Single Arm Cable Curl (How To, Benefits, Common Mistakes)

The Single Arm Cable Curl is a unilateral bicep exercise performed using a low cable pulley, training each arm independently through a full range of motion with consistent tension from the bottom of the rep to the top.

The cable maintains load on the bicep throughout the entire range of motion (including at the bottom where a dumbbell provides almost none), making it one of the more complete bicep isolation tools available as an accessory movement.

Primary Muscles Worked: Biceps, Brachialis
Secondary Muscles Worked: Forearms, Anterior Deltoids
Equipment Needed: Cable Machine, Single Handle Attachment

How To Do Single Arm Cable Curls

Step-by-Step Instructions

1. Set-Up:

Set the cable pulley to the lowest position and attach a single handle.
Stand facing the cable stack and grip the handle with one hand using a supinated (underhand) grip.
Take a small step back from the stack so the cable is under tension with the arm fully extended at the starting position.
Stand tall with feet shoulder-width apart, core braced, and the working elbow pinned at the side before beginning.

2. Execution:

Curl the handle upward by flexing the elbow, keeping the upper arm stationary and the elbow pinned at the side throughout.
Curl until the forearm is fully flexed and the bicep is contracted at the top of the rep.
Hold briefly at the top before lowering the handle back to full elbow extension under control.
Complete all reps on one side before switching.

3. Tips for Proper Form:

The elbow stays at the side for the entire set. Letting it drift forward as the handle comes up reduces bicep tension at the top and turns the top of the rep into a front raise rather than a curl.
Control the eccentric. The cable maintains tension all the way back to the starting position. A slow, deliberate lowering phase increases time under tension significantly compared to dropping the weight back down.
Keep the torso upright and still. No leaning back, twisting or rocking.

Key Benefits

Training each arm independently allows direct identification and targeting of side-to-side strength asymmetries that bilateral curl variations mask.
Consistent tension throughout the full range of motion produces a more complete bicep training stimulus than free weight curl variations where tension drops off significantly at the bottom.
Simple to load and progress in small increments. This is particularly useful for isolation movements where small jumps in load make a meaningful difference in rep quality.

Modifications and Variations

Easier Option:

Reduce load and focus on full range of motion and a controlled eccentric before adding resistance.
Stand closer to the stack to reduce cable tension at the bottom if full extension feels uncomfortable at the starting load.

Harder Option:

Add a 2-3 second pause at the top of each rep with the bicep fully contracted to increase time under tension at peak contraction.
Perform a Single Arm Cable Curl Drop Set by reducing the weight immediately after reaching failure and continuing to rep out without rest.
Turn slightly away from the cable stack to increase the stretch on the bicep at the bottom of the rep and train through a slightly greater range of motion.

Common Mistakes

Elbow Drifting Forward at the Top: The elbow must stay pinned at the side throughout the rep. Forward elbow drift at the top reduces bicep tension and shifts the load onto the anterior deltoid.
Not Starting from Full Extension: Shortening the range of motion at the bottom eliminates the loaded stretch that is the primary advantage of the cable curl over a dumbbell variation. Full extension on every rep.
Leaning Back to Assist the Curl: Torso lean is a compensation for too much load. Drop the weight and keep the curl strict.
Rushing the Eccentric: The cable doesn’t let the weight drop on its own the way a dumbbell does. Take advantage of that and lower it with full control on every rep.
Mismatching Load Between Sides: Use the same load on both sides regardless of which feels easier. If one side is consistently stronger, note it and address it but don’t load around the asymmetry.

Alternative Exercises

Dumbbell Curl: The most accessible bilateral bicep curl alternative. Doesn’t provide the same constant tension as the cable (particularly at the bottom of the movement) but allows heavier loading and is practical when a cable machine isn’t available.
Single Arm Band Curl: A band-based alternative that provides accommodating resistance through the curl. Useful when a cable machine isn’t available and a unilateral curl variation is still the goal.

Reps and Sets Recommendations

For Accessory Work: 3-4 sets of 10-15 reps per side at a load that allows full range of motion and a controlled eccentric throughout. Keep rest periods moderate (60-90 seconds) to maintain metabolic tension on the biceps across sets.