The spider curl is a great exercise! Here's how you do it.
Put your chest on the bench pad at about a 40 degree angle. Start with your chest on the bench and your feet on the floor. Be sure to squeeze your shoulder blades, abs, and glutes to create full-body engagement. Hold a dumbbell in each hand with your arms perpendicular to the floor. Then squeeze your biceps to curl the weight up. Pause briefly at the top of the movement, then lower the weight back down under control.
The simplicity and effectiveness of this curl make it one of my go-to exercises for arm training.
Thanks for reading!