Spider Curls are used to isolate the bicep and shape the peak of the bicep.
Begin by placing an EZ Curl Bar on the seat of a preacher curl bench. Then, go around to the other side and stand facing the preacher bench. Remain standing, but lean your torso onto the preacher bench; this is usually where your arms are during a standard preacher curl. Next, place your upper arms on the preacher curl bench; your arms will be leaning on the pad that your chest is usually pressing against. Reach down and pick up the bar with your palms facing up. Slowly curl the weight and bring your forearm to your shoulder; continue this movement as far as you can go. Squeeze your biceps at the top and then slowly lower the barbell back to the starting position. Repeat this movement until you have completed your set.
You can use dumbbells for this exercise, but it would be safer to have someone hand you the dumbbells.
Be careful when you place the barbell on the seat of the preacher bench; make sure it is balanced so it will not fall over.