There are certain pieces of exercise equipment that I wish didn’t exist. Or at least I wish there were big signs on them that said, “By using this piece of equipment, you are wasting your time.” These machines are non-functional and some increase your risk of getting an injury. Here are five of those machines that you should leave out of your routine.

Adductor/Abductor Machines –  Not only can using these machines look a little awkward, but they are ineffective at developing the muscles that they say they are going to strengthen. These machines are geared to work the adductor muscles (inner thigh) and the abductor muscles (outer thigh) in isolation. But the reason these machines are ineffective is these specific muscles are meant to work in coordination with the rest of the body to stabilize the legs. And talk about an exercise movement that is not functional. I’m pretty sure moving your legs in and out like that has no real application in everyday movement or any sport.

Try this instead: To effectively strengthen these leg muscles, consider doing exercises in the frontal plane (side-to-side). Include side lunge variations or sumo squats. If you have been strength training for some time, add single-leg exercises into your routine. Single-leg exercises, like single-leg squats or reverse lunges, are fantastically effective at engaging the abductors and adductors.

Treadmill at too High of Incline – Walking is a great form of cardiovascular exercise and adding an incline is a great way to strengthen your legs and increase your caloric burn. But if you put the speed and incline so high you have to hold on to the handle-bars, you have now taken a great exercise and made it a lot less effective. Holding onto the handlebars creates improper alignment and can cause back problems or other injuries. Holding on also reduces the amount of calories you are burning because you’ve transferred the workload back to the machine.

Try this instead: Decrease the speed or incline and focus on walking at an intensity that you can maintain with proper form. If you want to build up to faster speeds and higher incline, add intervals into your walking routine.

Seated Rotation Machine – Rotation movements occur in everyday life and especially in certain sports. So it makes sense to want to perform exercises that have you rotate. But when you take a seat on the seated rotation machine, the hips are now locked into place while the upper body twists. Your body wants and needs to use your hips during rotation or else the brunt of the force is placed on the lower back. The seated rotation machine places extra stress on joints and muscles that aren’t made for that kind of movement or impact. For this reason, the seated rotation machine isn’t beneficial for helping you with your sport or getting you stronger muscles, and it may even lead to injury.

Try this instead: Add rotational movements that involve your entire body. I like performing these moves with dumbbells or with the cable machine. Typically these moves are best done first with lighter weights and really focus on form. Your low back will thank you.

Leg Extension Machine – Sure, this machine gets your muscles fired-up pretty quick (and it was even prescribed to me during a physical therapy session that I went to), but I think this machine is worth ignoring. The way this machine is designed, it places the load (the pad on your shin) so far away from the hinge (your knee), which puts a large amount of stress on the knee joint. It’s also not very easy or impossible to adjust the seat enough, so if you have short legs (like I do), it places the load in the wrong place. This type of machine puts more stress on the body because the weight is being dispersed onto a localized area, rather than using supporting muscles to help distribute the load. All of this to say that this machine increases your risk of developing knee pain or other injuries.

Try this instead: Focus on movements that engage multiple muscle groups, like the Bulgarian split-squat and front squat. If you’re looking for an added bonus, try holding a single-leg squat stance for as long as possible at the end of your workout. This type of isometric exercise will help you see results much faster than any time spent on the leg extension machine.

Ab Wheels – The chase for six-pack abs has made these little wheels pretty popular. But I think there are much more effective ways to increasing your core strength that doesn’t come with such a high risk for injury. Not only does the ab wheel not take you through a full range of motion, it’s a very difficult motion to execute properly. It’s not a functional movement and it takes a lot of core strength, so most individuals cannot perform this exercise without putting unnecessary strain on the low back.

Try this instead: Perform exercise movements that emphasize core strength and stabilization, like planks. Also, keep in mind that when you lift weights, you typically are engaging your core muscles.

With any exercise or machine, it’s important to start slowly. Machines certainly have their place in nearly any workout routine, but not all machines are worth the time.  With their sometimes-questionable benefits and potential for injury, some machines are better left alone.