For this movement, you shouldn't settle for anything other than perfect formespecially because it's such a killer exercise for a key muscle. Let Men's Health fitness director Ebenezer Samuel, C.S.C.S. and associate fitness editor Brett Williams guide you through the move's subtleties, saving you from the bad habits that are keeping you from unlocking your fitness potential.
Before you grab a dumbbells, set up on the bench or preacher curl station, and get pumping on those reps, take note that it's extremely important to pay attention the movement here. Using the proper form is essential to make sure you're getting the most out of the exerciseparticularly because of how common it is for guys to get lazy with the position, especially in regard to maintaining constant tension through the movement. Let's break down everything you need to know.
Armpit Hugs The Bench
Eb says: There should be zero space between your underarm area and the bench. Close the space and make it tight. This will prevent you from leveraging and it will also insure that you're using a consistent upper arm angle throughout the curl. It insures that your upper arm mirrors the angle of the bench, and that's what we need here.
Upper Arm Glued to Bench
Eb says: One of the most common errors in the preacher curl, especially as you start to try pushing more weight, is the elbow rising off the preacher bench. Glue your upper arm to the bench, from elbow through armpit. Keep. It. There.
Once the elbow is rising off the bench, you're no longer focusing the curl on the biceps; instead, your front deltoid is trying to drive the motion. That's taking tension off your biceps, and it's also compromising your front shoulder, which simply can't handle as much load as the larger biceps muscle. Don't let this happen.
Sit Low
Eb says: It's tempting during preacher curls to use body English to drive the dumbbell upwards. When the biceps gets tired, you start to rock backwards and essentially sit your torso lower, trying to use your shoulder as a fulcrum and drive the weight up. Head this off before you even start a sit.
After you've hit our other key setup points, sit down low, engaging your glutes, hamstrings, and abs. Not only does that help make the preacher curl (which is an isolation move) a full-body exercise, but by starting low and creating that engagement, you can't involve those muscles more when the set wears on; they're already involved.
Slow Tempo
Eb says: Don't rush preacher curls. This isn't an explosive curl. It's a smooth, constant-tension motion. Feel the stretch at the bottom on each rep; linger there. Then work to feel your biceps "drawing" your forearm upwards, using a patient, controlled contraction instead of a hyper-explosive one.