Begin in a plank position. shoulders stacked over the elbow, legs together and extended behind you. Assume a posterior pelvic tilt (tuck tailbone), brace your core and squeeze your glute. Create global tension.
Drive your elbows into the floor, exhale and protract your scapula (spread your shoulder blades apart) pausing at the top. Now lower yourself into scapula retraction (shoulder blades together).
Repeat for repetitions, maintaining total body tension, and not allowing your back to arch.