, save it for the last set of an (appropriate) exercise.
- Broadly speaking, the more often you train (>3x/week), the less often you should take sets to failure.
The research as a whole suggests both failure and non-failure training have similar impacts on muscle growth.
But constantly training to failure can lead to reduced performance during workouts, higher muscle damage which can delay recovery, and increase the risk of injury. All of these things could impact your ability to make progress and adhere to a program over the long term.
Taking this into account, it’s smarter to stop 1-3 reps from mechanical failure–where you can’t complete another rep with good form.
That said, training to failure isn’t all bad as long as you’re mindful of how you’re implementing it. Notably, avoid training to failure on complex, multi-joint exercises and save it for the last set of an appropriate exercise. Your training frequency will also influence how often you train to failure; the more often you train, the less often you should train to failure.
- As you get closer to failure, more motor units are recruited, which exposes type II muscle fibres to greater mechanical tension––the key stimulus for muscle growth. Thus, the reasoning for taking sets to failure is that you’re able to recruit all muscle fibres which will lead to more #gainz.
- But the research suggests training a few reps short of failure can lead to just as much growth as training to failure.
- Constantly training to failure can negatively impact training performance and recovery and increase the risk of injury.
- However, training to failure isn’t ‘wrong’ or inherently dangerous–it just needs to be used judiciously. Avoid training to failure on complex, multi-joint exercises and save it for the last set of an appropriate exercise.
- The more often you train, the less often you should train to failure. If you strength train 2-3x/week, you could get away with training to failure more often than someone training 4-6x/week.
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