One-Arm Tricep Extension (Cable)
The One-Arm Tricep Extension is a unilateral cable exercise that isolates the triceps muscles to build arm size and strength. By working one arm at a time, it helps correct muscle imbalances and allows for a full range of motion.
Because this is a unilateral movement, the AI analyzes performance differences between your left and right arms to identify and correct strength asymmetries over time. By tracking your RPE and fatigue levels, the app auto-regulates volume to ensure you stimulate the triceps without overstressing the elbow joints, which can be sensitive to overuse. Additionally, recovery data helps determine if you should focus on lighter, high-repetition sets for metabolic stress or heavier loads for strength based on your current readiness.
Form Cues
- Keep your upper arm vertical and close to your head throughout the set
- Extend your forearm upward until the arm is fully straight
- Squeeze the tricep hard at the point of full extension
- Control the cable slowly as you lower the weight back behind your head
- Maintain a neutral wrist position to protect the joint
- Don't let your elbow flare out to the side excessively
- Don't use body momentum or arch your back to move the weight
- Don't allow your elbow to drift forward or backward during repetitions
- Don't cut the range of motion short at the top or bottom
Common Mistakes
- Flaring the elbow out sideways
- Using momentum to swing the weight up
- Moving the upper arm during the rep
- Arching the lower back excessively
- Using a weight that prevents full extension
Muscles Worked
This exercise primarily targets the long head of the triceps brachii due to the overhead position, which places that specific muscle head in a stretched position. It also engages the lateral head as a secondary mover, helping to build overall arm thickness and correct left-to-right strength imbalances.
Primary
Secondary
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