One Arm Biceps Curl
A single-arm machine curl: with your upper arm resting on the pad and your elbow at the pivot, you curl one handle toward your shoulder, isolating the biceps on one side.
- Primary muscles
- Biceps
- Difficulty
- Beginner
- Logged as
- Weight × reps
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Why do it
It suits anyone who wants machine-strict curls and also wants to see whether one arm is stronger than the other. Working one side at a time means your stronger arm can't carry the weaker one, and the pad keeps your upper arm still so the biceps does all the work. Compared with a two-arm machine curl, sets take longer, so it's most useful when evening out a difference between sides matters more than quick volume.
How to do it
Set the seat so your working arm rests flat on the pad with your elbow at the machine's pivot.
Sit upright with your feet flat and grip the handle with your palm facing up.
Curl the handle toward your shoulder, keeping your upper arm on the pad.
Lower it slowly to full extension, then finish all reps before switching arms. One arm at a time makes a strength difference between sides obvious.
Common mistakes
Elbow not lined up with the pivot
If your elbow sits off the machine's axis, the handle path fights your arm and the rep feels jerky. Adjust the seat until your elbow and the pivot line up.
Lifting your upper arm off the pad
Raising your arm to finish the curl lets your shoulder help. Keep your upper arm flat on the pad from start to finish.
Leaning into the working side
Twisting your torso toward the handle adds momentum. Sit upright and keep your free hand resting on your thigh.
Starting with your stronger arm
If the strong side goes first, it sets a rep target the weaker side can't match. Start with the weaker arm and match those reps on the other side.
Sets, reps and progression
How many sets you do and how close to failure you take them depend on your goal and your week, not on the exercise. These guides cover it:
Alternatives that train the same thing
Same movement, a different angle or piece of equipment.
