Upper Arms Exercise · Cable

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Cable Concentration Extension (on Knee)

Resting the elbow on the knee while extending against a low cable isolates the triceps in a fixed position, similar to a concentration curl but for the opposite muscle. Because the arm can't drift, cheating the extension with shoulder movement is much harder than on a standing cable pushdown. It's a good exercise for chasing the mind-muscle connection in a muscle group that's often trained on autopilot.

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Category

Upper Arms

Equipment

Cable

Target

Triceps

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Exercise reference published by PlanWorkouts; see our editorial standards.

How to Do the Cable Concentration Extension (on Knee)

1. Take a seat on a bench or chair with your knees bent and both feet flat on the floor.
2. Grip the cable handle in your right hand and brace your elbow against the inside of your right knee.
3. Straighten your arm all the way, pinning your elbow in place against your knee.
4. Hold briefly once fully extended, then bring your arm back down slowly to the start.
5. Continue for your target number of reps, then repeat on the other side.

Technique & Form Tips

Focus on controlled elbow extension while keeping your upper arms fixed in the position required by your specific variation, such as a pushdown or overhead extension. Manage your range of motion based on your own comfort during both flexion and extension.

Common Mistakes to Avoid

• Elbow migration: Keep the upper arm stationary to prevent the movement from turning into a different exercise.
• Inconsistent elbow tracking: Follow the intended path for your elbows to ensure they do not excessively flare outward.
• Forcing the end position: Straighten and bend the elbow through a controlled, comfortable range without snapping into the end position.

How to Breathe During This Exercise

Breathe continuously, matching your inhale and exhale to the pace of your repetitions.

Comfort and Control

Choose a load and range you can control. Stop if the movement causes pain. If discomfort persists, stop and ask a qualified professional about an appropriate exercise and range.

General guidance: Mayo Clinic on weight-training technique. Follow the specific movement steps above for this variation.

Muscles Worked

The Cable Concentration Extension (on Knee) mainly targets your Triceps, with your Forearms helping support the movement.

More Upper Arms Exercises

Assisted Standing Triceps Extension (with Towel) Assisted · Triceps Assisted Triceps Dip (kneeling) Leverage Machine · Triceps Band Alternating Biceps Curl Band · Biceps Band Close-Grip Push-Up Band · Triceps Band Concentration Curl Band · Biceps Band One Arm Overhead Biceps Curl Band · Biceps

More Triceps Exercises

Band Side Triceps Extension Band · Triceps Barbell Close-Grip Bench Press Barbell · Triceps Barbell Decline Close Grip To Skull Press Barbell · Triceps Barbell Incline Close Grip Bench Press Barbell · Triceps Barbell Incline Reverse-Grip Press Barbell · Triceps Barbell Jm Bench Press Barbell · Triceps

Equipment Alternatives

Don't have cable? These target the same triceps with different equipment.

Body-Up Body Weight · Triceps Band Side Triceps Extension Band · Triceps Barbell Decline Close Grip To Skull Press Barbell · Triceps Dumbbell Close Grip Press Dumbbell · Triceps

FAQ

What muscles does the Cable Concentration Extension (on Knee) work?

The Cable Concentration Extension (on Knee) mainly works your triceps. Your forearms also works to help support and steady your body. Using good, smooth form makes sure you work the right muscles and avoid unnecessary strain on your joints.

What equipment do I need for the Cable Concentration Extension (on Knee)?

You do the Cable Concentration Extension (on Knee) with a cable. Make sure your equipment is set up safely before starting. If you work out at home or have limited gear, check out our alternative exercises below.

What form mistake should I watch for on the Cable Concentration Extension (on Knee)?

One mistake to watch for is elbow migration: Keep the upper arm stationary to prevent the movement from turning into a different exercise.. Use a comfortable range and a controlled return; reduce the load if you cannot maintain the demonstrated setup.

How many sets and reps should I perform on the Cable Concentration Extension (on Knee)?

To tone and grow muscle, do 3 to 4 sets of 10 to 15 smooth reps with 60 seconds of rest, focusing on a full stretch and squeezing the muscle at the top of each rep.

What's a good alternative to the Cable Concentration Extension (on Knee)?

The Body-Up trains your triceps with body weight and a similar movement pattern. Review its form guide before substituting it, since setup and range of motion can differ.