Despite what you’ve heard, this will NOT mess up your back

Answer quickly: When performing bench presses, should your lower back be arched or flat against the bench?

If you said flat, you’re wrong. But that’s not your fault. A lot of men are taught—incorrectly—that a flat back is best for preventing bench-based injuries.
“There’s a difference between hyperextending your back and creating a natural arc,” says Men’s Health Fitness Director BJ Gaddour, C.S.C.S.

Letting your lower back gently arc allows you to wrap your shoulders around the bench. This improves your stability and lets your chest muscles stretch more for greater muscle activation and strength gains, Gaddour says.
On the other hand, lying flat rounds your shoulders—increasing your risk for shoulder injury—and puts you in a less-than-ideal position to engage your chest muscles, he says. Watch the video to see the difference.