The cross body hammer curl is an isolation exercise used to train the muscles in your upper arms and forearms.
Compared to regular dumbbell curls, which are done with the palms facing forwards, the cross body curl shifts the emphasis to a different part of the arm.
The biceps brachii is a muscle made up of two heads, the short head and the long head.
If you look down at your biceps, the short head is found on the inside of your arm, near your body. The long head is found on the outside of the arm.
With cross body curls, you’re targeting primarily the long head of the biceps, along with a small muscle found just underneath the biceps, known as brachialis.
You can see what a well developed brachialis looks like in the image below. You’ve got the biceps on top, the triceps on the bottom, with the brachialis sitting between the two.
The cross body hammer curl also works the forearm muscles, specifically a muscle that sits on top of your forearm known as brachioradialis. Like the biceps and brachialis, brachioradialis helps to flex, or bend, the elbow.
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For a complete arm workout, training the biceps and triceps isn’t enough. You also need to focus on brachialis for maximum muscle growth.
Cross Body Hammer Curl: Muscles Worked
- Biceps brachii
- Brachioradialis (forearms)
How to Do Cross Body Hammer Curls: Proper Form
Although you can do cross body curls with two dumbbells, alternating from one side to the other, I prefer to train one arm at a time.
Stand with your feet roughly shoulder width apart and a dumbbell in your right hand, using a neutral grip position (palms facing you). This is your starting position.
Twist your upper body slightly, so your right shoulder comes forward and your left shoulder moves back.
Slowly curl the weight across your body towards the left shoulder.
During each rep, your wrists should remain in a neutral position, as if you were holding a hammer and preparing to hammer a nail into a plank of wood.
Pause briefly at the top, before lowering the dumbbell under control to the initial position.
Don’t worry about keeping the elbow stationary. As you can see in the video above, it’s normal for there to be a small amount of elbow movement as you complete each rep.
The muscles involved in this exercise are relatively small, so you don’t need to use a heavy weight. Instead, focus on proper form, using a full range of motion.
In most cases, you’re better off using relatively light weights, and a smooth, controlled lifting speed. Sets of 8-12 reps, 12-15 reps or even 15-20 reps with a lighter load can all be used to build muscle.
Dumbbell Hammer Curl
With the standard hammer curl, rather than lift your arm across your body as you do with cross body curls, the movement path is straight up and straight down. If your gym has a Swiss bar, the Swiss bar hammer curl is a suitable alternative.
Are cross body hammer curls better than normal hammer curls?
Both exercises are targeting the same muscles – the brachialis, the brachioradialis and biceps.
Brachialis doesn’t cross the shoulder joint, so rotating the shoulder shouldn’t have an impact on the brachialis. It’s much the same story with brachioradialis, which is a single-joint muscle crossing the elbow.
The long head of biceps brachii does cross the shoulder joint, so it’s possible that cross body hammer curls may have an impact on muscle activity in the long head of the biceps.
However, any difference between the two exercises in terms of their ability to stimulate growth in the arms is likely to be extremely small, and you should pick the one that feels like it’s working the target muscles the hardest.
Cable Rope Hammer Curls
As well as dumbbells, you can also do hammer curls with a rope attachment attached to a cable machine.
Reverse-Grip Barbell or EZ Bar Curl
Reverse curls, done with a barbell or EZ curl bar, involve elbow flexion with a pronated grip, which requires even more work from brachioradialis, the muscle that sits on top of your forearm.
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