There were two lat-pulldown stations positioned next to each other in this gym I belonged to many years ago. On one of them was an older woman who was lifting, if memory serves, 10 pounds. I can only assume that she misread the name of the exercise and thought it was a lap pulldown, because thats where the bar ended up when she rolled it down the front of her torso.

On the adjacent machine was a guy who was lifting, if memory serves, the entire weight stack, or most of it. He rose off the seat at the beginning of each rep to help him get the stack moving, and then leaned back at a 45-degree angle to get the bar to his chest. The deeper he got into his set, the more momentum and body English he employed.

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Two people, two completely different ideas about how to do one of the simplest exercises in the gym. And both of them completely wrong.

If you walked into that same gym today, chances are youd see multiple versions of exercises hardly anyone did a decade ago, like planks and kettlebell swings. Those are in addition to the classic exercises, the simple ones that every lifter has done as long as hes been lifting, but may not be doing in a way that helps him reach his goals.

Theres more free information than ever, and yet form hasnt improved, said Nick Tumminello, author of the upcoming Building Muscle and Performance: A Program for Size, Strength, and Speed, and a trainer based in Fort Lauderdale. Men are stubborn, and they always think they know better.

Flawed exercise form really comes down to three basic problems:

   Lack of control

   Poor stability

   Misunderstanding the point of the exercise

Lets tackle them in that order.

Control issues

Most people are in the gym to do bodybuilding, Tumminello said. That is, to build muscle. But most guys in the gym train like weightlifters, where the goal is to lift the weight. Theres a big difference. Bodybuilding is about controlling the weight through the entire range of motion.

Take the lateral raise, for example. The way most guys do it, Tumminello said, is to swing the weight up, and let it crash down.

But the entire point of the exercise is to target the middle part of the deltoid muscles. To make them grow, you need to put them under tension. Theyre under the most tension at the top of the range of the motionthe part everyone cheats through, he says.

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You see this over and over in exercises designed to target specific muscles, including the lat pulldowns I described at the beginning. Tumminello also mentioned the bent-over barbell row: Theyll pull it halfway with good form, then jolt it the rest of the way.

He offers a simple fix:

Select a weight you can hold at the point of maximum tension, with good form.

If you cant hold it four to five seconds, then the weights too damned heavy, he said. You dont need to hold it when you train, but thats how you should test it.

For most bodybuilding exerciseslateral raises, lat pulldowns, bent-over or seated rowsyou can test your weight at the end of the range of motion. For biceps curls, its the midpoint, when your forearms are parallel to the floor.

Or you can make it simpler, and just remember which part of the lift you typically have to cheat to get through. If you cant hold it there for a few seconds, try using a lighter weight.

Bad posture

Picture these four exercises:

   Plank

   Pushup

   Loaded carry

   Bear crawl

What do they have in common? If you answered, Theyre all the same exercise, youre a lot smarter than me. It never occurred to me until Alwyn Cosgrove, my coauthor on the New Rules of Lifting books, explained it.

Of course they dont look alike. But the key to good form is exactly the same: Whatever your posture is standing up straight, thats what it should be when youre doing a plank, or a moving plank (aka pushup), or a walking plank (aka loaded carry), or a scooting plank (aka bear crawl).

On the plank, pushup, and carry you should be able to draw a straight line from your ears through your shoulders, hips, and heels. On the bear crawl, the line should connect your ears, shoulders, and hips, with your torso parallel to the floor.

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The most common mistakes are postural. With the plank, pushup, and bear crawl, you see these almost every day:

   sticking your butt in the air

   letting your stomach sag toward the floor

   lifting your head to check out the form of the person in front of you

On a pushup, you can tell if youre lifting your butt when your nose reaches the floor ahead of your chest. If your stomach is sagging on a plank or pushup, youll probably feel it as an uncomfortable strain in your lower back. And if you find yourself mesmerized by the person in front of you on any of these exercises, youre probably lifting your head.

The biggest problems on loaded carries come when the weight is held to one side, as in a suitcase carry. Mistakes might include:

   Bending to the side holding the weight

   Overcompensating for the weight by bending to the opposite side

   Leaning back and flaring your rib cage out

You can self-correct the first two issues by paying attention. If youre sober, you should be able to tell if youre standing up straight. If its a struggle, lower the weight.

A good self-check for the latter problem is to place your non-weight-bearing hand on your sternum. If you feel your bottom ribs start to move forward, adjust your posture.

Cognitive failure

Return for a moment to the confused woman at the lat-pulldown station, the one pulling the bar down to her hips. Clearly, she didnt understand that the goal of the exercise is to engage muscles in her middle and upper back, and to do that she needed to select a somewhat challenging weight and pull the bar to her chest.

I remembered it because its not something you see every day.

But there are a few commonly misunderstood exercises youll see on a regular basis. Tumminello mentioned the hanging knee raise. As ab exercises go, its about as hard-core as most of us will ever get. But thats the problem: Most of us cant actually do the exercise correctly.

To do it right, Tumminello said, you need to tilt your pelvis upward, something thats hellaciously difficult from a dead hang. Instead, most guys will just lift their knees, a movement that works the hip-flexor muscles on the front of the pelvis but doesnt work the rectus abdominis, the six-pack muscle, through the intended range of motion.

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If you cant do that pelvic tiltand as I said, few of us canthen youre much better served by doing the reverse crunch from the floor or an incline bench.

Another common mistake involves exercises for the opposite side of the torso. When you do a kettlebell swing, the goal is to move the weight by straightening your hips. That engages the powerful glute and hamstring muscles. Your arms and shoulder are just along for the ride.

But before you can straighten your hips, you have to load them by pushing them backwards. If you dont do that, you cant generate the force necessary to swing the weight out in front of you. Thats why you see so many people turn the swing into a front raise: theyll kind of squat down, and then pull the weight up overhead using their shoulder muscles.

A good swing, by contrast, should end up somewhere between waist and chest height. One way to tell if youre getting it right: the bell goes just a little higher than your hands at the top of the swing. If youre lifting it with your arms and shoulders, itll do the opposite, and end up below your hands. (For a full tutorial on how to do the exercise, check out The Right Way to Do a Kettlebell Swing.)

How to do any exercise better

The lessons of these nine exerciseslateral raise, bent-over row, plank, pushup, bear crawl, loaded carry, lat pulldown, hanging knee raise, kettlebell swingcan be applied to any exercise you try. You just need to ask yourself three questions:

1. What is the point of the exercise?

If the goal is to build muscle, then focus on creating tension in the targeted muscles, and dont use momentum to blow through that part of the exercise.

2. What should my body look like while doing the exercise?

This is trickier, because on many exercises its hard to check your form without breaking form to look at yourself. And thats only if you have a mirror nearby. Without one, you have to pay attention to your bodys signals. If you feel a strain in your lower back on a plank or pushup, thats your cue to work on your alignment.

3. What actions should and shouldnt be involved?

This is even trickier, and may require coaching, or at least some reading outside the gym. Most people looking at a kettlebell swing would think the goal is to lift the weight up in front of you, so it makes sense that youd use your arms and shoulders. If nobody tells you its all in the hips, how would you know?

Which brings me to perhaps the most reliable cue: When other lifters stop, stare, and then shake their heads as they walk away, you can be pretty sure youre doing something wrong.

Lou Schuler is an award-winning journalist and contributing editor to Mens Health. Check out his new book Strong: Nine Workout Programs For Women to Burn Fat, Boost Metabolism, and Build Strength For Life, with coauthor Alwyn Cosgrove.

This article originally appeared on MensHealth.com.