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Exercise Overview

The Kettlebell Single Arm Curl is an effective unilateral isolation exercise that develops biceps strength while improving grip, forearm endurance and arm stability. Unlike a traditional dumbbell curl, the offset centre of mass of a kettlebell creates a unique loading pattern that challenges the muscles throughout the movement and requires greater control from the wrist, forearm and shoulder stabilisers.

Training one arm at a time allows you to focus on technique, identify and correct muscular imbalances, and develop equal strength on both sides of the body. The exercise is suitable for beginners and experienced lifters alike, particularly those looking to improve functional strength or incorporate kettlebells into an upper-body training programme.

Although the biceps brachii performs most of the work, the brachialis, brachioradialis, forearm muscles and shoulder stabilisers all contribute to producing a smooth, controlled movement.

Quick Facts

Primary Muscle

Biceps Brachii

Secondary Muscles

• Brachialis
• Brachioradialis
• Forearm Flexors
• Forearm Extensors

Stabilising Muscles

• Anterior Deltoid
• Rotator Cuff
• Upper Trapezius
• Core

Exercise Type

Isolation

Movement Pattern

Elbow Flexion

Equipment

Kettlebell

Difficulty

Beginner to Intermediate

Mechanics

Isolation

Force Type

Pull

Muscles Worked

Primary Muscle

• Biceps Brachii

Secondary Muscles

• Brachialis
• Brachioradialis
• Wrist Flexors
• Wrist Extensors

Stabilising Muscles

• Anterior Deltoid
• Rotator Cuff
• Upper Trapezius
• Rectus Abdominis
• Obliques
• Erector Spinae

The offset weight distribution of the kettlebell requires continuous stabilisation throughout the curl, making the forearms and grip work harder than during many traditional dumbbell curls.

How to Perform the Kettlebell Single Arm Curl

1. Stand upright with your feet approximately shoulder-width apart.
2. Hold a kettlebell in one hand using a neutral grip.
3. Allow the kettlebell to hang naturally beside your thigh.
4. Engage your core and keep your chest lifted.
5. Keep your elbow close to your torso throughout the movement.
6. Curl the kettlebell upward by bending your elbow.
7. Continue until your forearm approaches your upper arm.
8. Pause briefly while squeezing your biceps.
9. Lower the kettlebell slowly under control to the starting position.
10. Complete the desired repetitions before switching arms.

Avoid allowing your elbow to drift forward or using body momentum to lift the kettlebell.

Video

Breathing Technique

• Inhale before beginning the repetition.
• Exhale as you curl the kettlebell upward.
• Pause briefly at the top.
• Inhale while lowering the kettlebell slowly.
• Maintain controlled breathing throughout the set.

Benefits

Develops Stronger Biceps

The exercise effectively isolates the elbow flexors, making it valuable for increasing arm strength and muscle size.

Improves Grip Strength

The thick handle and offset weight of a kettlebell require greater grip activation than many traditional curling exercises.

Corrects Strength Imbalances

Training one arm independently helps identify weaker sides and promotes balanced muscular development.

Enhances Forearm Development

The unstable load increases activation of the forearm muscles responsible for grip and wrist stability.

Improves Functional Strength

The unique loading characteristics of kettlebells better replicate many real-world lifting and carrying movements.

Common Mistakes

Swinging the Body

Using momentum reduces muscle activation and places unnecessary stress on the lower back.

Moving the Elbow Forward

The elbow should remain close to the side to keep tension on the biceps.

Curling Too Quickly

Fast repetitions reduce time under tension and often compromise technique.

Dropping the Weight

Control the lowering phase to maximise muscle stimulation and reduce injury risk.

Using Excessive Weight

Choose a kettlebell that allows strict form throughout every repetition.

Expert Tips

• Keep your wrist straight throughout the movement.
• Focus on moving only your forearm.
• Avoid leaning backwards during the curl.
• Lower the kettlebell more slowly than you lift it.
• Fully straighten your arm between repetitions without locking the elbow aggressively.
• Maintain continuous tension on the biceps throughout the set.

Variations

• Alternating Kettlebell Curl
• Double Kettlebell Curl
• Hammer Kettlebell Curl
• Cross-Body Kettlebell Curl
• Seated Kettlebell Curl
• Incline Curl with Kettlebell
• Bottoms-Up Kettlebell Curl
• Resistance Band Curl

Alternative Exercises

• Standing Dumbbell Curl
• Hammer Curl
• EZ Bar Curl
• Barbell Curl
• Concentration Curl
• Cable Curl
• Preacher Curl
• Bayesian Cable Curl
• Reverse Curl
• Zottman Curl

Programming

Muscle Growth

• 3–4 sets
• 8–12 repetitions per arm
• 60–90 seconds rest

Strength

• 4–5 sets
• 5–8 repetitions per arm
• 2 minutes rest

Muscular Endurance

• 2–3 sets
• 15–20 repetitions per arm
• 30–60 seconds rest

Suitable For

This exercise is suitable for:

• Beginners
• Intermediate lifters
• Advanced athletes
• Functional fitness enthusiasts
• Home gym users
• Strength training programmes
• Arm hypertrophy programmes
• Grip strength development

Avoid If

You may need to modify or avoid this exercise if you have:

• Acute elbow injuries
• Significant wrist pain
• Severe forearm tendon irritation
• Recent shoulder injuries that limit arm movement

Seek advice from a qualified healthcare professional before training through pain.

Frequently Asked Questions

Is a kettlebell curl harder than a dumbbell curl?

Many people find kettlebell curls more challenging because the centre of mass sits below the handle. This creates additional instability, requiring greater grip strength and forearm activation.

What muscles does the Kettlebell Single Arm Curl work?

The exercise primarily targets the biceps brachii while also recruiting the brachialis, brachioradialis, forearms and shoulder stabilisers.

Can beginners perform this exercise?

Yes. Beginners should start with a light kettlebell and focus on mastering proper technique before increasing the weight.

Should I perform all repetitions on one arm first?

Yes. Completing all repetitions on one arm before switching sides generally allows better concentration and helps identify strength differences between arms.

How heavy should the kettlebell be?

Choose a kettlebell that allows controlled repetitions with a full range of motion. Good technique should always take priority over heavier loads.

Related Exercises

• Standing Dumbbell Curl
• Alternate Hammer Curl
• Cross-Body Hammer Curl
• Double Kettlebell Curl
• Bottoms-Up Kettlebell Curl
• EZ Bar Curl
• Concentration Curl
• Cable Curl
• Reverse Curl
• Zottman Curl

Exercise Summary

The Kettlebell Single Arm Curl is an excellent isolation exercise for building stronger, more muscular arms while improving grip strength and unilateral control. The offset weight of the kettlebell provides a different training stimulus compared to traditional dumbbells, increasing forearm and stabiliser muscle involvement throughout the movement. Whether used as part of a bodybuilding programme, functional fitness routine or general strength workout, it offers an effective way to develop balanced arm strength and improve upper-body performance.