Common weight training wisdom holds that there are different optimal intensity ranges for different goals:

• 3-6 reps at 85-90% of your one-rep max (1RM) to build strength (i.e. powerlifting)
• 8-12 reps at 70-80% of 1RM for hypertrophy, a.k.a. bodybuilding
• 15-20 reps at 50-60% of 1RM for muscular endurance (weight training for runners)
• 4-6 reps at 40-60% of 1RM with high velocity for active recovery and certain athletic skills (or power training)

Notably, these are usually cited as being the same — or at least roughly the same — for everyone. Some people will cite advantages of slightly higher rep ranges for women when compared to men, but the overall division into distinct range bands for specific purposes is pretty widely agreed on.

And it may well be that this recommendation is correct on average, but averages can be deceiving.  

Intuitively, many people feel like they perform better at a certain rep range. Their favorite range feels easier, more fun, and they think that they get better results from it.

Now, I’m not usually a “just do what feels right” guy — quite the opposite, in fact.  But in this case, they may be right. Back in 2008, a team of researchers from New Zealand led by Martyn Beaven published what is, in my opinion, the most under-appreciated exercise science study of all time. The key finding of this study? Everyone has an optimal rep range, and there’s a way to test for it.

What Is the Beaven Study, and How Was It Conducted?

The subjects of the Beaven study were 16 amateur rugby players. All of them were male, aged 18-22, had more than two years of weight training experience, and were in the habit of lifting weights for 4+ hours a week.

The study introduced the 16 men to a workout that consisted of four exercises: the bench press, squat, leg press, and seated row. However, there were four variations of this workout: 

• Strength: 3 sets of 5 reps at 85% of 1RM, with 3 minutes rest between sets
• Bodybuilding: 4x10, 70% 1RM, 2-minute rest
• High-Rep: 5x15, 55% 1RM, 1-minute rest
• Power: 3x5 at 40% 1RM with maximal velocity, 3-minute rest

In the study's first week, each subject tested on each of the four versions of the workout on separate days. After the test workouts, subjects then had their testosterone levels tested. For each subject, the workout that resulted in the highest testosterone level was characterized as their best workout, and the one that resulted in the lowest testosterone reading was characterized as their worst workout.  

Related: 3 Benefits of Adding Weighted Sleds to Your Weekly Training

They were fairly evenly split; each of the four workouts was both the best and worst for at least two subjects. That said, there was a tendency for more of them to have strength or bodybuilding as their “best” workout.

The Outcome

Now for the study portion: Eight subjects performed their best workout three days a week for three weeks, while the other eight performed their worst workout. After those three weeks, all subjects had their strength, muscle mass, and body fat tested.  

After that, they switched. The first eight subjects were put on their worst workout for three weeks, the other eight were put on their best for three weeks, and then everyone was tested again. According to common wisdom, the strength workout should build more strength and the bodybuilding workout should build the most muscle.

But that’s not what happened.

Instead, the subjects gained the most strength and mass with their best workout, and the least with their worst workout. In fact, many even lost strength and mass on their worst protocol. This was true even for subjects whose best workout was the high-rep or power workout, both of which are theoretically sub-optimal for strength and hypertrophy.  

What Does That Say About Your Optimal Rep Range?

The most surprising implication is that some people gain more strength on high-rep rather than high-weight protocols, despite the fact that high-weight is obviously “training to the test” better. This is apparently because they gain more mass on the high-rep workout. (In the long run, mass and strength are highly correlated.)

Related: This Is Why Athletes Should Keep a Power Training Day in Reserve

Note that this doesn’t change the fact that strength is partly exercise-specific, so you’ll gain more bench-press strength by bench pressing as opposed to dumbbell chest pressing, for instance.

Another implication is that your optimal intensity/rep/rest range can be discovered by measuring markers of recovery during the hour or so after a workout. It's important to take into account that researchers typically use the testosterone/cortisol ratio as the gold standard for measuring recovery. However, this study got good results measuring testosterone alone.

Should You Pile on the Volume?

The different protocols were not volume-equated — the high-rep protocol was also more sets. It’s notable, therefore, that more volume didn’t always — or even usually — produce the best results, even though more volume is generally considered better when other variables are held constant.

Twelve out of 16 subjects were consistent in their testosterone response to the various protocols, and the four who weren’t were the ones with the least clear results. This method seems to work for the large majority of people, and it’s possible it would work for everyone if the T/C ratio were used rather than testosterone alone.

On a very positive note — and pay attention, because this is the opposite of what most people think — workouts don’t have to kill you. In fact, the most effective workouts are also the ones you recover most easily from, at least where weight/rep/set/rest schemes are concerned.  

Related: This Is the Best Periodization Scheme for Building Strength AND Mass

Finally, the subjects were quite homogenous — all young male college athletes — and yet they showed a variety of best (and worst) protocols. A more diverse subject population would presumably provide even more diverse results.  

How to Find Your Own Optimal Rep Range

Ideally, you would get blood tests post-workout in a totally controlled manner, just like in the study. That’s obviously not practical (unless you’re a professional athlete). Fortunately, there is a “good enough” solution here: Get a fitness tracker.

Most trackers will do fine here, just make sure that it displays your heart rate throughout the day (with the precision of at least 15 minutes or so), as well as heart rate variability.  

As a substitute for blood tests, you can then watch how quickly your heart rate and heart rate variability recover after your test workouts. You might even combine this with a subjective measurement of how recovered (or just how “good” in general) you feel, rated on a 1-5 scale.  

This method will be less precise, but you can somewhat compensate for that by repeating each test workout two or three times and averaging the results.  

This process will take a few weeks of preparation, but your reward for that is that you’ll find a training style that's far more efficient for you, produces better results, and leaves you feeling better after workouts. When you train in the style that works best for your body, you truly can have your cake and eat it, too.