What does the evidence show?
The optimal number of sets in the weight room depends on whether you want to get big or strong
I’ll admit that I have a weakness for some of the more esoteric nuances of the science of strength. Does having the right levels of a particular amino acid enhance the muscle-building effects of your workout? Can strategically applied bouts of heat boost the signals traveling from brain to muscle? Does it matter to your muscles exactly when you eat? It’s all interesting stuff, but I try to keep in mind that these details are secondary to some far more basic questions. Really simple stuff—like, if you’re lifting weights, how many times should you lift them?
There are some standard answers to this question, as enshrined in documents like the American College of Sports Medicine’s Position Stand on resistance training. But when you drill into the details of how many sets of each exercise you should do, the ACSM’s actual advice tends to read more like an advanced SAT question: “Studies using two, three, four to five, and six or more sets per exercise have all produced significant increases in muscular strength in both trained and untrained individuals. In direct comparison, studies have reported similar strength increases in novice individuals between two and three sets and two and four sets, whereas three sets have been reported superior to one and two.”
With that confusion in mind, I found a newly published study in Medicine & Science in Sports & Exercise, led by Brad Schoenfeld of CUNY Lehman College, to be refreshingly practical—and, better yet, comprehensible. The goal was to figure out what differences, if any, result from doing 1, 3, or 5 sets of each exercise. And the answer, in turns out, depends on what your goals are.
The study involved a total of 34 young men who all had considerable experience with strength training, divided into three groups. They did eight weeks of supervised workouts, three times a week, consisting of a circuit of seven different exercises: bench press, military press, lat pulldown, seated cable row, back squat, leg press, and unilateral leg extension. Each set was done to momentary failure, with the weight adjusted to ensure failure was reached in 8 to 12 reps. The only difference between the groups is that they did either 1, 3, or 5 sets of each exercise in each workout.
The study had three main outcomes, assessed before and after the eight-week training period. Strength was assessed with one-rep max in bench press and back squat. Muscular endurance was assessed by the number of bench press reps the subjects could complete at 50 percent of their one-rep max. And finally, muscle size in four places was measured with ultrasound. (For more details on the protocol, check out Schoenfeld’s excellent blog post on the study.)
The hypothesis put forward by the researchers was that more sets would lead to greater outcomes in all three categories. But that’s not what they found. For both maximal strength and muscular endurance, all three had significant but statistically indistinguishable improvements. Here, for example, are the improvements in one-rep max for bench press:
This is a pretty remarkable finding. First of all, recall that these were experienced weightlifters, all entering the study with a minimum of at least a year of training three times a week. To boost their bench press by close to 10 percent is significant. To accomplish that with just one set per exercise—a full-body workout that took just 13 minutes, according to the paper—is truly remarkable. It was a hard workout, with every set to failure, but not a long one. The five-set workouts, in contrast, lasted about 68 minutes, and didn’t lead to greater strength.
The picture was different for muscle size, though. In that case, there was a clear dose-response effect. The more you lift, the bigger you get. Here’s what the results looked like for biceps size:
For what it’s worth, this is consistent with the conventional ACSM wisdom: “Higher volume, multiple-set programs are recommended for maximizing hypertrophy,” the Position Stand states. So the new results confirm that if you want bigger muscles, the one-set shortcut will only take you so far.
There are some caveats, of course. The results are specific to the particular subjects and the particular protocols tested. For example, if you lift heavier weights so that you reach failure after 3 to 5 reps, which is common for powerlifters, then a single set might no longer be sufficient even for strength gains. More generally, after decades of studies that have produced conflicting results about the optimal combination of sets and reps, we shouldn’t be too quick to assume that the new study is right and all the old ones are wrong. Consider this another brick on the edifice of strength-training knowledge, not the final answer.
The study does strike me as a useful clarification of the some of the confusion I’ve felt in designing my strength training routines. Still, it leaves me with a dilemma. From an athletic point of view, I’m mostly interested in strength as a means to various ends—making me a better rock climber and a more injury-resistant runner and so on. For those goals, a single hard set seems sufficient. From a long-term health perspective, on the other hand, I’d like to increase the amount of muscle I’m carrying around, as a buffer against the inevitable shrinkage of aging. I’ll have to wrestle with that dilemma on my own—without neglecting the even more crucial fact that, for both athletic and health goals, the subtle differences between 1, 3, and 5 sets pale in comparison to the existential chasm between zero and one.
My new book, Endure: Mind, Body, and the Curiously Elastic Limits of Human Performance, with a foreword by Malcolm Gladwell, is now available. For more, join me on Twitter and Facebook, and sign up for the Sweat Science email newsletter.