Slideshow: 7 Risky Exercises and Better Bets

Who has time to waste on ineffective, risky exercises? Not you. So ditch these seven moves that won't deliver the results you want -- and may even cause injury.

The problem: Only people with very mobile shoulder joints can keep their spines straight enough to do this exercise properly. And if the bar hits the back of the neck, it could injure cervical vertebrae.

On the pull–down machine, lean back a few degrees, use a wider–than–shoulder grip, and bring the bar down in front of your body to the breastbone, pulling shoulder blades down and together. Contract your abdominals to stabilize the body, and avoid using momentum to swing the bar up and down. The lat pull–down works both lower and upper back muscles.

This shoulder move, in which you lift a barbell up and down behind the head, can cause the same problems as the lat pull–down behind the head.

A safer shoulder alternative: When doing the military press, keep the bar in front of your head. Stand with the weight no lower than the collarbone and keep your upper body upright. The exercise can also be done seated. Always sit straight against a back support, and keep the natural curve in your spine, with upper back and glutes pressed to the chair.

The problem: Pulling weights, a barbell, or a weighted cabled bar up under your chin can compress the nerves in the shoulder area.

Instead of doing an upright row, work your shoulders with a front or lateral shoulder raise, lifting weights out to the front or side of the body. Keep a slight bend in your arms.

From a reclining position, you push the plate up and bring it down in this common exercise to work the quadriceps, hamstrings, and glutes. The greater the motion, the more joints are worked through full range, which is good. However, if there is pain at any point during the motion, do not go any further.

If you want to do a lying leg press, keep your butt from rotating off the back of the machine. Push from the knees as far as you can, but if you experience pain, do not stretch as far. The greater the motion, the more the joints are worked.

The problem: The bar on the machine doesn't give, which can force the body into risky positions. Plus, people tend to put their feet farther in front of their bodies when doing squats on the machine, which makes matters worse.

It's not necessary to use weights when doing a squat, but if you keep good form, adding weight will intensify the move. Standing straight with your feet shoulder-width apart, slowly lower your body, back straight. Move the hips back as if you are going to sit in a chair. Try to maintain your weight directly over your heels. Slowly return to a standing position.

The problem: Hunching over or using a death-grip on the handrail cheats your body and can throw off your alignment, jarring your spine, shoulders, and elbows.

Don't set the incline or resistance so high that it causes you to hang on to the machine too tightly. Use a natural gait with a light grip. For a more challenging workout, hold on lightly with one hand and move the other arm, switching arms periodically. Walking on a treadmill without holding on also helps strengthen your core. And save the reading for after your workout so you can focus on good form.

People who do strengthening and toning exercises in an effort to trim fat from a certain area -- thighs, hips, stomach, or arms -- have the wrong idea. Although these exercises can help firm muscles, if the targeted area still carries an extra layer of fat, it won't look much different. You can't isolate fat loss to one part of the body.

Cardiovascular exercise will torch calories, but resistance training is a big part of the equation if you want to burn fat. Boosting your muscle mass increases your metabolism, so you burn more calories all the time, even when you're not working out.

Even if you're doing everything else right, your efforts can be undermined by improper footwear. Working out with the wrong shoes increases pounding on the joints, and can lead to injuries like plantar fasciitis or tendonitis.

The key, experts say, is to choose a shoe that is specific to your activity and that suits your particular foot. They recommend shopping at stores specializing in athletic shoes, where you can seek advice from a knowledgeable salesperson. And don't forget to replace your shoes when they show signs of wear.