Taekwondo Roundhouse Kick Kinetic Chain

Kick Mechanics

Hip rotation power 1.00×

Knee snap (whip) gain 1.00×

Stance width 1.00×

Target distance 1.05 m

Ready — press Execute Kick

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Peak hip ω

0 °/s

Peak knee ω

0 °/s

Foot impact speed

0.0 m/s

Impact force (est.)

0 N

Chain efficiency

0 %

Kick phase

idle

How it works

The roundhouse kick (dollyo chagi) is the textbook example of the kinetic (summation-of-speed) chain: a large proximal segment starts the motion and decelerates just as it hands its angular momentum to the next, smaller, distal segment — hip rotation → thigh swing → knee extension → foot. Each handoff multiplies linear speed at the tip, the same principle behind a whip crack or a baseball throw.

Segment angular velocity:  ω = dθ / dt
Foot linear velocity:      v = |Δr_foot / Δt|   (numerical forward kinematics
                                                  of the hip→knee→foot chain)
Impact force (impulse):    F ≈ m_eff · Δv / Δt_contact
Chain efficiency:          η = v_foot,peak / (ω_hip,peak · L_leg)

Hip rotation power — how hard the supporting leg pivots the pelvis; raises peak hip angular velocity ω_hip and shortens the whole kick's duration.
Knee snap (whip) gain — how sharply the knee converts stored chamber angle into extension speed; this is the term sports scientists call the "whip effect" and it dominates foot-tip speed.
Stance width — widens the chamber angle and effective lever arm, trading a slightly slower cycle for more reach and torque.
Target distance — the pad's stand-off; too close and the kick strikes before full extension, too far and it whips past at reduced or zero contact speed — exactly like a real timing/distancing error.

Impact force uses an assumed effective striking mass (shin + foot, ≈2.5–3.5 kg depending on power/stance) and a short contact time (≈6 ms), consistent with the order of magnitude (hundreds to a few thousand newtons) measured in taekwondo kicking-force studies. It is an instructive estimate, not a cadaver-grade force plate reading.

Kicking leg Support leg / torso Target pad

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