Hypertrophy in strength training is both a natural and sought out characteristic of strength training. By definition, muscular hypertrophy is the enlargement of our skeletal muscle through two components, which include our muscle’s myofibrillar size, and sarcoplasmic hypertrophy (our muscle’s ability to hold/store glycogen).
Whether you’re a weightlifter, powerlifter, bodybuilder, strongman or functional fitness athlete, hypertrophy is rarely a bad thing when improving strength and supporting performance. And when it comes to muscle hypertrophy and the training that comes along with it, very few, if any, have done more research on the topic than Brad Schoenfeld, PhD, CSCS. He’s a renowned fitness expert who’s published over 100 peer-reviewed articles, and he’s also written multiple books on training and hypertrophy.
One of Schoenfeld’s recent books on hypertrophy was the Science and Development of Muscle Hypertrophy, which is one of the first books/textbooks published fully devoted to hypertrophy and its backing science.
Having been a fan of Schoenfeld’s work and writing for quite sometime, I thought it was only fitting to have him give us some of his science backed rules for hypertrophy training.
1. Sets for Hypertrophy
BarBend: How many sets do you recommend for accruing hypertrophy during a workout? I know this is a loaded question, but are there any guidelines you’d recommend.
Schoenfeld: We carried out a recent metanalysis on the topic that found 10+ sets per muscle per week elicited greater hypertrophy than <10 sets. Thus, this would be a good starting point. It’s important to note that there wasn’t enough research to see if higher volumes would promote even greater benefits. Moreover, research studies simply report the means of subjects; there is always a large inter-individual variability in response, so some will respond better to less while others more.
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A picture can be worth a thousand words. Here are two forest plots from our recent meta-analysis on loading zones. Each horizontal line represents the results of a study. When the black square is to the left of the center line the results favor lower load training; when they're to the right, they favor heavier load training. The diamond below the bottom horizontal border represents the effects of all studies combined. Note that for strength gains, all studies show results to the right of center and the diamond is far to the right, indicating a clear strength advantage to heavier loading. OTOH, note that the hypertrophy results are scattered on both sides of the center line, and the diamond is almost exactly in the middle of center. Take home: Heavier loads clearly are superior for 1RM strength while hypertrophy is equally achieved regardless of the repetition range.
Personally, I feel there is a benefit to periodizing volume so that you push a lifter to the point of overreaching and then pull back on the volume to allow proper recovery. For instance, you might have 10 sets per muscle per week during the first month of a periodized cycle, go up to 15 sets the next month, and then culminate with a period of 20 sets for overreaching – then repeat. There are many ways to integrate the concept into a program, and this must be customized to the individual.
BarBend: Bigger vs. smaller muscle groups, would you recommend structuring sets differently?
Schoenfeld: The term “bigger” and “smaller” with respect to muscle groups is widely misapplied. We just published a paper that noted the triceps actually have one of the largest muscle volumes of all upper body muscles – larger than the pecs. So it’s misguided to use such terms when deciding on volume.
What I would say is that you need to consider the amount of ancillary work that a muscle receives when deciding on volume. For instance, the biceps are involved in pulling exercises for the upper body (i.e. lat pulldowns, rows, etc). Thus, the biceps would necessarily tend to need less “direct” work, assuming all other factors being equal.
BarBend: What’s the recommended amount of reps to facilitate hypertrophy?
Schoenfeld: We recently published a meta-analysis on the topic that clearly shows hypertrophy can be attained across a wide spectrum of rep ranges – as high as 30-RM per set. Provided that the volume load is equated, there does not seem to be much difference in whole muscle hypertrophy between loading zones.
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Cool infographic by Chris Beardsley elucidating the article that I co-authored with @bretcontreras1 on the potential hypertrophic effects of the muscle pump (i.e. cell swelling). This coincides with a couple of excellent presentations at the International Symposium on Exercise Science in Finland this past weekend that discussed potential mechanisms whereby cell swelling may act as a sensor for muscle growth. Still much to be explored on the subject, but in the meantime there is a basis for including some pump training in a hypertrophy-oriented routine.
Now some emerging evidence indicates that there may be a fiber type specific response to training in different rep ranges, with heavy loads showing greater hypertrophy in type II fibers and lighter loads targeting type I fibers. If true, this suggests a benefit to training with both high and low loads to maximize whole muscle hypertrophy. That said, we need more research to better determine the extent to which these effects occur.
BarBend: Can the number of reps needed for hypertrophy change per one’s specific training goals? For example, will a bodybuilder’s idea for hypertrophy/reps differ from a weightlifter, or powerlifter?
Schoenfeld: Most definitely. Muscle strength is maximized when training with heavy loads while muscle endurance is maximized with lighter load training. If these are goals, then the principle of specificity should apply. As noted, for bodybuilders it’s best to train across a spectrum of rep ranges to ensure maximal stimulation of all fibers.
BarBend: For a general guideline, what’s a good training intensity to stick to for hypertrophy?
Schoenfeld: There is conflicting evidence as to how much effort is required for maximal growth. Certainly you need to train with a very high level of effort at least some of the time to sufficiently challenge the neuromuscular system for positive adaptation. That said, the research generally indicates that you don’t need to train to all-out failure to achieve a maximal benefit.
Now the research is somewhat limited on the topic, and I’m still of the opinion that failure training can have a place for advanced lifters to maximize hypertrophy. I like to use the Reps in Reserve technique promoted by my colleague, Eric Helms. This technique provides a way to gauge how many reps you stop short of failure. So in a typical 3-set exercise, I might advocate having an RIR of 2 on the first set, 1 on the second set, and then going to failure on the final set.
When it comes to hypertrophy, more and more research continues to emerge about what’s optimal and what’s pseudo-science. Every athlete will have different needs when it comes to training, and there are a few guidelines you can use to guide your goal oriented progress. Like many in the field, Schoenfeld continues to push the envelope further on what’s fact with hypertrophy, and what’s fiction.
Feature image from @bradschoenfeldphd Instagram page.