Hollow body hold: the plank's job, face up

A hollow body hold is a hold on your back. You press your lower back into the floor, lift your shoulders, arms and straight legs a few inches, and hold the shallow curve your body makes. In a gym, it does the plank's job face up: the front of your trunk works to stop your lower back arching.

This page covers the setup, the progressions from the easiest version to the full hold, what the studies of similar holds found, how it compares with a plank, the faults, and the sets.

How to do a hollow body hold

1. Lie on your back, knees bent and feet on the floor.
2. Press your lower back into the floor. Tuck your hips under slightly, as if pulling your belt buckle toward your ribs, until there's no gap under your lower back.
3. Lift your head and shoulders a few inches, chin slightly tucked, eyes toward your toes.
4. Straighten your legs and lift them a few inches off the floor, legs together and toes pointed.
5. Reach your arms past your head, biceps beside your ears.
6. Hold, breathing in short breaths behind the brace, and stop when your lower back starts to lift off the floor.

The rule that makes it work: the lower back stays down. If it lifts, the hold has become something else, so make the version easier rather than holding on.

Hollow body hold progression

Each step makes a longer lever, so your midsection has more to hold. Move on when you can keep your lower back down for about 30 seconds.

1. Tuck hollow. Knees bent up over your hips, shins level with the floor, arms reaching toward your feet, shoulders off the floor.
2. One leg out. As the tuck, with one leg straight and low. Switch legs between holds.
3. Legs straight, arms by your sides. Both legs straight and a few inches up, hands reaching toward your feet.
4. Full hollow. Legs straight and low, arms past your head.
5. Hollow rocks. From the full hold, rock gently from shoulders to hips without letting the shape change.

Within any step, raising the legs higher makes it easier and lowering them makes it harder. Find the height where your lower back stays down, and lower from there over the weeks.

What the studies of similar holds found

No study of the hollow body hold by that name turned up in a PubMed search for this page. Studies of exercises that share its two parts, straight legs held low and the pelvis tucked under, give a picture:

• The tuck matters. In 16 men holding both straight legs about 5 centimetres above a board, activity in the upper and lower front abs was higher with the pelvis tilted back, tucked under, than tilted forward. Neutral and tucked weren't significantly different, and the external obliques and the hip flexor measured showed no significant differences between positions.¹
• Long legs beat a curl. In 15 men who held the same tucked pelvic position throughout, lowering both straight legs worked the abs harder than a held bent-knee curl.²
• The plank shows the same two levers. In 19 people, a long-lever plank raised activity in the abs over a standard plank, a plank with the pelvis tucked under raised it in the obliques, and the two together raised both; the long lever did more of the work.³

Read together: the hollow hold combines a long lever with a tucked pelvis, the two things these studies found made a hold harder for the abs. All three measured muscle activity during a single session, not changes over weeks, and the first two only in men.

Hollow body hold vs plank

No study compared the two directly. The closest is a comparison of the plank with the v-sit, a seated hold that, like the hollow, keeps the trunk curled forward. In 30 adults, 15 men and 15 women, the two holds produced no significant differences in the front abs, the obliques or the lower-back muscles; the plank worked the lats and the upper back muscles more. In a second group of 20 adults, the lower back was about 28 degrees more rounded in the v-sit, and the authors put the weak link between people's times on the two tests down to those differences in position and shoulder demand.⁴

So a curled-forward hold like the v-sit and a plank seem to work the abs in a similar range, and holding times on one only weakly predict the other. Use both: the plank in the core workout's "stop the arch" slot on some days, the hollow on others. If wrists or shoulders make the plank awkward, the hollow is the version on your back.

The common faults, and a fix for each

• Lower back lifting off the floor. The main one. Bend your knees, raise your legs, or bring your arms down to your sides until it stays down.
• Legs too low, too soon. Lower the legs only as far as your back allows; higher is not cheating, it's the right level.
• Neck doing the work. Keep your chin slightly tucked and lift from your shoulders. If your neck tires first, rest your head between holds.
• Holding your breath. Short breaths behind the brace.
• Shaking it out past your form. A few seconds of trembling is normal; a lifting lower back means the hold is over.
• Holding through something that hurts. Effort is fine; a sharp or lasting hurt isn't. Stop, and see a doctor or a physical therapist.

How long to hold, and where it goes

• Three holds of 15 to 30 seconds in good position, with 30 to 60 seconds of rest, at the end of a session.
• Harder, not longer. Once 30 seconds is easy, move to the next progression rather than chasing a minute, the same idea the plank page uses.
• In the core block, in place of the plank on alternate sessions, or next to a turning exercise like the Russian twist.
• Write down the version and the seconds, so you know which step you're on. (Progressive overload covers the options.)

If you'd rather not plan it alone

The hollow hold takes a minute; deciding where core work goes in a week that already holds squats, presses and rows is the part a page can't do. Coaching is the version where your workouts are built around the days you actually have, and a weekly call looks at the week you just had and rebuilds the next one. Coaching to build muscle explains how that works, and here's how to apply. Otherwise: end your next session with three tuck hollow holds, each one stopped the moment your lower back lifts.