Cavaliere spent an entire video to lay out why, even if you have a visible six-pack, you may actually have weak abs. "It's not about what your abs look like from the outside in," he says. "It's how they inherently function and what their strength is from the inside out that matters the most."
Red Flag 1: Hip Flexor Fatigue
If you’re doing ab exercises—say, ab scissors, laying on your back and crossing your legs over one another—and you feel fatigue in your legs and hip flexors, that means you’re working the wrong muscles. Your legs are driving the movement instead of your abs—so you need to fix your form. Cavaliere says that to fix a movement like ab scissors, curl your shoulders off the ground, engaging the abs and making your hip flexors work as assistance muscles rather than the primary target of the exercise. That’ll help build a stronger set of abs in the long run.
Red Flag 2: Lower Back Pain
To be clear, you should not get back pain from ab workouts. Cavaliere points to situps as a key example: If your lower back starts to hurt with as you perform reps, it’s again because your hip flexors are doing the work instead of your abs, which in turn puts stress on your lower back.
If you need to anchor your feet, if your shoulders trail when do the movement, and if you slam your back down to the floor after each rep, you have weak abs. Fixing your form will again get this exercise focused on the right muscle group. Cavaliere suggests changing your anchor point to pull back against something to engage your hamstrings instead, since you'll end up taking your lower back out of the equation.
Red Flag 3: The “Big 3” Boost
Abs don’t just work when you’re targeting them. They’re also helping provide stability in other exercises, particularly, the "Big 3" lifts you probably build your routine around: bench presses, squats, and deadlifts.
Cavaliere points out that if you're consciously bracing for these exercises—instead of just doing the moves, and allowing your core to lend support—and you feel you could probably add more weight, it probably means your abs are weak and need attention.
Red Flag 4: Bloated Lower Abs
If looking in a mirror reveals bloated lower abs, that means you’re not strong enough to contract the https://www.menshealth.com.au/transervus-abdominis-workout muscle (which runs horizontally around the waist, like a weight belt). It’s a key muscle, and using proper form when it's engaged by contracting it during ab workouts will make sure you’re targeting it.
Red Flag 5: Instability in 3 Planes
Can you get off the floor without using your hands or elbows? That’s a basic test of ab strength.
Cavaliere runs through three more measures, each testing a different plane of motion (sagittal, frontal, and transverse). The tests demonstrate how strong abs stabilize the body in each of them. If you fail at any of the tests, your abs are weak—and you’ve got some training to do.
This article originally appeared on Men's Health