Muscles Worked With Kettlebell Swings

Originally published June 2019. Updated February 2026.

In 2012, Dr. Stuart McGill — one of the world’s leading spine biomechanics researchers — published the first study to measure muscle activation and spinal loading during kettlebell exercises. Using electromyography on subjects swinging a 16 kg kettlebell, his lab recorded gluteus maximus activation at 76% of maximum voluntary contraction, rapid-fire bracing cycles across the entire posterior chain, and a spinal loading pattern opposite in direction to traditional lifts — providing the first biomechanical explanation for why so many people credit kettlebell swings with fixing their back.²

That study opened the door. Since then, multiple peer-reviewed EMG studies have mapped exactly which muscles work during the swing, how hard they work, and when they activate. Here is what they found.

In This Article

• What Muscles Do Kettlebell Swings Work?
• The Full EMG Breakdown
• When Each Muscle Activates During the Swing Cycle
• One-Arm vs Two-Arm Swing: What Changes?
• How to Kettlebell Swing
• Warming Up for the Kettlebell Swing
• Teaching the Kettlebell Swing
• Swing Variations Work Different Muscles
• References
• Frequently Asked Questions

What Muscles Do Kettlebell Swings Work?

The kettlebell swing is a full-body exercise. Here are the muscle groups involved:

• Gluteus maximus — primary driver of hip extension (76% MVC²)
• Hamstrings — semitendinosus, semimembranosus, biceps femoris (73–115% MVC³)
• Erector spinae — iliocostalis, longissimus, spinalis (~50% MVC²)
• Core — rectus abdominis, external and internal obliques, gluteus medius (70% MVIC⁵)
• Quadriceps — vastus lateralis, rectus femoris⁴
• Latissimus dorsi — force transfer and shoulder stabilization
• Forearm flexors — grip strength and endurance
• Rhomboids, lower trapezius, levator scapulae — posture and shoulder blade control
• Gastrocnemius, soleus — ankle stabilization and balance

That is the quick answer. But if you train with kettlebells — or plan to — the list alone is not enough. Knowing which hamstring the swing targets could determine whether it helps or hurts your knees. Knowing when your glutes actually fire during the cycle changes how you cue the movement. And knowing that different swing variations produce measurably different muscle activation means “do kettlebell swings” is not a complete instruction.

The research below covers all of it — the full breakdown by muscle group, when each muscle activates during the swing cycle, what changes with a one-arm swing, and why the variation you choose matters.

The Full EMG Breakdown

This section covers the two-handed hip hinge swing — the most commonly taught variation. Other swing variations produce measurably different results; those differences are covered further down.

Prime Movers (Hip and Knee Extension)

These are the muscles that drive the swing — they produce the movement.

Gluteus maximus — The primary driver of hip extension. McGill and Marshall (2012) recorded peak gluteus maximus activation of 76% of maximal voluntary contraction (MVC) during the two-handed swing with a 16 kg kettlebell.² The gluteal muscles experienced their greatest activation at 57% of the swing cycle — corresponding to the final degrees of hip extension as you stand tall at the top.² This is why the cue “squeeze your glutes at the top” exists: peak glute activation coincides with full hip lockout.

Hamstrings (semitendinosus, semimembranosus, biceps femoris) — The hamstrings assist hip extension and control the eccentric deceleration during the backswing. In the hip hinge swing, the medial hamstring (semitendinosus) is targeted more than the lateral hamstring (biceps femoris). Zebis and colleagues (2012) measured this in elite female handball and soccer players and found semitendinosus activation reaching 73–115% of MVC — levels the researchers described as “very high.”³ This is significant because the semitendinosus plays a key role in dynamic knee stability and in preventing excessive valgus and external rotation of the knee joint.³ The authors concluded that the kettlebell swing has direct implications for injury prevention and rehabilitation — making it one of the few exercises that builds posterior chain strength and protects the knee joint at the same time.

Quadriceps (vastus lateralis, rectus femoris) — The quadriceps contribute to knee extension during the upswing. EMG comparison across kettlebell exercises found significantly higher vastus lateralis activation during the swing than during the clean.⁴

Spinal Stabilizers

Erector spinae (iliocostalis, longissimus, spinalis) — The erector spinae muscles maintain spinal position throughout the swing. They work at approximately 50% MVC during the two-handed swing,² creating the rapid activation-relaxation cycles that characterize the exercise. This pulsing pattern — brace, release, brace, release — is one reason kettlebell swings are associated with improved back health. McGill and Marshall found that spine compression during the swing was conservative at less than 3,200 N, and identified a unique posterior shear of L4 on L5 that is opposite in direction to traditional lifts.² This opposite loading pattern helps explain why many people report that swings reduce back pain, while a few find that swings aggravate it.

Latissimus dorsi — The lats pull the shoulders down and back, keeping the shoulder joint packed and safe during the swing. They also contribute to force transfer between the lower and upper body. This muscle creates the “shoulder away from the ears” position at the top of the swing.

Core

Rectus abdominis, external obliques, internal obliques — The abdominal muscles brace the trunk to protect the spine during the rapid acceleration and deceleration of the swing. McGill and Marshall observed that abdominal muscular pulses — brief, intense contractions timed to the swing cycle — create the bracing pattern unique to kettlebell training.² The swing is not a crunch; the abs work isometrically to resist extension, not create flexion.

Gluteus medius — Often overlooked, the gluteus medius stabilizes the pelvis during the swing. Van Gelder and colleagues measured gluteus medius activation of approximately 70% MVIC during the two-handed swing⁵ — well above the 50–60% threshold needed to produce a strengthening stimulus.⁵

Grip

Forearm flexors (flexor digitorum superficialis, flexor digitorum profundus, lumbricals) — Your swing is only as good as your grip. If your grip fails, the set ends. The forearm flexors maintain hold on the handle throughout the swing. With high-rep training, grip endurance often becomes the limiting factor before any other muscle fatigues. One critical detail: a grip that stays maximally tight throughout the entire swing will create unnecessary forearm fatigue and can lead to injury with high volume. The grip should tighten during the backswing and the acceleration phase, and relax slightly at the top. For more on grip, download the free Master Kettlebell Grips PDF.

Posture and Shoulder Stabilization

Rhomboids (minor and major), lower trapezius, levator scapulae — These muscles retract and depress the shoulder blades, maintaining a strong upper back position. At the top of the swing, the chest is out, the shoulder blades are slightly pulled together and down. Losing this position — letting the shoulders round forward or shrug up — puts the shoulder joint at risk.

Lower Leg

Gastrocnemius, soleus — The calf muscles stabilize the ankle joint and contribute to maintaining balance during the rapid weight shift of the swing. They also assist in the final push through the ground during hip extension.

When Each Muscle Activates During the Swing Cycle

Understanding which muscles work when during the swing cycle helps coaches identify errors and helps athletes focus their effort correctly.

The swing cycle can be broken into phases. Based on McGill and Marshall (2012)² and Van Gelder et al. (2015):⁵

Backswing (eccentric/loading phase): The kettlebell passes between the legs. The hamstrings lengthen under load as the hips hinge back. The erector spinae brace to maintain spinal position. The forearm flexors grip tightly. The hamstrings (specifically the biceps femoris) activate before the gluteus maximus during this phase.⁵

Acceleration phase (concentric/drive): The hips extend explosively. The glutes and hamstrings contract powerfully. The quads extend the knees. The erector spinae continue to stabilize.

Terminal swing (top of the swing): The gluteus maximus reaches peak activation — 76% MVC — at this point in the cycle.² The abs brace to prevent spinal hyperextension. The shoulder stabilizers hold the arms in position. The grip relaxes slightly.

Return phase (deceleration): The kettlebell falls. The hamstrings and hip flexors control the descent. The grip re-engages. The cycle repeats.

One finding consistently reported across studies: the biceps femoris activates before the gluteus maximus during the swing.⁵ This contradicts the commonly taught clinical sequence where the glutes should fire first, and means that adequate hamstring conditioning is a prerequisite for safe swinging.

For the full phase-by-phase analysis, read What Happens During a Kettlebell Swing?

One-Arm vs Two-Arm Swing: What Changes?

Switching from a two-arm to a one-arm swing changes the demands significantly, especially on the core.

Andersen and colleagues (2016) found that the one-arm swing produced significantly higher activation of the upper erector spinae on the side opposite the working arm — 14–25% higher than the same side.⁶ This makes sense: with the load offset to one side, the contralateral back muscles must work harder to resist lateral flexion and rotation.

The rectus abdominis showed the opposite pattern: the two-arm swing produced higher rectus abdominis activation (40–59% higher) than the one-arm swing on both sides.⁶

What this means practically: the two-arm swing is better for training the anterior core (abs), and the one-arm swing is better for training anti-rotation and lateral stabilization. Both have value and both should be included over time. If you’re transitioning from two-arm to one-arm swings, reduce the weight and invest in the additional core conditioning required. More detail in 1 Arm versus 2 Arm Kettlebell Swing.

How to Kettlebell Swing

The following video summarizes the content from the book Master The Basic Kettlebell Swing, also available on Amazon in Kindle or paperback format.

Note: This video is a few years old and the production quality reflects that — but the technique instruction is solid and still holds up, which is why we continue to use it here.

Warming Up for the Kettlebell Swing

The following video covers a muscle priming routine used before starting the kettlebell swing. Priming is not the same as warming up — it’s the process of activating the specific muscles that will do the work before you load them. This improves the mind-muscle connection and prepares the neuromuscular system for the rapid activation-relaxation cycles that the swing demands.

Teaching the Kettlebell Swing

The following drill is used for teaching the deep hip hinge insert — the point during the backswing where the hamstrings pull the hips further back and down to actively insert the kettlebell between the legs rather than letting it pendulum freely. This insert is what separates a controlled swing from one with kettlebell bobbing, a common beginner problem.

Swing Variations Work Different Muscles

Everything above covers the two-handed hip hinge swing. But the kettlebell swing is a base exercise — “swing” describes the path of the weight (a pendular arc), not the movement pattern of the body. Different movement patterns produce different muscle activation.

Del Monte and colleagues (2020) compared three swing styles — hip hinge, squat, and double knee extension — and found statistically significant differences in hamstring activation across all three.¹ The hip hinge swing produced the greatest hamstring EMG activity (p=0.002 vs squat, p=0.020 vs double knee extension).¹

Here is what changes with each variation:

Hip hinge swing (this article) — Hips travel backward, torso tilts forward, knees bend minimally. Highest hamstring and glute activation. Best for posterior chain strength and power.

Squat swing — Greater knee flexion, hips drop lower, torso stays more vertical. Higher quadriceps involvement. More muscles recruited overall, which spikes heart rate faster — useful for interval training and cardio.

Double knee extension swing (also known as the pendulum swing, Girevoy Sport swing, or sport style swing) — Uses a double knee bend during the cycle to allow the hamstring stretch reflex for efficient energy recycling. Designed for high-rep endurance work in kettlebell sport.

Each variation is a valid exercise. The choice depends on your training goal. The problem occurs when a coach programs “kettlebell swings” without specifying which variation — because the outcomes are different.

For the complete breakdown: The Kettlebell Swing Is Not a Hip Hinge and The Difference Between Kettlebell Swing Variations.

What About the American Swing?

The American swing takes the kettlebell overhead. This adds involvement of the anterior deltoids, pectoralis major, serratus anterior, coracobrachialis, and biceps brachii to get the bell to the top position. If you want to be efficient with the American swing, stay safe, and be able to perform high reps, lay the foundation with the conventional kettlebell swing first and then continue that knowledge through the kettlebell snatch.

Ready to Start?

If you’re new to kettlebells, the swing is one of the most important exercises to learn — but it also has one of the highest learning curves. Done right, it builds strength, endurance, power, and grip. Done wrong, it causes the exact injuries it’s supposed to prevent.

Our Beginner Kettlebell Workout includes technique videos, common mistakes to avoid, programming, and a follow-along workout. For a deeper understanding of kettlebell training from the ground up, see our Kettlebell Training Fundamentals book or enroll in the Online Kettlebell Certification.

Other Kettlebell Swing Resources

• What height should I swing a kettlebell?
• What kettlebell weight to choose?
• How explosive should your kettlebell swing be?
• Kettlebell swing benefits
• Free Master Kettlebell Grips PDF
• Become kettlebell certified
• List of all 400+ kettlebell exercises

Related Articles

• The Kettlebell Swing Is Not a Hip Hinge — why “swing” describes the weight’s path, not the body’s movement
• The Difference Between Kettlebell Swing Variations — hip hinge, squat, pendulum, Hardstyle
• What Happens During a Kettlebell Swing? — full phase-by-phase muscle activation analysis
• 1 Arm versus 2 Arm Kettlebell Swing — the transition and what changes
• Kettlebell Swing Benefits — cardiovascular, muscular endurance, power, and more

References

1. Del Monte, M.J., Opar, D.A., Timmins, R.G., Ross, J.A., Keogh, J.W.L., & Lorenzen, C. (2020). “Hamstring myoelectrical activity during three different kettlebell swing exercises.” Journal of Strength and Conditioning Research, 34(7): 1953–1958. PMID: 28930870. https://pubmed.ncbi.nlm.nih.gov/28930870/

2. McGill, S.M., & Marshall, L.W. (2012). “Kettlebell swing, snatch, and bottoms-up carry: back and hip muscle activation, motion, and low back loads.” Journal of Strength and Conditioning Research, 26(1): 16–27. PMID: 21997449. https://pubmed.ncbi.nlm.nih.gov/21997449/

3. Zebis, M.K., Skotte, J., Andersen, C.H., et al. (2012). “Kettlebell swing targets semitendinosus and supine leg curl targets biceps femoris: an EMG study with rehabilitation implications.” British Journal of Sports Medicine, 47(18): 1192–1198. PMID: 22736206. https://pubmed.ncbi.nlm.nih.gov/22736206/

4. Lyons, B.C., Mayo, J.J., Tucker, W.S., Wax, B., & Hendrix, R.C. (2017). “Electromyographical comparison of muscle activation patterns across three commonly performed kettlebell exercises.” Journal of Strength and Conditioning Research, 31(9): 2363–2370. PMID: 28394829. https://pubmed.ncbi.nlm.nih.gov/28394829/

5. Van Gelder, L.H., Hoogenboom, B.J., Alonzo, B., Briggs, D., & Hatzel, B. (2015). “EMG analysis and sagittal plane kinematics of the two-handed and single-handed kettlebell swing: a descriptive study.” International Journal of Sports Physical Therapy, 10(6): 811–826. PMID: 26618061. https://pubmed.ncbi.nlm.nih.gov/26618061/

6. Andersen, V., Fimland, M.S., Gunnarskog, A., Jungård, G.A., Slåttland, R.A., Vraalsen, Ø.F., & Saeterbakken, A.H. (2016). “Core muscle activation in one-armed and two-armed kettlebell swing.” Journal of Strength and Conditioning Research, 30(5): 1196–1204. PMID: 26473519. https://pubmed.ncbi.nlm.nih.gov/26473519/

Frequently Asked Questions