For a few seconds, lets imagine this scenario:
It's early in your workout. You’re at the gym in the middle of an intense set of bench press and you’re given two options:
- Stop one or two reps before failure and do an extra set with the same weight as before.
- Do as many reps as you can and have a spotter help you complete the last rep.
Which do you think will be better for gaining muscle and strength?
Surprisingly, it’s the first option, and we’ll get to exactly why in a moment.
But first, for us to understand why this is the case, we have to go over a quick review of what actually causes muscle growth.
What causes muscle growth
The current research on muscle growth shows a few things:
First off, there is an intensity level that we have to pass for the reps we perform to become effective.
In other words, not all volume is equal. It needs to be heavy. For example, a study3 by Brad Schoenfeld compared muscle and strength gains between two groups – a high load group that did 8 – 12 reps per set and a light load group that did 25 – 35 reps per set.
Both groups gained the same amount of muscle, but it was much harder for the light load group.
They were lifting light weight for 30 reps, but the first 20 were only a warm up and were too light to stimulate any real adaptive response (AKA muscle growth). Only the last few reps were difficult enough to elicit enough of a stimulus to actually cause muscle growth.
So while volume is important, overall effective volume is what matters. Just like Greg Nuckols has said:
“From the size principle, we know that sets must be high effort to recruit and fatigue all fibers.
We don’t know the exact threshold for the effort needed to stimulate hypertrophy, and there are plenty of people who experience considerable muscle growth never lifting to failure, but generally it’s necessary to push sets within a few reps of failure.”2
Second, muscle hypertrophy tends to increase with the number of sets we do. However, there is a point of diminishing returns.
After a certain amount of volume (called maximum recoverable volume), each increase has a negative effect. This was shown by a study4 done by Gonzales-Badillo where three groups of weightlifters were asked to perform workouts with different amounts of volume for 10 weeks.
The first group did 1923 reps, the seconds group did 2481 reps, and the third group did 3030 reps. All groups progressed in strength but the second group progressed the most. This suggests that progress has a linear relationship with volume but only up to a certain point. After you pass that point, more volume may have no effect or worse, a negative effect.
Lastly, it’s better to spread your volume over multiple workouts instead of doing everything in one session.
Rastaad and colleagues found this out by studying5 the Norwegian powerlifting team. The power lifters did the same amount of volume and intensity but with different frequencies. Half the team trained six times per week and the other team trained three times a week, but performed double the volume each day as opposed to the other group.
Muscle and strength gains were found to be better in the higher frequency group despite doing the exact same amount of work.
This lets us know that the formula for muscle growth consists of doing a moderate amount of effective reps per week, preferably (but not necessary) with a higher frequency, and while implementing a progressive overload.
When not to Train to Failure
It's not wise to take all of your sets (or the early sets of your workout) to failure. By training to failure, you could be working against this research backed formula.
It can reduce the amount of effective reps you preform in a given workout, thereby affecting your ability to stimulate a hypertrophic response. How? By affecting the total amount of volume you're capable of doing throughout your entire workout.
Considering that muscle growth goes hand in hand with the amount of effective volume you do, you will grow muscle better by preforming more repetitions throughout your workout instead of reps that completely exhaust your muscles by training them to failure.
Another major disadvantage of training to failure is that it puts more stress on your body requiring you to recover longer in between workouts. This can cause you to reduce your training frequency.
For example, you might have had an intense upper body workout on Monday and have another upper body workout scheduled for Thursday. Training to failure on your first session will suppress force production and hinder you during your second workout.
This will negatively affect your training intensity and the amount of reps that you do for the remainder of that training week.
It will also cause you to accumulate more neural fatigue thus forcing you to de-load more often. With more frequent de-loads, you won’t be able to train as effectively during the course of the year.
Does this mean that you should absolutely never train till failure? In short, no.
Training to failure is more effective for muscle growth in one specific situation.
When to train to failure
According to research, when volume (meaning total sets and reps) and intensity (weight you are using) are equal, then training to failure is more beneficial for both strength and muscle growth.
A study1 done in 2005 by Drinkwater and colleagues took two groups of young novice athletes and assigned them a volume of 24 reps on the bench press with their 6 RM (Repetition Max. 6 RM meaning a weight that they could only lift a maximum of 6 reps.)
Group A did those 24 reps in 4 sets of 6 and took every set to failure. Group B did those 24 reps in 8 sets of 3. They used the same weight as the first group, but stopped 3 reps before failure in every set. After 6 weeks, Group A increased strength by an average of 7.3 kg while Group B only did so by 3.6 kg.
This shows that when volume and intensity are fixed (meaning they will be the same throughout the workout), training to failure is superior. The closer the reps are to failure, the more they stimulate the need for adaptation (meaning muscle & strength growth). The last few reps of the 6RM set were the most effective.
Training to failure is beneficial in this circumstance.
Another instance you may want to consider training to failure is during the last set of a particular exercise. In doing so, you may be able to squeeze out one or two beneficial reps that you wouldn’t have performed otherwise. Again, more effective volume will equate to more muscle mass.
That was certainly a lot of “if” scenarios. If you’re lost, here’s a good way to think about training to failure and promoting muscle growth.
The quality of your reps and the total amount of weight you move throughout the course of your workouts are going to benefit you more than simply training to failure.
Training to failure on every set can make your workouts inconsistent and negatively affect your progression from one workout to the next.
So, instead of doing something like this:
Set 1 – 7 reps to failure with 225 LBS
Set 2 – 6 reps to failure with 225 LBS
Set 3 – 5 reps to failure with 225 LBS
It would be better to do something like this:
Set 1 – 5 reps to failure with 225 LBS
Set 2 – 5 reps to failure with 225 LBS
Set 3 – 5 reps to failure with 225 LBS
Set 4 – 5 reps to failure with 225 LBS
You would move more total weight in this scenario, and likely with higher quality repetitions.
As long as you’re making progress over time, (as much as you would probably love to) you actually don’t need to kill yourself on every set to get the best results.
- Training leading to repetition failure enhances bench press strength gains in elite junior athletes.
- The New Approach to Training Volume
- Moderate resistance training volume produces more favorable strength gains than high or low volumes during a short-term training cycle.
- Effects of Low- vs. High-Load Resistance Training on Muscle Strength and Hypertrophy in Well-Trained Men.
- High Frequency Training for a Bigger Total: Research on highly trained Norwegian powerlifters