When you perform exercises for a long time, you might forget about the rules and important details that make them effective. That’s how you end up with exercises you’re doing wrong, and that means that your muscles are getting less of a workout.

From planks and lunges to exercising with a jump rope or stair machine, here are a few common mistakes that are preventing you from getting the best workout and might even be causing harm. Take the time to analyze your exercise routine temporarily and make sure that you’re not doing it wrong.

Planks

If you look forward to planks because they seem an easy exercise, you might be doing them wrong. If you can stay in the position for more than 20 seconds, you’re definitely not engaging your core muscles, and you’re relying too much on your joints. Your elbows should be aligned with your shoulders and the line of your body should be completely straight.

Leg Lifts

Side Leg Lifts

The classic side leg lift can help you tone your legs, but it’s one of the exercises you’re doing wrong if you’re performing it on a flat surface. By lying flat when you do side leg lifts you’re working out your hip muscles more than your legs. Try this exercise with your elbow on a low platform and your bottom leg bent at the knee for a better workout.

Lunges

When you do lunges, your knee should never go past your ankle. That puts all the pressure on your front leg knee instead of distributing it to your hips and ankles as well. Try to focus on the stationary position first to make sure that you’re not pushing your front knee too far out.

See also: When It's OK to Skip a Workout

Crunches

They’re not the best way to get great abs, and crunches might also be one of the exercises you’re doing wrong. The most common mistakes include using your arms to pull your head upwards and pushing with your legs. Your elbows should be open wide, and always make sure that you’re actually curling your body over the ribcage, not pushing your belly upward.

Doing Squats

Squats

When you’re doing squats incorrectly, your risk of a knee injury is much higher. If you start them by pushing your knees forward and don’t go low enough, the joints are taking all the pressure and your muscles aren’t involved as much. The trick to doing squats correctly is bending your knees while you’re pushing your hips back, and always making sure that your knees are aligned with your ankles.

Lat Pulldowns

Getting toned arms is important, but lat pulldowns could be one of the exercises you’re doing wrong. If your leaning too far back and your hands are too far apart. In order to do this exercise correctly, keep your arms parallel to your spine and only lean back from the hips up to 15 degrees. Always pull the bar in front of you, slightly below your chin.

Horizontal Running

Biceps Curls

Not nearly as effective when you’re sitting down, biceps curls should always be performed while standing up. That helps work out muscles in your lower back and legs. Whether you’re using dumbbells or a bar, do biceps curls standing up.

More: 10 Fitness Hacks for Beginners

Push Ups

There are plenty of mistakes that could make push ups one of the exercises you’re doing wrong. The most common one is pushing your hips too high, but having your hands too close together or lowering yourself too much and losing the important body alignment. Always keep your neck aligned with your spine and your whole body in a straight line for good push ups.

Jumping Rope

Jump Rope

Even if it seems very simple, jump rope can be one of the exercises you’re doing wrong. The most common mistake is using a rope that’s too short, which means you’ll be hunching to avoid hitting your head. When you’re sitting on the right rope, the handle go up to armpit height. You should use your wrists, not your shoulders, while landing on the balls of your feet, not the full sole.

Stair Climbing

Exercise on the stair climber machine can also get tricky. Supporting your upper body weight on the console is a bad idea, since it reduces the impact of the workout and can negatively affect your posture. If you can’t keep your balance by resting a single finger on each side rail, you might need to slow it down.