When it comes to gym equipment, your gym might be trying to kill you. In any commercial facility, you’ll find a sea of cardio equipment and weight machines. Yet it might be the gym equipment that prevents you from achieving the body you want, building tremendous muscle mass, and getting strong.

Worse, the gym equipment could hurt you. Avoid these six machines like a disgruntled Justin Bieber. We chose each piece of gym equipment on this list based on a collection of criteria which magnified their flaws. They train poor movement patterns, develop imbalances, stress joints, and simply do more harm than good. Instead, try the suggested exercises – your body will thank me later.

The below highlights a list of gym equipment and exercise machines that can cause injury or don’t give you the maximum results that you may be able to find elsewhere. Keeping these factors in mind along with the points mentioned above, here are Anthony Yeung’s picks for weight machines to avoid when at the gym.

Seated Twist Machine

Why It’s Bad

At your lower back, the range of rotation of your spine is approximately 13 degrees. (Run to your nearest protractor or geometry teacher.) Yet with this machine, your legs are stationary while your upper body and trunk make huge twists in an attempt to target your core. That puts an enormous strain on the discs and bones of your lower back – you’ll miss those when they’re gone.

If you shouldn’t twist the core to strengthen it, what should you do?

The opposite – resist the rotation.

According to Shirley Sahrmann, a highly-regarded physical therapist, “a large percentage of low back problems occur because the abdominal muscles are not maintaining tight control over the rotation between the pelvis and the spine at the L5-S1 level” [emphasis added].

That’s what we want: tight control.

Try These Instead:

• Palloff Press
• Chops
• Lifts
• Woodchops

Seated Sit Up Machine

Why It’s Bad

To move the weight, you repeatedly flex your upper body, round your shoulders, and yank your neck forward. Worse, you force load upon that movement; I’ve seen people do 90+lbs on those machines! Although you might get some ab work, you’re encouraging and strengthening a Quasimodo posture.

Also, similar to the Seated Twist Machine, it doesn’t train the core in for it’s primary role of anti-rotation and anti-flexion – you’ll get the burn, but you won’t get the function.

Try These Instead:

• Stir-the-pot
• Rollouts
• Bodysaws

Leg Press

Why It’s Bad

A lot of people use the leg press because they hate squatting or just aren’t good at it – it’s also looks great to load a leg press with a lot of 45lb plates and get a few reps (even though you went down about 8 inches).

The reality, however, is that the leg press isn’t functional or safe.

How often do you lay on your back, stay stationary, and push something away with your legs? (Stuck under a car, perhaps?)

Also, the posture of the bottom position isn’t good. Rotate an image of the leg press so that the feet appear to be on the ground and you’ll see a round lower back, excessive torso lean, and failure to break parallel. Imagine squatting and putting a crushing amount of load on that.

Try This Instead:

• Man up and do the squat. (Front squats are my fave.)

Seated Leg Extensions

Why It’s Bad

It targets your quadriceps and only your quadriceps – how could something that means so well do harm?

Your quad always works together with other muscles to extend the knee and never acts in isolation. Picture a sprint or a squat: as the quad extends the knee, so does the glutes to extend the hip and the calves to extend the ankle. Even when you kick a soccer ball, your hips and trunk also help stabilize and generate force.

People with knee issues mistakenly think that strengthening just the quads will reduce their pain. Rather, they should be doing leg exercises that work the different muscles together, but with less range-of-motion. In reality, only targeting the quadriceps creates an imbalance between quad and hamstring; this forces an uneven pull at the knee joint, which may have originally caused the pain.

Try These Instead:

• Reverse Sled Pulls
• Terminal Knee Extensions (cable- or band-resisted)
• Petersen Step Ups

Smith Machine

Why It’s Bad

Let’s use the squat for example:

During a barbell back squat, the barbell will not go down or up perfectly straight. Rather, it might drift forward, backward, or even twist slightly. Yet that’s what makes it so useful – your muscles must work together to control the weight as you go down and up.

The Smith Machine takes all of that away.

It removes your control of the bar. It also fixes you into an unnatural 2-dimensional path. (Need I remind you we live in the third dimension?) In a good bench press, for example, the barbell will drift toward the feet on descent and toward the head as you drive up; doing it on a Smith Machine forces you to lift straight up, which causes unnecessary stress on the shoulders.

Try These Instead:

The free-weight version of the exercise you would do normally do in a Smith Machine:

• A free-weight bench press
• A free-weight squat
• A free-weight deadlift

If you’re worried about safety for the squat, squat inside a power rack and adjust the safety bars to the proper height – that thing has saved my ass numerous times.

Seated Military Press

Why It’s Bad

Overhead pressing is already stressful enough for the average gymgoer – most lack the proper mobility at their shoulders and suffer from postural issues that suffocate their range of motion. I’m not saying that overhead pressing in general is bad — you just have to be smart about it.

Doing the Seated Military Press classifies as “not smart about it.” Much like the Smith Machine, it forces you into a fixed path, which can put added stress on your fragile shoulder area. It also could worsen imbalances – because the weight is fixed for both hands, one arm could be doing more work than the other. As you increase the weight, you might try to generate more force with the stronger side, exacerbating that asymmetry.

Try This Instead:

• Free weight overhead presses with dumbbells

Gym Equipment: The Bottom Line

Try those recommended exercises instead for your next workout. You might find that they’re harder because your body isn’t accustomed to the stabilizing and or movement pattern. Don’t worry – just keep practicing.

Also, notice that a lot of these machines are “seated.” Fact is, we still too much already – at work, in our car, while we eat, etc. Get in the gym and open up your hips; your body will thank us!