We love the plank. “It teaches intervertebral stability, which can stabilize the spine at the top of a kettlebell swing, squat or deadlift,” says Mike Fantigrassi, NASM-CPT and Master Instructor. But to get the full perks from planks, it’s important to focus on form and posture, not on a lengthy hold time.

“Planks should be held only as long as perfect position can be maintained,” says Fantigrassi. “Start with a maximum contraction of 3–10 seconds and work up to 20 reps,” he advises. If you think clients will find that surprising, look at these other ways to perfect and progress the plank:

Start high and finish low. Elevated or “high” planks won’t cause the butt to pike in the way that knee planks can. Begin with hands on a bench or Smith machine bar, which can be lowered a little at a time. Once clients can hold this high plank in perfect form for 30–60 seconds (or for 12 reps at 5 seconds each), they’re ready to progress to the floor, then to forearms.

Check the kinetic chain. With feet shoulder-width apart and toes under heels, align heels, knees, hips, shoulders and head in a straight line, keeping back in neutral, shoulders down and back, arms shoulder-width apart, elbows under shoulders and eyes on floor. “Keep the hands apart,” reiterates Fantigrassi. It breaks up the position used for long periods of driving or typing.

Squeeze out more benefits. To keep the body in alignment, draw in, brace and engage the glutes. Too easy? Squeeze the quads, too. Want more? Dorsiflex the toes and pull the elbows toward the toes (without moving), or move the elbows forward beyond the shoulders.

Challenge their balance. Lifting a hand or foot (or one of each) can add a layer of difficulty. However, it can also throw off proper alignment. Keep these moves minimal: Cue clients to simply point one toe and/or (in pushup position) lift one palm slightly.

Watch for form breakdown. Call for a reset when you see the back, hips or head sag (or pike) or the shoulders shrug. Also, cue a rest break when you can see that muscles are not contracted, which means the ligaments and bones have taken over the job of supporting the body.

Source: https://magazine.nasm.org/american-fitness-magazine/issues/american-fitness-magazine-winter-2018/training-edge