Everyone knows that exercise is good for you. Not only does is keep your body strong, trim, flexible, and with better endurance, exercise improves cardiovascular help, speeds digestion, strengthens the immune system, improves the mood and concentration…the list goes on. Most of us are tempted to think that any exercise will do, however, fitness and sports professionals now know that there is a wrong way to exercise. Some exercises put unnecessary strain on certain parts of the body, waste your time by being ineffective, or are even dangerous. What are the ten worst exercises/techniques, and why are they all wrong for you?

Traditional Sit-Ups and Crunches

Regardless of what they made you do in gym class back in junior high, regular sit-ups and crunches focus solely on the middle abdominal muscle group, called the rectus abdominis, or the muscles of a six-pack. Also, the motions used during sit-ups and crunches can cause back problems, according to studies conducted by Harvard and other universities. Planks are much more effective at strengthening your entire core, without straining the back.

Ab Machine Workouts

Use of ab machines detracts from having a good ab workout, since they allow you to flex your legs, shoulders, and arms, instead of relying on the strength of your abdominal core. Bicycle crunches or crunches on a stability ball make you use more of your core strength.

Lat Pull-Downs and Shoulder Presses Behind the Neck

Anytime you pull down on cables or lift something above your head from behind the neck puts serious stress on the rotator cuff muscles and paves the way to long-term shoulder impingement—a painful, chronic condition. The potential damage to your shoulders increases if you already have limited range of motion in your shoulders. Anytime you plan on lifting weights or want to use a lat pull-down, keep the motion in front of your breastbone.

Leg Extensions

Doing leg extensions on a machine isn’t a functional exercise, because it doesn’t mimic any of the movements a human normally performs during the course of daily life. They’re less effective because they isolate the quadriceps (the front of the thighs), which can result in strained hamstrings if you don’t take care to balance out your leg exercises. Stick to more holistic exercises, like lunges.

Tricep Extensions

Tricep extensions are impractical, because the proper form for this exercise requires that you reach completely behind your back, with the upper arms next to your ears and elbows completely vertical. This often results in neck pain, and if you have a stiff and inflexible back you can’t completely extend the triceps. Tricep push-ups are a more inclusive and more effective exercise.

Ballistic Stretches

Despite what is popularly believed, bouncing into your stretches doesn’t give you a better stretch. In actuality, the muscles contract during sudden overstretching in order to protect themselves. Bouncing and stretching leads to small muscular tears and causes unnecessary soreness. A better way to stretch is to slowly work into a stretch, then hold the stretch for 10-20 second, then rest and hold into a new stretch.

Full Squats

Squats are great upper-leg exercises, but if you force the knee joint to extend past 90 degrees puts you at risk of straining the knee joints and lower back. Keep squats to about 45 degrees and keep an eye to the mechanics of your body by watching yourself in a mirror.

Extended Cardio Sessions

Sometimes, more is not always better, especially when it comes to cardio workouts. Ideally, a jog or another cardio workout should get your heart rate to 65-85% of your maximum. If you stay at that intensity for more than forty-five minutes, you could actually cancel out your strength training regime by burning off muscle mass! Keep your cardio workout to around 3 30-minute sessions per week to avoid this negative, according to the Columbia University Health Services Department.

Waist Twists and Bends

Although you can boost your flexibility a bit by doing waist twists and bends, but it won’t likely pare down your waist measurements or tone your abdominal core. You could actually strain your lower back by twisting and bending down too frequently or abruptly. The safer and more effective torso movement workout for your core is to stand upright, feet firmly planted, holding a weighted medicine ball while rotating slowly side to side.

Any Spot-Reduction Exercise

By doing strengthening and toning exercises for specific areas (such as your glutes or thighs), you do nothing to actually burn fat in those areas. Spot reduction simply doesn’t work. The American Council on Exercise has published on this, giving examples such as how tennis players have around the same amount of fat in their racket arm as in the other. You do, indeed, gain muscle in a specific area by working on it, but it takes cardio to burn fat, and the results of a cardio workout are spread throughout the body.