A Plus Set or AMRAP (As Many Reps As Possible) set is a set in which you perform reps until you can no longer get another repetition with good form. These types of sets are seen in many different programs, including the popular 531 program as well as others. While it is typically recommended that the majority of your sets should not be performed too close to failure, Plus Sets still have many uses.
When Should You Use Plus Sets?
While the majority of your sets should not be done to failure and should leave an average of 2 reps in reserve, plus sets do come in handy and have multiple uses. Below I'll list some of the most prominent uses of Plus Sets.
Plus sets can be a great way to test your current strength levels. If you're always leaving reps in reserve and never taking any of your sets to failure, it may be hard to really gauge just how strong you currently are. Occasionally taking a set to failure can be a great way to periodically test your strength levels on a given exercise. This way you can determine whether your overall training is going in the right direction. You should see an increase in strength levels over time, so testing periodically is a great idea.
If you've been using RIR or RPE to gauge the intensity of your sets, there's a solid chance that your estimations are not entirely accurate. What you think is an RIR of 2, may actually be an RIR of 3-4. By taking a set all the way to failure using a Plus Set, you can see how many reps you can truly get with a given exercise and load, rather than having to estimate. Periodically doing this can help you maintain a true RIR/RPE and get the desired stimulus from your training more consistently. The last thing you want is to unexpectedly be training with an intensity level that is far below what is required to cause a hypertrophic response.
Create A Stronger Stimulus
If you're edging up near a deload week and can afford the added stimulus, it may be a good idea to push the last set on a few of your exercises all the way to failure to generate a stronger stimulus. This will increase the amount of fatigue generated by those sets, but because you have a deload coming up, you should not have problems recovering. The closer you train to failure, you more stimulus you can generate. So it's a good idea to use Plus Sets near a deload to squeeze out a little more stimulus before your improved recovery period.
Low Volume Training
Both volume and proximity to failure affect how much training stimulus you can produce, so if one is lacking, you can increase the other to make up for it. If you're only able to train with low volume (whether by choice or your life schedule), taking some of your sets to failure can be beneficial to make up for the lower volume levels. Despite the increased fatigue generated from Plus Sets, recovery shouldn't be as much of an issue due to the lower overall volume you're training with.
Things To Avoid With Plus Sets
When you do decide to implement plus sets into your routine, there are some things you should watch out for. Plus Sets are not without their drawbacks and there are a few things you'll want to avoid.
Avoid Using On Initial Sets
When doing plus sets, make sure not to perform them on the very first set of an exercise. This is due to how fatiguing plus sets are. Doing a plus set first in a workout will likely fatigue you enough to cause a decrease in performance for the following exercises. A better method is to use on the last set of the last exercise of a muscle group.
Use Infrequently On Compound Movements
Because compound movements are harder and more fatiguing already, doing plus sets on them too often can be a recipe for recovery issues. You'll like want to avoid doing plus sets on large lifts like the Bench, Squat and Deadlift frequently. You'll likely not want to exceed 1-2 plus sets per compound movement per week. And even that may be pushing it. You'll probably be best off with 0-1 plus set per week on compound movements in general and very rarely do them on the Squat and Deadlift.
Avoid Doing Them Early In A Training Cycle
For those who plan their training ahead of time and use mesocycles (you should), you want to avoid using plus sets early on during the cycle. The goal of a mesocycle is to accumulate training stimulus and make it to the end of the cycle without needing to take a premature deload. Training to failure too early on during a cycle can hinder your ability to continue training and make it to the end of a cycle without needing to take time off for recovery, impacting your long term progress. Since most mesocycles ramp up in intensity and/or volume, it's best to place your Plus Sets towards the end of a mesocycle.