The short answer to the question “Should I train to failure?” is for the majority of the sets in your training, no, you shouldn't.. While training all out may seem like the no brainer answer to getting stronger and in better shape, the truth is that going to failure too often and never backing off is a sure fire way to prevent progress by digging yourself into a recovery rut. This can not only cause your progress to slow down, but eventually regress due to never allowing yourself to fully recover between workouts. Recovery is just as important as training in regards to making progress. If you’re beginning to stall and you're training extremely hard and are taking almost every set to failure very frequently, the key to making progress again is to back off and begin using what we call reps in reserve or RIR for short, which is the concept of not taking a set to failure and leaving a few reps left in you when you stop a set. It’s important to note that this is more true for the larger compound movements such as the bench, squat and deadlift, but isn’t as important for smaller movements such as barbell curls because these smaller isolation movements produce much less fatigue, even when taken to failure.
Slightly More Progress, Much More Fatigue
When comparing single sets, there is a slight increase in muscle hypertrophy when going to failure versus not going to failure. However, there is also a very large increase in training fatigue. The body becomes better and stronger by first accumulating training fatigue and then recovering from that fatigue. By constantly training to failure on every set, you are creating a very large amount of fatigue that is very difficult to recover from on a consistent basis, yet provides little extra benefit. If you’re under recovering between workouts, each time you go into the gym you’re working at a reduced capacity and performance begins to decrease, making it harder to progress. This will continue until you dial it back a bit and allow your body to recover.
By not going to failure, you’re allowing your body to get a quality training stimulus without the large increase in training fatigue associated with going to failure. Not only is this better for the simple fact that it’s easier to recover from, but it allows you to also get much more work done in the same workout, as you’re left feeling much less tired out after each set when reps are left in reserve. This style of training is much more sustainable over the long run. The more work you can perform and recover from, the more progress you'll make.
Take the graph above as an example. Let's say that your body is able to recover from 15 units of fatigue. This means that you want to cram in as much quality work before you reach your recovery limits in order to maximize hypertrophy. Using the graph as a reference, we can then see that each set with an RIR of 3 would give us 1 unit of hypertrophy and 1.5 units of fatigue. This means that we could perform 10 sets at an RIR of 3 before we reach our recovery limit, netting us a total of 10 units of hypertrophy. Compare this to taking your sets to failure. If you took only 3 sets to failure, you'd exceed your capacity to recover, meaning you'd have to settle for only 2 sets, netting you only 5 units of hypertrophy.
Easier Sets Means More Sets
In my article Understanding Volume & Fatigue, I talk about how the more sets you do, the more hypertrophy you cause. The more sets you do, the more muscle and strength you gain up until a certain point, a point at which you’re doing too many sets to recover from. Because of this, it is much better to train leaving 2-3 reps in the tank for most of your sets than it is to immediately begin going to failure from the get go. By going to failure immediately, you make it harder to continue to perform more working sets due to the fatigue caused by going to failure. Not only will your performance decrease on the latter sets, but if you take those sets to failure as well, you will have a hard time recovering from this workout and will be less likely to come back into the gym fully recovered. It’s much easier to perform 6 sets of squats, for example, if you leave 3 or so reps in the tank each set than if you were to go straight to failure on the first set. By keeping reps in the tank, not only are you able to perform more total work, but it’s far easier to recover from between workouts and thus can be sustained for much longer periods, even making it possible to increase training frequency to further increase total weekly volume. A person doing 20 sets of bench press per week who leaves reps in the tank will make steady progress without high risk of having recovery issues, while a person attempting to perform 20 sets of bench press and going to failure on every set will dig themselves into a recovery rut within a two week period and begin to stall, forcing them to take valuable time off in order to recover from the fatigue.
Training To Failure Has Its Place
Training to failure can be beneficial and used as a form of progressive overload and a way to force progress using a novel stimulus. If you’ve increased your volume near it’s limits, you can occasionally attempt pushing the last set on some of your exercises to failure just to get a bit more training stimulus and recruit more total muscle fibers than you would have otherwise. It’s important that this is only done occasionally and not on every single exercise.
Many routines also include sets where you will perform as many reps as possible (AMRAP) in order to test and/or build strength at different scheduled periods. One example is in the 5/3/1 program where you will take at least one set to failure every workout day, however the routine reserves this for the very last set of a given exercise and is typically only prescribed for that one exercise in a given workout.
It may also be a good idea to go to failure more often right before a scheduled deload if your current routine includes them. By doing this you can cause a stronger stimulus and still be able to recover from it when you take your deload, allowing you to take full advantage of the extra recovery potential you have coming up. The reason this works is because your capacity to recover is drastically increased during due to the upcoming deload; normally you would need to be recovered by the next 28-48 hours in order to continue working out, but because of the deload, you have an entire full week to recover. It only makes sense that if you're going to have extra recovery, you might as well get a slightly increased training stimulus as well to reap the benefits of the extra recovery.
Going closer to and up to failure can also be a good way to get in a better training stimulus when you are strapped for time and can't perform as many sets as you'd like to. Let's say that you typically perform 10 sets on the bench press, but for whatever reason you won't have the time to finish all of your sets. To make up for the lost stimulus from the additional sets, you can take a couple of your sets to failure to reap the benefits, provided you keep your recovery in mind and that the trade off between doing less sets but going close to failure is worth it.
The takeaway is that while going to failure has an important place in training, namely to test strength and provide a more powerful training stimulus per set, it should be used sparingly due to the large amount of training fatigued it causes. The majority of your training should be done with sets leaving 2-4 reps left in you when you rack the bar. Sets going to failure need to have a specific purpose and should be scheduled ahead of time and programmed intelligently in order to allow proper recovery. A failure to properly manage training and recovery is one of the key reasons novices and intermediates (even some advanced trainees) stall.