Scapular Push-Up

This one never bends your elbows. Set up in a push-up position, arms straight and locked, then let your shoulder blades sink and squeeze together, dropping your chest slightly between them. From there, push the floor away -- spread your shoulder blades wide and round your upper back, all without your elbows moving at all. The whole rep happens in your shoulder blades, not your arms. Keep your core braced so your hips don't sag or pike; a straight line from shoulders to ankles gives your shoulder blades a stable base to move against. Small, controlled range beats a big sloppy one.