The 5 exercise machines you should never use at the gym

Exercise machines are simple—too simple, in fact. According to metabolic training expert BJ Gaddour, C.S.C.S. owner of StreamFIT.com, "They've been dumbed down to the point that they just don't do your body much good." Besides parking you on your butt, most machines isolate a single muscle, meaning you'll burn fewer calories and gain less muscle mass rep for rep.

Most importantly (at least as far as medical bills are concerned), exercise machines can lead to injury. Even with their adjustable seats and pegs, finding the proper position can be close to impossible—and even then the movements just aren't natural. "Free weights and bodyweight exercises allow your body to move in a natural range of motion," Gaddour says. "When you fix it, it results in a limited and improper movement pattern that can be dangerous."

Here, Gaddour shares five exercise machines you should swear off—and all-star alternatives that will give you better, faster fitness gains.

1. The Machine: Lying Leg Press

Your legs are strong (after all, they carry your body around all day), so if you lie down with your legs above your head for a leg press, you have to load more than the equivalent of your bodyweight onto the machine to achieve significant resistance, Gaddour says. Problem is, all that weight goes straight to your lower back, which flexes under the pressure. The risk? A herniated disk. Plus, the move doesn't even work any of the stabilization muscles in the hips, glutes, shoulders, or lower back. The result: All pain and barely any gain.

Try This Instead: Goblet Squats. Apart from working just about your entire lower body in a single move, this squat variation involves holding a dumbbell or kettlebell in front of your chest to keep your form in check and the weight off of your lower back. Sometimes, a lighter load delivers a better burn.

2. The Machine: Seated Leg Extension

Since the weight is placed so close to your ankles, the machine puts undue torque on the knee joint, which can wear down cartilage and cause knee pain, Gaddour says. Plus, the common gym contraption is built around a motion that has little real-life benefit.

Try This Instead: Step Ups. Besides working your quads far better than any machine, step ups also train your glutes, hamstrings, and calves. By calling up more muscles, your knees are actually strengthened, not worn down.

3. The Machine: Seated Chest Press

While sitting is less than useful, the bigger problem here is that the machine can cause lopsided muscles. How? If one arm is weaker, the stronger one can end up doing all the work—and getting all the benefit, Gaddour says. To make sure both sides of your chest are strengthened equally, you need to load them separately.

Try This Instead: Pushups. An oldie but a goodie, pushups equally engage both sides of your chest. If it didn't, you'd fall right over onto your side. What's more, they tap your core for support and balance. After all, hot bodies aren't built on chests alone.

4. The Machine: Hip Abductor/Adductor

If it looks ridiculous, it probably is, Gaddour says. And squeezing your thighs together—or pushing them apart—over and over definitely counts. Besides actually working very few muscles, it also strains the spine and can make the IT band so tight it pulls your knee cap out of place—not a good look for anybody.

Try This Instead: Single-Leg Squat. When you're not in the gym, your inner and outer thighs largely work to maintain stability. So they should do the same thing when you're in the gym, right? Single leg exercises—like the single-leg bodyweight squat—require those muscles to brace your body and keep you upright, all while putting your quads, glutes, and hamstrings to good use.

RELATED: 5 Reasons to Skip Breakfast

5. The Machine: Loaded Standing Calf Raise

While the idea here is to lift weight with your calves, the machine's setup—specifically the shoulder pads—means that all the weight presses down on your spine before it ever reaches your legs. If it doesn't turn you into a hunchback, it'll at least cause you some back pain.

Try This Instead: Bodyweight Standing Calf Raise. If regular standing calf raises don't have the resistance you need, try standing on one foot during your next set. Besides doubling the weight each calf has to lift at a time, it also puts your legs' smaller, stabilizing muscles to work.

Fox News Health