What is RPE? There is a lot of research backing RPE as a way of autoregulating workouts. We can go as deep as we want, and often the conversation can get really complex. Here's what we really need to know: On a scale of 1 - 10, how hard was the last few reps of the set? In theory, an 8 RPE would mean we would have only been able to do 2 more. 7 would mean 3. That's what the Left In Tank column means. Anything over an RPE of 6 has got us in the "applying enough stress to this specific tissue" range. Those are the sets we want to count.

Don't worry about it being super accurate, when we're first starting out, anything we do is adding benefit. As we progress, what we can handle will increase, as well as our ability to judge what we can handle.

This is the important thing. Stress applied to the tissue. Sets, workout structure, implement - they are all indirect ways of affecting stress, and, ultimately, arbitrary.

How many sets?

Research is pretty clear on this. Hard (sufficient RPE) sets per week is the main driver of adaptation and more important to focus on than sets per workout or reps per load.

How many? If we listen to nothing else, listen to this: Even one hard set per muscle group a week puts us on the positive side of 0.

That being said, research, in general, suggests 10-20 sets per week, per muscle group. That's really not a lot. That's a good thing. That's more time to spend filling our overall activity bucket with other activities we may enjoy more. Also, the amount of sets needed can very greatly from individual to individual. One person may need 5, another person, 25.

Keep in mind that we don't get bonus points for how "hardcore" our workout is. Our muscles can only grow so fast. Once we cross "enough" to elicit an adaptation, every additional set has diminishing returns for our progress and increasing demands for our recovery time. As with all things human, where this threshold resides is greatly variable between humans and can even vary greatly within the same human, depending on the circumstances. Any blanket recommendation is ultimately arbitrary and is more likely to waste someone's time or be harmful than to be correct.

Here's my not blanket suggestion. Start low. If you're new, had a long layoff, or just new to this type of lifting, Start at 1 hard set a week per muscle group per week. If you've been working out lately, start at 5.

Every couple of weeks, add a set or 2. When you get to a point where you notice you're achy consistently, overly tired, abnormally moody, or your performance is dropping, drop your sets and start over.

If you can do that consistently, because you're "chasing" the correct variable - RPE, rather than arbitrary proxies like rep number, even on the back off weeks, we are making progress.

More accurately, how often should we work a muscle group per week?

There's a signicant body of research on this topic, as well. 2 times a week is slightly better than once a week, although once is still great. 3 is even slightlier better than 2. After that, it seems to matter less and less. Importantly, when sets per week is accounted for, there is not much difference between any of the frequencies.

For whatever reason, this causes an uproar in the fitness community. On one side you have newer, 6 day a week, high frequency gurus saying, "lower frequency is not better" and that this research means high frequency is magic and everyone should do it.

On the other side you have the more traditional, lower frequency folks saying, "higher frequency is not better" and everyone should stick with lower frequencies.

Both groups are wrong. The correct way to read the research is, "one is just as good as the other."

That subtle distinction is not something to argue over. It is a beautiful thing. Now we have almost unlimited organizational options to fit our schedules and preferences.

When we realize that the important varaible is sets per week, we can divide that however we want. Let's look at 2 different recent real-life scenarios as examples.

Scenario 1: Coming back from an extended layoff.

We are going to start with 5 sets per muscle group per week. We are working out 5 days per week.

With this person, I'm probably going to hit one hard set per group everyday. It's enough to feel like a good workout without overwhelming them, and it's routine enough to facilitate habit formation and skills acqisition.

If we like this routine, we can really run with the format as long as we want. Once we are up to 3 sets per group, per day, we are at 15 sets per week. It's still a reasonably timed workout and low enough volume every day that it won't hurt your subsequent workouts uf you are rotating exercises within a muscle group. If you start feeling fatigued, or notice a sustained drop in performance, it might be time to split them into different days.

Scenario 2: We are gonna work out 6 days a week. We are going to start with 12 sets per week. We really like to feel a pump in our upper body, but we are at a point where we dread the thought of a bunch of sets of leg work.

No problem. We are just going to run our upper body and lower body at different frequencies.

For our upper body, we will run an push/pull split, where we work push 3 days a week and pull 3 days. That gives us higher volume on those days to feel a little more "pumped." 6 sets per workout to be exact.

For our lower body, we are going to hit it every day, so it's the same volume throughout the week, but less per workout. 2 hard sets of legs per workout is a lot easier of a mental hurdle.

There are almost infinite possibilities. Play around with it. Set our total for the week and then divide it between the number of times we want to work out. If we don't like one of the exercises, pick another from the same group. It's all the same. It's about the stress we are applying not the exercise choice.