The Burn and Size Gains
Q: For hypertrophy, is the "burn" or the "pump" necessary?
A: There's a lot of ways people increase hypertrophy. Look at an Olympic weightlifter who never gets a pump. Look at a strongman competitor. They still hypertrophy.
The best studies on hypertrophy were done in Finland. They found that wrestlers, bodybuilders, powerlifters, and weightlifters all hypertrophy... but for different reasons. So the most important thing for hypertrophy training is to actually do varied training. Look at Ronnie Coleman. He used to train as a powerlifter then he trained as a bodybuilder: varied training.
Look at pre-1980's bodybuilders, back when the steroid usage was fairly light compared to today. Back then they trained as part of a subculture with weightlifters and powerlifters. By society's standards, people who lifted weights were weirdoes. So all these people lifted in the same gyms and shared training methodologies.
I saw Robbie Robinson train in Norway with a Norwegian powerlifting and bodybuilding champion. Robbie, especially for his age, is a strong dude. He was kicking this young guy's ass. You could tell these guys came up in a culture where you learned to lift more to get bigger. These days I've seen pro-bodybuilders curling with 35 pound dumbbells, but they still have high levels of hypertrophy.
The forgotten element of hypertrophy training is the principle of overload. People don't try to lift heavier, they just double their drug dosage.
So, "going for the burn" is one way to hypertrophy, but not the only way. For example, if I make you do eccentric squats and eccentric chins, you're going to put some weight on, but you don't have a burn.
Hypertrophy is a function of load vs. time under tension. Since it's a product, you can work at one end or the other, or both. Let's say you can squat 135 pounds for ten. Well, if you squat 135 for 30, then your legs will grow. But if you squat 225 for ten then your legs will grow too, but for a different reason. And if you can then do 225 for 50, then you're legs will really get big!
Both systems work.