At some point, if you want to build a no-nonsense physique you’re going to have to lift some heavy pig iron. But bigger and heavier isn’t always better. While there are many workouts where it’s safe to lift heavy weight to maximize their effectiveness, there are just as many that provide greater benefits when you go low and slow. It all comes down to movement selection—performing the wrong moves can be unsafe and a good way to get acquainted with a local orthopedic surgeon.

Let’s take a look at six movements that are unsafe to perform with maximal weights. Be sure to take it easy on these moves to not only avoid catastrophic injuries, but to get the best gains out of them. And remember that training smarter is always better than training harder.