To perform both exercises with proper, effective form, the key is to ensure all movement originates from the elbow joint. Brace your core, pin your shoulders back, and don't let your torso or hips move even the slightest to help propel the weights up and down. Maintain a strong grip on the dumbbells too, squeezing the handles to make sure that you're getting the most out of every single rep.
Avoid the temptation to make the bottom of each rep a chill position. Keep tension in the front of your arms at all times. It isnt supposed to be easykeep yourself in a constant position of work.
Sklar drops down in weight from the first exercise, alternating biceps curls, to the second, hammer curls. This allows him to focus on strength during the alternating curls (thats just 5 reps per side) while zoning in on volume and endurance with the hammer curls.
Also, its important to remember that the mechanics of each curl variation comes with its own benefits. The traditional curl, performed with a supinated (palms-up) grip, targets the biceps brachii. Thats because the biceps function not only to flex the elbow, but also to supinate the forearm (i.e. get you in that palms-up position).
The hammer curl puts the onus on the brachialis muscle , a key mover of elbow flexion. While its deeper in your arm than the biceps, meaning you cant exactly see it, growing the brachialis widens the upper arm and helps your biceps pop.
Try 3 rounds of this superset at the end of an upper body session or as a standalone routine on days you're chasing a quick pump.