Cable Single-Arm Curl
What Is the Cable Single-Arm Curl?
Cable Single-Arm Curl is an isolation exercise that primarily targets the biceps and also engages the brachialis, brachioradialis and forearm flexors. It is a beginner-level movement, done standing and facing a low pulley with one handle, that suits anyone building arm size, elbow flexion strength or side-to-side balance.
This variation is ideal for focusing on one arm at a time, helping correct strength or size imbalances between sides. With only one arm working, the stronger side cannot take over, and the trunk has to hold steady against the one-sided pull instead of helping the weight up.
Because the cable pulls toward the pulley rather than straight down, it keeps tension on the biceps at the bottom of the curl, where a hanging dumbbell loads the arm very little. Standing a little farther from the stack adds to that tension at the start of each rep, and as with most curls the load eases as the hand nears the shoulder. This makes the single-arm cable curl especially useful as a finishing movement in a biceps workout or for isolation-focused training.
Small changes shift the work. Turning the palm to face in changes how the biceps, brachialis and brachioradialis share the work, as in the Cable Rope Hammer Curl, while bracing the upper arm on a pad in the Cable Single-Arm Preacher Curl removes the need to hold the elbow still yourself. Anyone new to curling can learn the pattern here with light weight, since the cable guides the arm and moves smoothly.
Muscles Worked
- Biceps Brachii
- Primary
- Brachialis
- High
- Brachioradialis
- Medium
- Deltoid
- Minimal
- External Oblique
- Minimal
Instructions
- Set the pulley on a cable machine to the lowest position and attach a single handle.
- Grasp the handle in one hand with an underhand grip and stand facing the machine, a step or two back so the cable stays taut with your arm straight.
- Stand tall with your feet about hip-width apart and let your free arm hang at your side.
- Let your working arm hang fully extended with the palm facing forward and keep your elbow close to your torso.
- Curl the handle upward by contracting your biceps, keeping the elbow stationary.
- Continue until your hand reaches shoulder height and your palm faces your shoulder.
- Keep your torso square to the machine without leaning back or twisting toward the cable.
- Squeeze at the top of the movement, then slowly lower the handle back to the starting position.
- Complete all reps on one side before switching arms.
Common Mistakes
Using momentum
Swinging the arm or torso to lift the weight reduces effectiveness and increases injury risk.
Elbow drifting forward
Moving the elbow forward during the curl shifts the load away from the biceps.
Turning the wrist
Rotating or curling the wrist at the top can strain forearm tendons and reduce biceps isolation.
Rushing the movement
Fast, uncontrolled reps reduce time under tension and increase risk of poor form.
Twisting toward the cable
Letting the torso rotate or lean toward the working side turns the curl into a whole-body pull and takes load off the biceps.
Standing too close to the stack
Standing right over the pulley lets the cable go slack or the weights touch down at the bottom, so the biceps lose tension between reps.
Injuries
Cable Single-Arm Curl is a low risk exercise when performed with proper technique.
Loads are usually modest and the movement is simple, so problems usually come from too much weight, too much volume or jerking the handle out of the bottom. These can irritate the tendons at the front of the elbow or strain the wrist over time, and leaning back or twisting to finish a rep moves stress into the lower back and shoulder.
To stay safe, focus on controlled reps and keep your wrist in a neutral position throughout the movement. Let the arm straighten under control at the bottom rather than letting the cable snap the elbow open. If you experience any discomfort in the shoulder or elbow, check your elbow placement and range of motion, and consider using lighter weight. To regress, curl seated or use a lighter pin, or switch to the Band Curl; once the pattern is solid, the Cable Single-Arm Preacher Curl offers a stricter version.
Stop the set if you feel sharp pain at the front of the elbow. A sudden pop, bruising, a change in the shape of the biceps or new weakness when turning the palm up needs prompt medical assessment.
Frequently Asked Questions
- Q: Should I do this exercise at the start or end of my workout?
It works well as a finisher or accessory movement later in your session.
- Q: Can I do this seated?
Yes, performing it seated can help reduce body movement and increase focus.
- Q: How heavy should I go on single-arm cable curls?
Use a weight that allows you to maintain perfect form for 10 to 15 reps per arm.
- Q: Should I face the machine or stand side-on?
Facing the low pulley is the standard setup and the one shown here. Standing side-on with the working arm nearest the machine also works and changes where the curl feels hardest, so use whichever position lets you keep the elbow pinned at your side.
- Q: Which arm should I start with?
Start with your weaker arm and match its reps with the stronger one. That keeps the stronger side from getting extra work and lets the gap between arms close over time.
- Q: Does curling with the arm behind my body build more muscle?
Not necessarily. In a 10-week study of untrained men, single-arm cable curls with the upper arm at the side built about as much elbow flexor thickness as curls with the shoulder held extended behind the body, when range of motion and effort were matched. Choose the version that lets you keep the elbow still and train close to failure.