Ask someone in the gym to point to their trapezius muscles, and they’ll probably gesture toward the small mounds nestled between their neck and shoulders—but that’s really just the tip of the iceberg.

Ask someone in the weight room to point to their trapezius muscle, or “traps” in gym-speak, and they’ll probably gesture toward the small mounds of muscle nestled in between their neck and shoulders.

In a recent Reddit thread, natural bodybuilders discussed the exercises that grew their traps the most, with one simple movement standing out as a clear favorite from the 100-plus replies: shrugs. The ...