Hollow Body Hold

Move · Resistance Training · Movement, Typed Supps

Your hip flexors attach to your lower spine, so straightening your legs actively tries to pull your back off the floor.

Stage by stage

Set-up (Pelvis tilts, spine flattens): Posterior pelvic tilt pressing the lumbar spine to the floor is the entire criterion, and sets the length the abdominal wall must hold.
During the hold (Limb length multiplies torque): Demand scales with how far the arms and legs reach from the centre of mass, so bending the knees is a mechanical regression, not a cop-out.
As fatigue builds (Psoas pulls spine into extension): The hip flexors attach to the lumbar vertebrae, so holding the legs up actively drives the low back into an arch the abs must resist.
Weeks later (Anti-extension endurance builds): Trunk control improves and plausibly helps bracing under load, though direct evidence for transfer to barbell lifting is modest.

Muscles trained

Primary: abs
Secondary: hip flexors, lower back, shoulders

Intensity

3.8 METs (Calisthenics (e.g., push ups, sit ups, pull-ups, lunges), moderate effort).

Time to effect

Weeks: Longer hold times as you learn to keep the lower back pinned to the floor instead of letting it arch as the limbs extend.
Months: Stronger anti-extension core control that carries over to bracing during heavier lifts like squats, deadlifts, and overhead presses.

Common myth

A hollow body hold is basically the same thing as a plank. In reality: A plank mainly resists your hips sagging toward the floor. A hollow hold specifically trains keeping the lumbar spine flattened while the limbs create a long lever pulling against it — a distinct skill gymnasts drill because it underlies nearly every other position in the sport.

In the glossary

Evidence grade