Breaststroke Scissor Kick: Correcting Knee Abduction and Strengthening Muscles

Introduction

The breaststroke kick is the stroke that requires the most coordination among the hip, knee, and ankle joints of any swimming stroke. The “scissor kick”—where the knees splay excessively outward and the heels turn inward during the kick—is the most common technical error in breaststroke and the one most likely to cause knee injuries. Many swimmers don’t even realize they have a scissor kick problem until the medial collateral ligament in the knee sends out a pain warning.

What Is a Scissor Kick?

In a proper breaststroke kick, after the feet sweep outward, the kick is completed by “pushing water backward with the soles of the feet,” and the legs finally come together. A scissor kick refers to:

Causes of the Scissor Kick

Insufficient Hip External Rotation Mobility

The breaststroke kick requires good hip external rotation mobility. When mobility is insufficient, swimmers compensate by splaying the knees excessively outward to “create” kicking space, resulting in a scissor kick.

Weak Adductor Muscles

The closing phase of the breaststroke kick relies on the adductor muscles (inner thigh). When the adductors are weak, leg closure is poorly controlled, and the legs often cross over each other in a scissor-like motion rather than coming together smoothly.

Incorrect Motor Learning

Some swimmers misunderstand the breaststroke kick as “kicking the feet outward,” so they deliberately whip their feet to the sides, forming a scissor kick habit.

Habitual Ankle External Rotation

If the ankle has a tendency toward habitual external rotation (pigeon-toed), the soles of the feet cannot face backward properly during the kick, greatly reducing efficiency and subjecting the knees to abnormal lateral torque.

How the Scissor Kick Harms the Knees

The lateral forces generated by the breaststroke kick should normally be absorbed by the hip joint. With a scissor kick, this lateral force is transmitted directly to the knee joint, causing:

• Chronic Medial Collateral Ligament (MCL) Sprain: Accumulated stress from repeated outward splaying
• Patellar Cartilage Wear: The knee bends repeatedly along an abnormal track
• Pes Anserine Tendinitis: Excessive load on the tendons on the inner side of the knee

Corrective Exercise Program

Dry-Land Corrective Exercises

Resistance Band Adduction Exercise: Sit on a chair with a resistance band looped around the outside of your thighs, and practice adducting your knees against the band’s resistance. Do 3 sets of 15 repetitions. This strengthens adductor muscle control.

Mirror Breaststroke Kick Simulation: Stand in front of a full-length mirror and simulate the breaststroke kick, observing whether your knees extend beyond your toes. Immediate visual feedback helps the brain establish the correct movement pattern.

Supine Breaststroke Kick: Lie on your back on a mat and practice the breaststroke kick. With gravity assisting, it’s easier to feel the direction of pushing water backward with the soles rather than whipping outward.

In-Water Corrective Exercises

Kickboard Breaststroke Kick: Hold a kickboard with both hands and focus solely on the leg action. Pause for 2 seconds after each kick to confirm the movement path is correct before kicking again. Slow, segmented practice allows the nervous system to relearn the correct path.

Narrow Breaststroke Kick: Deliberately reduce the width of knee splaying during the kick (no wider than shoulder width), and feel the difference in force between “pushing water” versus “whipping water.” Propulsion will initially decrease, but once the technique is established, efficiency actually improves.

Improving Hip Mobility

• Butterfly Stretch: Sit on the floor with the soles of your feet together, press both knees toward the ground, and hold for 30-60 seconds. Improves hip external rotation mobility.
• Pigeon Pose: Yoga pigeon pose, holding each side for 1-2 minutes, deeply improves hip range of motion.
• Squat Mobility Exercise: Full squat with heels flat on the ground, using both elbows to push the knees outward, improving overall coordination of hip, knee, and ankle mobility.

Practical Recommendations

• If your knee is already painful, rest for 1-2 weeks first, apply ice to reduce inflammation, then begin corrective exercises within a pain-free range.
• Do a 5-minute hip mobility warm-up before every swim, including butterfly stretches and leg circles, to help the kick move more fluidly.
• Use ankle bands for assisted training: Loop a rubber band around the ankles to restrict ankle external rotation, forcing the soles to face the correct direction.
• Long-term goal: Correcting breaststroke kick technique typically requires 6-8 weeks of deliberate practice, during which you should also work on hip mobility and adductor strengthening to address the root cause.

Related Reading

• Swimmer’s Knee: The Complete Guide to Breaststroke Knee Injuries
• Breaststroke Out-Sweep and In-Sweep: Balancing Knee Protection and Propulsive Force
• Knee Problems in Swimming: Causes, Prevention, and Rehabilitation of Breaststroke Knee
• Breaststroke Leg Kick Technique: Balancing External Rotation Angle and Knee Protection