But equally, failure isn't something you should always avoid.

Here is exactly how hard to train if you want to maximize muscle building based on latest scientific evidence.

Welcome back, Dr. Milo Wolf here today, PhD in Sports Science with Wolf Coaching, breaking down how hard to train to maximize muscle growth.

Your first question heading into this video might be, should I be taking my sets to failure or not?

The truth is, that is not the most helpful question.

Instead, we need to reframe it in terms of how close to failure you should be training.

Instead of simply dichotomizing things into you're training to failure or you're not training to failure, it's more helpful to look at things in terms of repetitions in reserve.

How many more repetitions could you have done with good technique before you simply couldn't lift the weight anymore?

That's where the concept of repetitions in reserve comes in.

It's simply something you can think about when you're doing your sets.

If you think you could have done 2 more reps before reaching failure, you had 2 repetitions in reserve on that set.

Why is this important?

Well, for one, taking a set to 2 repetitions in reserve vs 10 repetitions in reserve will not have the same effect for muscle building.

While you're not hitting failure in either case, one of those two sets is going to be more effective, the one where you go to 2 repetitions in reserve.

And secondly, this concept of repetitions in reserve is how we've looked at training to failure vs not training to failure in the research to determine exactly how close to failure you should be training to maximize muscle building.

And using exactly this concept of repetitions in reserve, a meta regression last year by Robinson and colleagues looked at how the effectiveness of a given set changes as you go closer and closer to failure.

In other words, you have fewer and fewer repetitions in reserve.

They looked at all the studies where they were able to find out how many repetitions in reserve were participants training with, amongst different groups.

And when combining all of those results from a variety of studies, here's what they found.

The closer you take a set to failure, all else being equal, the more hypertrophy that set will cause.

Importantly, these results are somewhat at odds with previous research.

Previous meta-analyses had found potentially a small effect of going all the way to failure vs not going to failure.

But importantly, these previous review papers had the flaw of simply dichotomizing as I mentioned earlier.

But all in all, when you take this review paper by Robinson and colleagues alongside other review papers performed in the past, the picture emerges that the closer a set is taken to failure, the more hypertrophy is observed.

So take every set to failure.

That is the video I will see you- wait a minute, no, that is not the video.

Because while taking a set closer to failure does seem to lead to more muscle growth on a set-per-set basis, taking a set closer to failure also is more fatiguing.

And because your body can only recover from so much fatigue in a given training week, we want to make sure we're actually getting sufficient bang for our buck here.

We're not just getting a lot of fatigue for not much additional stimulus.

Because yeah, training closer to failure and to failure is more fatiguing than training further away from failure.

And that's exactly what a study by Pareja Blanco and colleagues from a few years ago found.

In this study, they had participants train with somewhere between their 4-12 repetition maximum.

Essentially, a low that they were able to lift for 4-12 reps in an all-out effort before they hit failure.

And essentially, with a variety of loads ranging from a 4-rep max to a 12-rep max, they had participants perform both all-out sets to failure and submaximal sets, where they left somewhere between 2-6 repetitions in reserve.

Then after they had participants perform these different tests, they also measured their fatigue in a variety of ways.

From more physiological markers of muscle damage for example, like creating kinase levels, to more performance-based outcomes, like how much weight they were able to lift at a certain velocity, which is tightly correlated to your performance day-to-day, and therefore, your recovery.

Indeed, in sports science terms, recovery is typically defined as a return of performance to baseline pre-disruption.

And basically, training all the way to failure caused a lot more fatigue both in terms of physiological markers, like creating kinase, and also in terms of performance outcomes.

This was apparent in both the bench press exercise and in the squat.

Lifters both experienced more fatigue immediately after the session, when they trained to failure versus not training to failure, as well as 6 hours after the session, a day after the session, and even 2 days after the session.

And so, training to failure does seem to be more fatiguing alongside also being more stimulating for hypertrophy.

Now, one reservation I had in the past is that I thought that training to failure might be something you get used to.

In other words, when you first train to failure, you get really tired and gassed out.

But then, as you keep training to failure week after week, maybe it's something you get used to, and the additional fatigue diminishes over time.

Your body has a set of mechanisms in place that we've coined the repeated bout effect to prevent excessive fatigue when you're repeatedly exposed to the same stimulus over and over again.

However, unfortunately, you may not actually get used to this over time.

That is according to a recent study by Raffaello and colleagues.

Using a within-participant design where participants trained one leg one way and the other leg another way, they were comparing training all the way to failure with one leg to training with 1-2 repetitions in reserve with the other leg.

For both legs, they were doing single-legged leg press followed by single-legged leg extensions.

The only difference was that one leg was training all the way to failure and the other leg keeping 1-2 repetitions in reserve on all sets.

And this study had a few interesting findings.

First, when training to failure, the drop-off in performance from set 1 to the last set of an exercise was larger compared to when they didn't train to failure.

In other words, the fatigue generated from training all the way to failure impaired performance on subsequent sets more compared to when they just kept 1-2 reps in the tank on those earlier sets.

And importantly, that additional fatigue generated from set 1 to set 3, for example, maintained throughout the study.

So at all points throughout the study, the leg that was trained to failure had a bigger drop-off or bigger fatigue essentially from set 1 to the last set, suggesting that failure isn't something you can get used to altogether.

It is still going to be more fatiguing even after 8 weeks of training as it was in this case.

In addition, in this study, they broadly observed similar muscle growth whether sets were taken to 1-2 reps in reserve or all the way to failure.

When you zoom in further into the results, I think there's a couple of potential things you can also glean.

Number one, the difference between 1-2 repetitions in reserve and truly going all the way to failure might be too small to really be able to detect in a relatively small sample.

Going back to the meta-analysis by Robinson and colleagues earlier, we do expect more muscle growth from a given set the closer you go to failure.

However, this difference isn't going to be huge when you're talking about a set taken to 1-2 reps in reserve and a set taken to failure.

And so in the context of this study, we may just not have had sufficient statistical power to detect any differences in muscle growth.

Secondly, if you look at the muscle growth results closely, there is a potential interesting finding here.

Now keep in mind, in this study, participants started with a leg press followed by a leg extension.

Additionally, the leg that was being trained to failure experienced larger fatigue than the leg that was being trained submaximally.

So if training to failure was causing so much fatigue that it could actually impair hypertrophy down the line, we would expect less muscle growth stemming from the leg extension in the leg that was training to failure.

By the time they got to leg extensions, they had already performed leg press to failure and they were quite fatigued.

And therefore, we might expect the leg extension to have become less effective for hypertrophy than if you just kept a few reps in the tank earlier in the session.

And they may or may not have found this.

So the leg press is a much better exercise for targeting the vastus muscles, or the vast thigh muscles, of the quadriceps.

That is because those muscles only perform knee extension.

So whether you're doing a compound exercise or an isolation exercise, they're going to be trained effectively.

However, the fourth head of the quadriceps, the rectus femoris, is best targeted during isolation movements like a leg extension.

That's because while it does knee extension, it also does hip flexion.

So when you're doing something like a leg press or even a squat or a lunge, you're shortening it at another joint.

And this dynamic generally doesn't lead to the best growth.

For instance, in a study by Kugel and colleagues, they found minimal rectus femoris growth when just doing the squat.

And in this study, they potentially observed slightly better vastus lateralis growth when training all the way to failure, but slightly worse rectus femoris growth when training all the way to failure.

Suggesting that the additional fatigue generated by going to failure too early in that session for that muscle might have interfered with the second exercise and how effective that exercise was.

And so potentially, going too close to failure too early into a session might actually impair hypertrophy on those subsequent movements and subsequent sets.

Before we move on, I want to clarify that the difference in terms of rectus femoris growth and vastus lateralis growth was very small.

But it makes sense to expect this sort of finding.

So I do think it's something we probably want to keep in mind.

At the very least, if we want to hedge our bets, it may be worth reserving failure for a little bit later in the session.

Whenever we choose to train to failure, there is the opportunity cost of, for example, doing more volume.

Doing more volume will also cause more muscle hypertrophy, but it is also more fatiguing.

So we have to pick one.

Which one do we pick?

Training close to failure or doing more volume?

Let me give you an analogy so you can understand how volume and training close to failure impact your body.

Your body is kind of like a sink.

There is a drain pipe that gets the water to leave, and there is a tap that you turn on to fill the sink with water.

The amount of water being let into the sink through the tap is essentially how much fatigue your training is generating.

If there's too much water coming in, eventually it will overflow and cause a shit ton of a mess.

And that's where the size of your drain pipe comes in.

The bigger the drain pipe, the more water can exit the sink, preventing it from overflowing.

And in this case, the size of the drain pipe is essentially your body's ability to recover.

Which can be influenced, for example, by how well you sleep, how good your nutrition is, and so forth.

But ultimately, there's only so much bigger you can make your own drain pipe through things like good nutrition, good sleep, and so forth.

At some point, you just have to control how much water you're actually putting into the sink to begin with, otherwise it will overflow.

Now, both doing more sets in the gym and training close to failure will increase how much water is flowing into your sink.

But since both of those things cause more hypertrophy, that is fine.

We just want to be mindful of which one we pick given that there's only so much water we can put into the sink at once before it starts overflowing and shit goes south.

You need to pick your poison.

You can't be maximally pushing volume and maximally pushing relative intensity at the same time.

There is always some give and take.

Whenever you're making training decisions, just keep this dynamic in mind.

If you're pushing your sets closer to failure all of a sudden, just keep in mind you might need to lower the number of sets you're doing.

With that being said, most people can recover from much more than they think they can.

And in fact, reported cases of overtraining within the literature are remarkably rare.

But so, which one should you prioritize?

Should you be doing more and more sets to get more hypertrophy, or should you be taking your existing sets closer to failure?

Well, there is a meta-analysis coming out soon by the guys over at Data Driven Strength that should give us some answers in that regard, but in the meantime, here is my attempt and my practical advice to you as to how close to failure you should train and how many sets you should be doing.

The aim here is to get the best of both worlds.

If you want to maximize muscle growth for a given muscle and you've been training for more than about 6-12 months, there's a good chance you'll need to do 20-30 sets per week per muscle to really maximize hypertrophy.

And yes, those sets are close to failure.

Some people in my comments always be talking about there's no way you can do that much volume or train close to failure without overtraining.

You haven't tried it potentially.

Maybe that's a you problem, cause I don't seem to be having an issue.

What I'm saying is, it's time to start grinding.

So generally, if you've been training for a while, I would start with training most of your muscles around 15-20 sets per week per muscle and see how you do.

If you want more growth and you're responding reasonably well, feel free to increase it closer to the 20-30 set per week per muscle range.

As far as how close to failure to train, I think we want to get the benefits of training close to failure without getting to the downside of getting more fatigue in.

And the following is my attempt at getting just that.

Whenever you're training for muscle growth, start the first set of an exercise a bit further from failure, for example at 2 repetitions in reserve.

Then as you perform each subsequent set on that exercise, inch a little bit closer to failure, maybe all the way to failure on that last set.

That way, you get to maintain a high level of performance by not going to failure too soon in that exercise and fatiguing yourself for the subsequent sets, but you also get the benefit of 1.

Training pretty close to failure on average, and 2.

Getting at least 1 or 2 exposures to true failure on that last set or two.

Next, if you have multiple exercises targeting the same muscle groups on a given day, I would generally reserve failure or training very close to failure for those last exercises.

For instance, if you're doing both a barbell bench press and a dumbbell fly on the same training day, if you're starting with a bench press, consider going from 3 reps in the last set for the bench, and then starting the dumbbell flies around 2 reps in reserve and going all the way to failure on that last set.

That way, you'll still be performing well on the dumbbell fly, but you're also getting the benefit of training to failure on that isolation movement.

A third guideline for how close to failure you should be training is to consider context.

I train Monday through Friday.

I train 5 days a week.

There are going to be days where it's wiser and less wise for me to go all the way to failure.