There are a few myths about lifting heavy that I want to clear up.
First, lifting heavy will not make you bulky. Sitting on the couch eating pizza and wings and guzzling beer will make you bulky. :-) Lifting heavy gets you strong and helps you avoid injuries.
Second, heavy lifting won't get you hurt. Following a well-designed program with a coach who makes sure you're doing the movements correctly is safe. Being weak and imbalanced is what gets you injured.
WHAT "HEAVY" ACTUALLY MEANS
When I say heavy, I mean heavy relative to you. A 200-pound guy who's been lifting for five years will obviously squat and deadlift more than a 120-pound woman who started yesterday. Heavy is personal.
WHEN SOMETHING HURTS, "GO LIGHTER" IS LAZY
If a movement hurts and a trainer just tells you to "go lighter," that trainer isn't doing their job. The problem might be the movement pattern itself, not the weight on the bar.
When there's pain, ask two questions. When does it happen, during the lifting phase or the lowering phase? And how bad is it on a scale of 1 to 10?
If the pain shows up on the way up, sometimes we focus on just the lowering portion. With an elevated pushup, for example, lower to the bar and step a foot forward to assist yourself on the way up. Bands are great for deloading too.
Pain that's a 4 or less can usually be trained around. A 5 or more means it's time to modify. But going lighter isn't the only option. Keeping the weight challenging while limiting range of motion works too.
So let's stop treating heavy as bad and light as good. There's a time and a place for both.