Behold the plank —  an exercise that could almost be considered enchanted.

Seriously, have you ever wondered how an an exercise that involves NOT moving could be so challenging? Or how not moving could make all sorts of muscles stronger for when you ARE moving?

Get a load of this list of muscles planks (or hovers) strengthen:

• Primary muscle groups: erector spinae (the muscles along your spine), rectus abdominus (the front of your abs — the “six-pack” muscles) and the transverse abdominus (the deeper ab muscles).
• Secondary muscle groups strengthened include your trapezius, back, shoulders, obliques, chest, glutes, thighs and even your calves.

That’s a LOT of muscles!

Because they involve so many muscles working in concert, planks are deceptively tough. And because all those body parts have to align to hit the form, planks tend to highlight any muscles imbalances you might have brewing, whether it’s tightness through your hips and chest, or inactive/weak groups like your upper back or glutes, and more.

Below, I’ve added a cheat sheet to help you perfect your plank form. But first, here are some illustrations of well-intentioned planks, and then one with performed with great rockstar technique. Do these plank issues look familiar? (Many thanks to my model Holly Nickerson, a BodyAttack instructor at my gym.)

1. The teepee plank

This is probably the most common plank faux pas. It’s called the teepee because we lift up our hips to form a teepee shape. We tend to do this when we’re tired and/or don’t have the core strength to support our spine in neutral alignment.

Why it’s not helpful: lifting your hips takes much of the work out of your core muscles, places a lot of load on your low back and can be tough on your shoulders. A quick way to tell if you’re doing this is to check if your head is dipping toward the floor.

How to fix: Drop your knees to the floor and reset so that your elbows are directly under your shoulders, neck long. Then lift your knees and press your weight into your heels. If doing this is too challenging, do the plank from your knees.

2. Saggy Plank

This is another common plank issue that often happens when we are trying to avoid the teepee plank. We overcorrect and let our stomach sag, creating a sway back.

Telltale signs: the legs are slightly relaxed here, stomach is dipping, and the chin is up. Plus, just looking at that arched back kind of makes your own back hurt, doesn’t it?

How to fix: Squeeze through the quads, pull ribs toward the spine, press into the arms and tuck the chin.

3. Rockstar plank

This is a plank with great form — her neck is in neutral alignment, shoulders down and back, rib cage long, hips are at shoulder height and she is engaging her thigh muscles.

Ready to build your perfect plank? Have a mirror nearby so you can check out your form — without visual confirmation it’s hard to know whether or not you’re nailing it. And if you can’t hold the form from your toes, you always can do the plank from your knees until you build the strength to do it with straight legs.

Perfect Plank Checklist

First, build a foundation.

• Set up so that you’re lying on your stomach, your elbows directly under your shoulders.
• Knees should be just slightly wider than hip width.
• Lift up on your toes, so that your hips rise to shoulder height.
• Brace your abs (draw your ribs in slightly toward your spine), keeping your back long and straight.
• Shoulders are back and down (avoid hunching or sagging through your shoulder blades — think STRONG).
• Eye gaze is toward your fists so that your neck stays long.

That’s the foundation. Next, to refine it.

• Think about squeezing your quads (the big muscles in the front of your thighs) by lifting your kneecaps slightly.
• Press into your heels, making your legs long, as if they are steel rods supporting you.
• Push against the floor with your forearms and open the chest slightly.

Start by holding for 30 seconds, and build up to two minutes.

Are planks in your regular core/ab routine? Let me know! If you found this helpful, I’d love it if you would share with a friend.