Iso Curls Exercise Guide — How to, Benefits, & Alternatives

Iso curls put biceps contraction under more time under tension to aid arm growth. 

Bodybuilders and fitness enthusiasts often perform arm curls to increase their arm muscle mass and strength. When executed with proper form, curls effectively target muscles such as the biceps and brachioradialis (1). Iso curls enhance the effectiveness of traditional curls by keeping the muscles contracted without movement. 

This approach is particularly challenging as it maintains the targeted muscle groups under tension when flexing and resisting extension. The increased time under tension is beneficial for muscle growth (2).

This exercise guide comprehensively analyzes iso curls, detailing the muscles involved and offering a step-by-step guide to performing the exercise. Additionally, it outlines the benefits and suggests alternative exercises that provide similar benefits.

Techniques & Muscles Worked

When performing an iso curl, you keep your arms static, and the muscles experience increased tension to target the wrist flexors, forearms, biceps, and brachialis (elbow flexor muscle). 

The iso curl can be done with dumbbells, cable curls, barbells, and kettlebells. Below is a step-by-step guide on how to do the iso curl exercise properly. We’ll use dumbbells as our free weights for this exercise.

1. Grab the dumbbells with an underhand grip. Extend your arms to your hip area and stand upright with your feet shoulder-width apart.
2. Pull your shoulders down and brace your core (this helps with your stabilization and form). Also, slightly bend your knees while keeping your chest and head up. This is your starting position.
3. Next, slowly curl the dumbbell in one hand until your elbow is bent 90 degrees. Hold your arm and elbows stationary in that 90-degree position.
4. Next, curl the dumbbell in your other hand to your shoulder and return to its starting position to complete the rep.
5. Complete multiple reps while maintaining your elbows at 90 degrees in the static arm.
6. Switch sides and repeat steps 1-5 with the other arm.
7. Repeat for multiple sets.

Benefits

When people think of arm isolation exercises, they think of bicep curls. Iso curls are also an excellent exercise for building muscle mass and strength in your arms and taking curls to the next level. Below are some benefits of doing the iso curls.

Greater Muscle Strength & Size

Standard bicep curls involve regular arm extension and contraction. Iso curls add isometric holds and put all muscles surrounding the arms under extra tension. This activates more muscle fibers, which improves muscle strength and increases muscle mass (3).

Lower Joint Impact

Iso curls are very joint-friendly. Most targets and tensions are on the muscles, and the limited movements place minimal stress on the joints.

Stronger Mind-Muscle Connection

The iso curl is an arm-strengthening exercise that causes the arms to feel under tension. It alienates all other muscle groups and focuses on the primary muscle group, increasing muscle hypertrophy and the mind-muscle connection between the brain and the muscle during the exercise.

Carryover to Other Exercises

Performing the iso curl targets and strengthens your arms. The proper form makes other arm training exercises and routines easier. An example of such exercise is pull-ups, a compound movement that uses your arms as a secondary muscle group.

Core Activation

Doing the iso curl activates core muscles like the abs and obliques. This helps with total body stabilization and posture and prevents injuries.

Stronger Elbow Flexors 

Doing the iso curls works the arms, elbows, muscles, joints, and tissues surrounding them. The continuous tension of the muscles and tissues in the arms and tissues makes them stronger and more resistant.

Iso Curls Alternatives

Integrating iso curls, a vital arm isolation exercise, into your regular workouts can strengthen your arms. However, to avoid a plateau and achieve more effective arm growth, it’s advisable not to limit yourself to this exercise. Below are some alternative iso curl exercises you could mix up to get the most out of your workouts.

Iso Chin-Up

Iso chin-ups are excellent exercises for targeting your arms using isometric holds. All this is done with a chin-up bar and your hands in an underhand grip. Hang from the bar and contract your arms at 90 degrees as you hold that position for 10-12 seconds.

Dumbbell Drag Curl

The dumbbell drag curl is another arm-strengthening exercise. This routine prevents cheating during reps. It’s also perfect for addressing muscle imbalances between arms. The limited movement of the arms creates a good contraction of the biceps since it limits momentum.

Iso Inverted Row

This bodyweight movement requires immense relative strength. The isometric hold adds greater tension to the target muscles, leading to more growth. 

FAQs

What do iso curls work?

Isolation curls work the same muscles as regular curls, including the elbow flexors and forearm muscles.

Are isometric bicep curls good?

Isometric bicep curls are an excellent way to build strength and size in your biceps. The iso holds are particularly effective in recruiting your arm muscle fibers. 

How do you do isometric bicep curls without equipment?

To do isometric bicep curls without equipment, you need a sturdy wall. Then, you can lean against the wall and use your bodyweight for the curl.

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References

1. Coratella, G., Tornatore, G., Longo, S., Toninelli, N., Padovan, R., Esposito, F., & Cè, E. (2023). Biceps Brachii and Brachioradialis Excitation in Biceps Curl Exercise: Different Handgrips, Different Synergy. Sports (Basel, Switzerland), 11(3), 64. https://doi.org/10.3390/sports11030064
2. Prestes, J., A Tibana, R., de Araujo Sousa, E., da Cunha Nascimento, D., de Oliveira Rocha, P., F Camarço, N., Frade de Sousa, N. M., & Willardson, J. M. (2019). Strength and Muscular Adaptations After 6 Weeks of Rest-Pause vs. Traditional Multiple-Sets Resistance Training in Trained Subjects. Journal of strength and conditioning research, 33 Suppl 1, S113–S121. https://doi.org/10.1519/JSC.0000000000001923
3. Ingebrigtsen, J., Holtermann, A., & Roeleveld, K. (2009). Effects of load and contraction velocity during three-week biceps curls training on isometric and isokinetic performance. Journal of strength and conditioning research, 23(6), 1670–1676. https://doi.org/10.1519/JSC.0b013e3181b3f37b