It’s generally true (supported by many studies in the strength and conditioning literature) that you can build mass and strength with any rep range. “Volume” (reps x sets x weight) seems to be the key.
HOWEVER there is a huge “neural” component to strength that a lot of people who don’t powerlift underestimate. I think that’s why it’s important to do low-rep sets if your goal is to lift a heavy single in the near future. Sets of 12-15 or whatever will build muscle just as effectively as doing a bunch of heavy doubles and triples, but won’t train you to fully activate your muscles like the heavy stuff will.
Precisely.
Training with VERY heavy loads for few repetitions (and singles, too) develops the neuromuscular system to engage a maximal muscular force against resistance.
To fire white fibre extraordinarily intensely.
The nervous system of an elite powerlifter, for instance, is profoundly more advanced and efficient than that of the average bodybuilder.
Very often huge bodybuilders cannot display the strength that would correlate with their muscle mass for precisely this reason.
The underdeveloped nervous system, coupled with multiple muscle groups not trained to work in concert (too much isolation/single-joint exercises), results in an inferior maximal strength output than the huge muscles would otherwise indicate.
Put it this way. No matter the horsepower of an engine, if the fuel cannot optimally enter and combustion can’t happen at a fast enough pace, the horsepower won’t be utilized to its full capacity.
Same thing. Basically.
Strength athletes HAVE to train with very low reps and extremely high intensity to develop that explosive ability.
Then there is the psychological component …
I’m simplifying all this, but you get the picture.