The Science of Muscle Growth
I’ve never actually met Brad Schoenfeld in person. But I’ve come to rely on his work. When you read The New Rules of Lifting Supercharged, you’ll see exactly what I mean. He’s codified the muscle-building process in a way that’s both simple and fantastically complex. If nothing else, my vocabulary gets bigger every time I read one of his studies.
Now he has a new book out, called MAX Muscle Plan.
It starts with the information from his studies, and then provides months’ worth of somewhat hardcore workouts, based on his 20+ years as a trainer, during which, he estimates, he worked one-on-one with more than 1,000 people. The range of clients and athletes is breathtaking: Aside from the typical men and women you’d expect to see with a trainer in a gym, he’s been employed by everyone from pro athletes (he’s worked with the New York Knicks and Rangers, along with pro tennis players) to figure competitors and bodybuilders (a sport in which he competed for some 10 years in the eighties and nineties) to nonagenarians.
These days much of his time is devoted to academic work. He’s finishing his Ph.D. at Rocky Mountain University while also teaching exercise science at Lehman College in the Bronx. He fills out his schedule with writing, speaking, and consulting with a select group of elite athletes, mainly physique competitors.
He took time out from his busy schedule — which, frankly, makes mine look I’m semi-retired — to answer a few questions about his work.
Brad, thanks to your studies, in the past two years I’ve probably learned more about what makes muscles grow than I did in the previous 10. I referred to your work early and often in Supercharged. So let me start by asking you this: What have you learned recently that even you didn’t know? What did you find that surprised you?
I think what surprised me most is the lack of research on trained individuals. The vast majority of studies use untrained or “recreationally trained” subjects – who, by all accounts, are in roughly the same boat as untrained subjects.
Why is that an issue?
Well-trained individuals respond differently to intense training than those just starting out. You can’t really extrapolate their results to those with training experience. I’ve made this topic a focus of my doctoral research. I hope to have some data very soon.
Your work has given me a simple way to explain what we do in the gym. We’re trying to 1) generate muscular tension, 2) induce some level of muscle damage, and 3) create metabolic stress. But there’s no question which of those three is most important, right?
Well, mechanical tension is the dominant factor in muscular hypertrophy, to a degree. Without it, there simply isn’t a reason for muscles to adapt and grow.
That said, there’s compelling evidence that a threshold exists, although it’s not clear what the exact threshold is. Once you get beyond it, other factors can be extremely important in the process.
There’s some speculation that, to get a meaningful growth response, you need an intensity of at least 60 percent of your one-rep max. But now some research has challenged this idea.
Based on what we know from research, along with my many years as a trainer and competitor, I believe there’s a “sweet spot” where all these factors can be optimized for muscle development. It certainly makes me think there’s a benefit to training in a variety of rep ranges.
“Muscle damage” is a tricky one to explain. A lot of people avoid training as hard as they should because they’re afraid of the pain. Meanwhile, meatheads like us learn to trust post-workout soreness. We see it as proof that we gave our muscles a new growth stimulus. But what’s the actual connection between muscle damage and soreness? Is soreness a requirement for muscle growth?
It’s a great question. It would take an entire textbook chapter to fully explain the complexities. But for brevity, let’s just say there’s compelling evidence that some muscle damage is “good,” in the sense that it promotes remodeling of muscle tissue, where the muscle ends up stronger than it was before. [If you're not into that whole brevity thing, you can check out Brad's study on muscle damage.]
On the other hand, too much damage impairs remodeling and limits your ability to train. Think of it like getting a suntan: If you stay within the capacity for your skin to adapt, you’ll get a nice tan. If you overdo it, you burn.
Mild soreness probably indicates you’ve set the stage for growth. But a lack of soreness doesn’t necessarily mean you haven’t. Bottom line: Don’t use soreness as a definitive gauge of a good workout.
You’ve worked hard to create a bridge from science to practice. Tell me some of the things that traditional bodybuilding had right all along.
Bodybuilders get trashed a lot for unscientific training — and sometimes rightly so — but we now know that many of the underlying principles are perfectly valid.
For instance, bodybuilders talk about “training for the pump.” We used to say this was just temporary and cosmetic. But now research is showing that the cell swelling responsible for the pump may actually promote muscle growth.
That doesn’t mean that you should train solely for the pump. As I said a minute ago, you really need the full spectrum of rep ranges. But there is a benefit to the pump beyond what you see in the mirror five minutes later
Bodybuilders also realized, intuitively, the importance of variety. Free weights, machines, and cables all have certain advantages and disadvantages when it comes to building muscle, and the disadvantages of one tend to be the advantages of the other. By combining these movements you get a synergistic effect that maximizes results.
Same with training from multiple angles. We’ve known for a long time that muscles like the delts and pecs have separate “heads.” So you can target individual areas of the given muscle. Other muscles like the trapezius have upper, middle, and lower regions that are activated by different movement patterns.
But some of the newer anatomical research shows that the majority of muscles are compartmentalized, allowing for even greater targeting than previously thought.
For instance, the long and short heads of the biceps have subdivisions that are innervated by their own branches of the primary neurons. The upshot is that elbow flexion targets one set of muscle fibers, supination [rotating your wrist outward] targets another set, and combinations of flexion and supination target fibers in between.
This is true for lots of muscles, which only emphasizes the importance of using lots of different exercises in your programs.
What’s the flip side? What are some common practices that, based on your research, don’t make much sense?
One that comes to mind is doing cardio on an empty stomach to maximize fat loss. Fat burning needs to be evaluated over days. You can’t just look at how much fat you burn during the activity itself. Your body is very adept at adjusting how it uses fat for energy. The intensity of the cardio helps determine how much fat you use post-exercise.
So even if you want to argue that you might burn a few more fat calories during fasted cardio – and I have to say, the evidence doesn’t really support the idea – the overall effect on body composition is nil. [Brad wrote a review on fasted cardio for the NSCA's Strength and Conditioning Journal.]
I’ll also say that, while bodybuilders have gotten the concept of variety right in principle, what they do in practice doesn’t always make sense. For example, there’s no evidence that concentration curls give your biceps a better “peak.” Nor will chest flies build your “inner” chest. And leg extensions don’t target the vastus medialis at the exclusion of the other quad muscles. I could go on and on.
Another biggie: the idea that training with high reps gets you “cut.” I actually had a student — an aspiring bodybuilder — insist that this was the case. I tried to explain the physiology to him, and when that didn’t work I gave up and said if he could produce one peer-reviewed study to support his opinion, I’d give him an A for the semester and he wouldn’t have to come to class anymore. Suffice to say, he’s still in class.
Let’s talk about your book. The workouts in MMP are challenging, to put it mildly. In your entry-level workouts, you have beginners doing squats and deadlifts three times a week. What’s the rationale behind that?
There’s actually a break-in phase for novice lifters. It’s a more general total-body routine to develop coordination and build a base of strength and size. If you’re new to lifting, I recommend doing the break-in workouts for up to six months before you jump into the MMP routine.
The phase that you’re referring to is the strength cycle, which comes right before hypertrophy training. You need those heavy, structurally based exercises like squats and deadlifts. I have regular unloading periods integrated into all the cycles to promote recovery and avoid overtraining.
You have some exercises in your book that I haven’t seen since my days at Weider in the 1990s. My shoulders ached just by looking at those upright rows and pec-deck flies. Did you take injury potential into account, or do you figure readers will sort that out on their own?
To paraphrase one of my mentors, the late, great Mel Siff, there’s no such thing as a bad exercise, only bad applications. Much of the issue is in performance.
Funny you mention the upright row. I recently coauthored an article for the NSCA on the exercise with my friend and colleague, Dr. Morey Kolber, who’s one of the top shoulder researchers. Despite the claim that upright rows are bad for the shoulders, there’s nothing in the literature to support that idea. It comes down to performing the move properly — lifting from the humerus, and not allowing the elbows to go above 90 degrees. [Here’s an interview Brad did with the New York Times on the subject.]
The MMP program is extremely flexible. It has well over 100 exercises, and I specifically say that if an exercise doesn’t feel right, don’t do it. Some exercises will have more red flags than others. Machines tend to create issues. Their design doesn’t conform well to individual body types.
But I still think it’s misguided, except in rare cases, to make blanket statements about exercises being inherently good or bad. The principle of individuality applies here.
How do you train in your own workouts? If I watched you work out, would I think, “That guy trains like a bodybuilder”? Or would I see a mix of different philosophies and techniques?
I haven’t competed in a while, and my schedule is extremely hectic. So I’ve modified my training somewhat in recent years. That said, my workouts are still much like the ones in my new book.
I periodize my workouts to give me a variety of rep ranges. I also use step loading, increasing the loads each week – usually for three weeks — within a given rep range. Then I’ll have a one-week unloading phase, where I use much lighter weights. I end up with a wave-like loading pattern to get more stimulation of muscle fibers while allowing for recovery and rejuvenation.
I also periodize training volume. Volume is arguably the most important factor that drives muscle growth. The problem is, consistently high training volumes lead to overtraining. I’ve developed an approach where I systematically increase both the frequency and number of sets over the course of the training cycle. It culminates in a “shock” phase at the end.
If I do it right, I end up with the best muscle development possible.
What do you think our workouts will look like in the future? Will we be doing the same stuff you see now, or do you think lifters will incorporate newer ideas and systems? Or, put another way, what seems cutting-edge now that you think will be common practice five to 10 years from now?
I think we’ll have the ability to write programs for an individual based on his genetic makeup
One thing that really stands out in research is the huge disparity in results you see with individual subjects. Researchers report averages, but in every study you find that some people make hardly any gains, while others are extreme responders.
At some point we’ll be able to take a cheek swab, analyze factors like fiber types and hormonal output, and create a customized routine.
That day is coming, and it’s probably not too far off in the future.
On that hopeful note, I want to thank Brad for sharing his time and knowledge. I highly recommend checking out his website, where he posts lots of great information, along with his new book, MAX Muscle Plan.