Your Spine Hyperextends
If your spine hyperextends then your core isn’t strong enough for standard pushups.
The goal in a push up is to maintain a rigid body with an imaginary line from your head to your toes, says Miriam Alicea, NASM CPT, NASM CES and MYXfitness coach.
“When the spine collapses or hyperextends, it’s usually not a result of upper body strength,” she says. “Instead, it’s usually due to insufficient core strength and the ability to stabilize the lumbopelvic region and keep it neutral throughout the motion.”
Tight hip flexors can also pull your hips into anterior pelvic tilt, which therefore makes proper glute training and engagement a key player in good push-up form, she says.
Fix it: When doing push-ups, cue yourself with “tuck the tailbone” and “close the rib cage.” These cues should remind you of proper alignment, Alicea says. If these cues don’t work, lengthening the hip flexors, along with strengthening the core and glute muscles, will help you establish proper core control and avoid hyperextension during push-ups.
Try core-strengthening exercises such as planks, bird dogs, dead bugs and hollow body holds; glute-strengthening exercises such as single-leg deadlifts, hip thrusts and good mornings.