At first glance, it was hard to tell what the older guy in my gym was trying to do. His lower body was positioned for the curlup, one of the “big three” core-training exercises popularized by Stuart McGill, Ph.D., a professor of spine biomechanics at the University of Waterloo, Ontario. One leg was straight and flat on the ground, while the other knee was bent.
But he held his hands behind his head, like a traditional crunch, and used them to pull his head, neck, and shoulders up off the floor. He ended up with the worst of both worlds: none of the ab-strengthening benefits of McGill’s exercise, with all of the neck-straining disadvantages of the crunch.
The guy seemed friendly enough, and when I struck up a conversation he told me a trainer had shown him the exercise at some point in the semi-distant past. He wasn’t surprised to learn he was no longer doing it correctly.
So I gave him a few tips, he thanked me, and I would’ve forgotten all about it if I hadn’t received my copy of McGill’s new book, Back Mechanic, a few days later. That’s when I realized my own form was in need of a tuneup.
The basic idea behind the curlup is to create tension by first bracing your abs, and then lifting your head and shoulders off the floor. The biggest misconception is that you need to curl your torso up to create that tension.
“There is actually more load change on the abdominal muscles if you only lift the head and shoulders one inch,” McGill says. To get it right, imagine that the floor beneath your head and shoulders is a bathroom scale. Your goal, McGill says, is to “make it weigh zero.”
If you’re bracing your abs correctly—that is, creating mild tension, as if you’re anticipating a punch to the stomach—that tiny range of motion will feel harder than any traditional crunch.
But here’s the part I wasn’t prepared for:
McGill now recommends holding each curlup for a count of 10, relaxing, and repeating six times. That’s your first set, which should last about a minute, depending on how fast you count to 10. Rest 20 seconds, do a second set with four holds, rest, and finish with two holds.
I had always done the curlup like any other exercise. This was the first time I’d seen it advocated as an isometric hold for longer than a few seconds.
This new wrinkle was tested in a 2015 study in the Journal of Strength and Conditioning Research. In that one, McGill and his coauthor compared two core-training programs, using two different groups of subjects—beginners who were unfamiliar with the exercises, and highly trained martial artists.
Both groups developed better core stiffness doing the protocol that included 10-second holds, compared to one in which they did conventional sets and reps.
These were complex programs, with what appears to be about 20 minutes’ worth of core training done four times a week for six weeks. But the key point is one that applies to any core exercise: More time under tension is better than less.
“The 10-second hold is a way to build endurance without getting tired,” McGill says, which is especially important if you’ve struggled with back pain. Fatiguing your core muscles might trigger the discomfort you’re trying to alleviate.
To my surprise, though, when I held each curlup for 10 seconds, I stopped feeling it in my abs and starting feeling it in my neck.
During a curlup, the weight of your head is supported by your neck flexors, the muscles that pull your head forward. The problem, McGill explains, is that some of the neck flexors connect to the jaw, rather than the skull.
If you’re unable to activate those muscles, the load is picked up by your sternocleidomastoid, a muscle that starts on your collarbone and attaches to the skull behind your ear. You’re shifting all the work to the sides of your neck and cutting out everything in between.
McGill says this is a problem he sometimes sees in people who chew a lot of gum. By repeatedly activating their chewing muscles, they relax some of the other muscles that attach to the jaw, including the neck flexors.
Fortunately, there’s an easy way to get those muscles back in the game:
1. Stand up with your neck straight.
2. Place your fists under your chin.
3. Set your tongue on the roof of your mouth, right behind your teeth, and push up with it as you stiffen your neck muscles.
4. Now push up with your fists as you resist with your neck muscles, resulting in no net movement in either direction. There’s no need to go beast mode; a little upward pressure goes a long way.
Once the neck muscles are doing their job, you should be able to feel every rep in your abs, with no neck strain. McGill recommends doing the curlup every day, along with the bird dog and side bridge. (See how to put them all together into one routine in The Fit Man’s Back-Saving Workout.)
Together these three exercises develop endurance in all the muscles that stabilize your lower back, thus helping you avoid pain in your back as well as your neck. No matter how much gum you chew.