Lie face-down on the floor with your arms extended overhead. Squeeze your back and glutes to lift your chest, arms, and legs off the floor at the same time, creating one long line from your fingertips to your toes. You should feel your entire posterior chain firing. Keep your neck neutral — look down slightly rather than craning your head up. Breathe steadily and hold the position. If your lower back pinches, ease off the intensity; the goal is an isometric hold, not a max-effort squeeze.