One of a trainer's biggest pet peeves, aside from rude gymgoers, is watching people perform exercises incorrectly. It really gets to us. Sometimes we're annoyed by total disregard for form in the name of lifting heavier weights; often we're just concerned about your safety. But many of us aren't comfortable approaching you on the gym floor to let you know your form needs work. We don't want you to think that we're superior know-it-alls or, worse, that we're trying to sell you something. Likewise, we know you're not always comfortable asking us for help.
So, on behalf of my fellow trainers, for your sake and for our sanity, I'd like to offer my list of the top five exercises I see done incorrectly and suggestions for ways to improve your form.
Exercise #1: Lat Pull Downs. You know this one, with the wide bar hanging from a cable where you sit on the seat and pull it down in front of you. It works your latissimus dorsi ("lats"), a large muscle on either side of your mid-back. What You're Doing Wrong: There are several rather offensive versions of this one I've witnessed: jerking the bar down and letting it pull your body weight off the seat on the way up, rounding your shoulders forward and pulling it to your stomach, and the biggest no-no, pulling it behind your neck instead of in front of you. How to Fix It: Lean back slightly, keeping your chest lifted, and bring the bar no lower than the top of your chest. Your elbows should end up tight to your sides with your forearms vertical and hands pointing up, so that your arms form a "W." Squeeze your shoulder blades down and together at the bottom of the movement, and then slowly let the bar back up without lifting your shoulder blades or shrugging your shoulders.
Exercise #2: Romanian Dead Lifts. They sound exotic, but you've likely seen someone doing them, or you might do them yourself. These involve holding a bar or dumbbells in front of you and bending forward from the hips with legs straight as if you're trying to touch your toes, then standing back up. They work your low back, glutes, and hamstrings. What You're Doing Wrong: The most common offense here is leaning forward with a rounded back instead of controlling the movement with the legs. How to Fix It: Start with your chest lifted, back slightly arched, legs straight (but don't lock knees), and weight shifted back onto your heels. Keeping your abs in tight and your back nice and straight, start pushing your hips back and slide the weight down the front of your legs until you feel a stretch in your hamstrings. It should take you about 3 seconds to get down. (Do not round your back to get down lower.) At this point your body should be forming an inverted triangle from the side view. Squeeze your butt and stand up a little more quickly than you came down by pushing your hips forward until you're standing up straight.
Exercise #3: Bicep Curls. Seemingly the simplest of strength-training moves, this is probably the one I see done wrong most often. What You're Doing Wrong: Going too fast, using momentum ("swinging" the weights), and using your torso to get the weight up are most common. How to Fix It: First, hold still. If you're moving your body, you're cheating. Instead, pull in your ab muscles to keep your core in place. Second, slow down and control the movement. It should take a couple of seconds each way to get the weight up and down. No swinging allowed. Finally, keep your upper arms glued to your sides at all times. If this part of your arm is moving, then your shoulder joint is moving, which means that your shoulder muscles are helping the movement. This is an isolation move, so biceps only.
Exercise #4: Tricep Pushdowns. This is another basic arm-strengthening move frequently gone haywire. It involves attaching a rope or bar to an overhead pulley, standing under it, and extending your arms downward to work your triceps. What You're Doing Wrong: I often see people moving their entire arms up and down in front of them and letting the cable jerk their arms back up following the extension. How to Fix It: To do this isolation move correctly, you have to squeeze your upper arms against your sides and keep them still. If you're moving your shoulder joint at all, you're not isolating your triceps. The only thing that should be moving is your elbow joint, which will straighten as you use your triceps to press the weight down. Then, on the way up, go slowly and control the movement, allowing a few seconds for your elbow to bend back to 90 degrees. Make sure not to round your shoulders forward, which will cause your traps, or shoulder-shrugging muscles, to get involved.
Exercise #5: Crunches. Ah, crunches. Everyone knows them, and yet so few of us do them correctly. The following rules of form apply whether you're doing them on the floor or over a ball. What You're Doing Wrong: The most common mistakes are bringing your elbows up (and thus pulling forward on your head and neck) and rapidly jerking off the floor with the back muscles. How to Fix It: Keep your elbows wide and your chin pulled in slightly, and look straight up at the ceiling. If your head and elbows move forward, you're not using your abs---you're using your neck. Slowly curl your spine like a "C" and lift your shoulder blades off the floor, exhaling as you lift. Pause at the top, and then inhale and lower slowly. Your low back should maintain contact with the floor or ball at all times. If you can't perform this movement without jerking, your low back muscles may be too tight to allow for adequate spinal flexion. Try placing your legs over a chair or stability ball so that your hips and knees are bent to 90 degrees to improve range of motion.