Enter any commercial gym and you’ll likely come across a Smith machine (named after Rudy Smith, the gym owner credited for turning the machine into what we know it as today). The machine features a barbell attached to a large metal frame via a vertical fixed-track rail system that basically acts as a spotter when you’re working out solo. (Pegs lock the bar in place, so if you get stuck during a move like a bench press, you are still able to exit the machine safe and sound.) 

Sounds great, right? In theory, sure. However, many fitness professionals have mixed feelings about the Smith machine. Here’s why the Smith machine is so controversial, which moves it is and isn’t suited for, and how you can effectively incorporate it into your workout. 

Why is the Smith machine controversial?

Turns out, fitness pros are justified in their disdain for the Smith machine. “It’s not really an optimal piece of equipment to use for resistance training. No matter what exercise you’re doing, your movement pattern will be on a fixed path,” says Katie Kollath, ACE-CPT, co-founder of Barpath Fitness. “This doesn’t really carry over much to daily life and doesn’t mimic how your body is supposed to move.” 

While you only move directly up and down when using the Smith machine, you see, that’s not how it works when you’re carrying groceries in from your car or picking up a giant box in your basement. Those movements are much more dynamic—and require your body to engage stabilizing muscles that the Smith machine just doesn’t fire up. 

Read More: 5 Strength Moves Everyone Should Do

The Smith machine can also pose some risk of injury, Kollath adds. While most other fixed path machines—like the chest press machine—also provide support for your back, the Smith machine does not. “Since the bar on the Smith machine moves on a fixed track, it could produce unnatural movements, and potentially encourage someone to flex or extend the back too much based on how they’re built, where their feet are, or how they need to move,” she says. “So, essentially, it can solidify bad form—especially for beginners who don’t know much about resistance training.” 

As anyone who has ever experienced it knows, incorrect form can lead to painful back injuries, like a herniated disc. At best, these injuries take you out of the gym for a bit and, at worst, can land you in the doctor’s (or even surgeon’s) office.

Exercises You Shouldn’t Do On The Smith Machine

Now, you’re likely wondering what exactly you should avoid when using the Smith machine. Well, many fitness pros would argue it’s never really the optimal choice for weighted moves. “Using the Smith machine over a barbell is pretty much always the wrong choice,” says Kollath. “You will recruit way more muscle fibers utilizing free weights and contracting more muscle fibers means better results—more muscle and strength!” (Consider looping in an experienced gym-goer friend or personal trainer to get your form right, if that’s what’s holding you back.)

If you’re still interested in incorporating the Smith machine, you’ll definitely want to avoid using it for squats and deadlifts because of the risk of back injury, Kollath says. She also doesn’t recommend it for other compound lifts (exercises that require multiple joints to move in harmony), like overhead presses, bench presses, lunges, or rows. 

Exercises You Can Use The Machine For

Still, the Smith machine can be a useful workout tool for very specific movements. “With my clients, I like to train pushups and inverted rows on the bar,” Kollath says. “It’s a great way to train pushups for someone who doesn’t yet have the strength to do full-range-of-motion reps on the floor.” You might start with the bar positioned up high to make the movement easier and then gradually move it down notch by notch as you get stronger. “It’s a nice way to have some objective feedback for building pushup strength,” she says. 

Read More: 5 Pushup Form Mistakes You Might Be Making—And How To Fix Them

The same idea applies to inverted rows, in which you hang below the bar and pull your bodyweight up. (They’re a great exercise to do when working towards pullups.) As with pushups, you can start with the bar high and your body angled beneath it and gradually lower the bar and move into a more inverted position.