Lie face up on bench. Place feet flat on floor to maintain lower back in a flat or neutral position (slight arch). Keep arms vertical and dumbbells directly over chest with wrists straight. Keep shoulder blades squeezed together (retracted) and maintain position throughout entire exercise. Throughout motion, shoulders form a 90 degree angle to body. In a controlled motion, start lowering dumbbells in a triangular manner until upper arms are approximately parallel to floor. Dumbbells must remain over elbows. While maintaining the controlled motion, push dumbbells up to starting position without locking out elbows. Do not allow muscles to relax before next repetition.