Sit on the plate-loaded preacher curl machine and adjust the seat so your upper arms rest comfortably on the pad. Grasp the handles with an underhand (palms-up) grip and keep your elbows against the pad. Curl the handles toward your shoulders by flexing your elbows and squeezing your biceps at the top. Slowly lower the weight back to the starting position under control and repeat.
Log your lever preacher curl (plate loaded) sets in 1RM.fit and watch your estimated 1RM update automatically as you get stronger.