Variable BACK_KICK_ANIMATIONConst

Back Kick - 뒤차기 (Dwi Chagi) or 뒤후리기 (Dwi Hurigi)

Powerful spinning heel thrust - one of Taekwondo's most devastating techniques. 180° body rotation into linear heel strike - combines spin speed with thrust power.

Korean Martial Arts Biomechanics (한국 무술 생체역학):

Stance & Weight Distribution (자세와 체중 분배):

• Start: 겨루기 자세 (Fighting stance) facing target, 60/40
• Spin: Weight shifts during 180° rotation
• Thrust: 100% weight on supporting leg, back to target
• Recovery: Complete rotation, return to facing target
• Key: Blind technique - must look over shoulder!

Spin & Chamber Phase - 회전+준비 (Hoejeon + Junbi) [200ms]:

• Body rotation: 180° SPIN - turns BACK to target
• Head: Looks OVER SHOULDER at target throughout (critical!)
• Direction: Can spin either direction - usually toward back leg
• Supporting leg: Pivots on ball of foot during rotation
• Kicking leg: Lifts and CHAMBERS during spin
  • Hip flexion: ~90° (1.57 rad) as knee rises
  • Knee: Bent ~60° (1.05 rad) during chamber
• Hips: Rotate 180° to face AWAY from target
• Shoulders: Rotate with hips, back now to target
• Arms: 상단막기 (High guard) during spin - vulnerable moment!
• Eyes: NEVER lose sight of target - look over shoulder!
• Breathing: Inhale during spin (준비 호흡)
• Balance: Core engaged, smooth rotation
• Supporting foot: Pivots smoothly 180°

Thrust/Extension Phase - 차기 (Chagi) [300ms]:

• Leg: EXPLODES BACKWARD in straight line
• Knee: Extends from 60° → 170° (0.18 rad) - nearly straight
• Striking surface: 뒤꿈치 (heel) - hardest point
• Trajectory: STRAIGHT LINEAR backward thrust
• Hip: Drives BACKWARD through target - powerful thrust
• Ankle: PLANTARFLEXED (발목 펴기) - heel projects backward
• Body: Leans FORWARD ~15-20° to counterbalance
• Torso: Bent forward at waist, back parallel to ground
• Supporting leg: Straight 170° (0.18 rad), stable base
• Arms: Extended forward or high guard for balance
• Head: STILL looking over shoulder at target (critical visual!)
• Hip thrust: Drives kicking hip BACKWARD into strike
• Power: Linear backward thrust like mule kick!
• Breathing: Building to exhale

Peak Impact - 정점 (Jeongjeom) [120ms]:

• Maximum extension: Leg nearly straight 170° (0.18 rad)
• Impact: Heel DRIVES through target backward
• Target zones:
  • 명치 (solar plexus) - wind knockout
  • 늑골 (ribs) - rib fracture potential
  • 얼굴 (face) - knockout if aimed high
  • 무릎 (knee) - joint destruction if low
• Body lean: Maximum forward ~20-25° (like horse stance lean)
• Breathing: EXPLOSIVE exhale "차!" (Cha!) or "우억!" (Wueok!)
• Power delivery: Full body mass + spin momentum + thrust
• Supporting leg: Rock solid, no wobble
• Back to target: Completely vulnerable - must land kick!
• Eyes: Target locked through side vision
• Follow-through: Hip continues backward past initial contact

Recovery/Complete Rotation - 복귀/회전완성 (Bokgwi/Hoejeon Wanseong) [380ms]:

• Leg: Retracts from extension, pulls back
• Body: CONTINUES rotation to complete 360° total (or stops at 180°)
• Two options:
  1. Complete spin (360° total): Continue rotation to face target again
  2. Reverse spin (180° back): Reverse spin to face target
• Typical: Complete the spin (forward momentum)
• Head: Rotates to acquire target visually again
• Foot: Lowers to ground facing target (forward position typical)
• Supporting leg: Completes pivot
• Weight: Shifts from 100% → 60/40 distribution
• Hips: Square back to target (정면 - Jeongmyeon)
• Arms: Return to 중단막기 (middle guard)
• Stance: Reset to 겨루기 자세 (fighting ready)
• Breathing: Controlled recovery
• Balance: Smooth completion, no stumbling

Combat Applications (전투 응용):

• Counter technique: Spin AWAY from attack, back kick stops it
• Surprise attack: Unexpected rotation confuses opponent
• Power strike: Combines spin momentum + linear thrust = devastating
• Target selection:
  • Body: 명치 (solar plexus), 늑골 (ribs) - most reliable
  • Head: High back kick - spectacular knockout
  • Knee: Low back kick - mobility destruction
• Combinations:
  • 돌려차기-뒤차기 (Roundhouse-Back kick) - spin combo
  • 뒤차기-돌려차기 (Back-Roundhouse) - continue spin
  • 옆차기-뒤차기 (Side-Back kick) - lateral to rear

Biomechanical Keys (생체역학 핵심):

1. 180° spin = Enables backward thrust (must turn back!)
2. Look over shoulder = Visual targeting (no look = no hit!)
3. Linear thrust = Maximum backward power
4. Heel strike = Concentrated force, bone-on-bone
5. Forward lean = Counterbalance enables full extension
6. Spin momentum = Adds rotational energy to linear thrust

Physics Principle: "회전 운동량이 직선 충격으로 변한다" (Rotational momentum converts to linear impact)

• Spin angular velocity → Leg linear velocity
• Rotational KE + Thrust KE = Devastating combined force
• Heel = Point force = Maximum PSI
• Backward thrust = Mule kick biomechanics

Taekwondo Principle: "뒤차기는 태권도의 용기다" (Back kick is the courage of Taekwondo)

• Most risky: Turn your back = ultimate vulnerability
• Most powerful: Spin + thrust = maximum force
• Most surprising: Unexpected rotation and strike
• Most committed: No retreat - must land or fail

Common Mistakes (흔한 실수):

• ❌ No shoulder look (안 쳐다보기) - BLIND kick will miss!
• ❌ Bent leg thrust (구부린 다리) - Power leak
• ❌ Upright body (똑바로 서기) - Can't extend fully
• ❌ Slow spin (느린 회전) - Telegraphed, countered
• ❌ Incomplete rotation (불완전 회전) - Awkward angle
• ❌ Pointed toes (발끝 펴기) - Wrong striking surface
• ✅ Correct: Fast spin + shoulder look + forward lean + heel thrust

Training Points (훈련 포인트):

• Shoulder look critical: Practice looking back during spin
• Spin speed: Faster spin = more power and less telegraphing
• Balance: Single-leg balance while rotated backward
• Forward lean: Must lean to extend fully - practice against wall
• Landing: Complete rotation smoothly without stumbling

Competition vs. Street (겨루기 vs. 실전):

• Competition: Spectacular scoring technique, high-risk/high-reward
• Street: VERY risky - turning back = vulnerable
• Best when: Opponent charging - spin and stop them cold
• Avoid when: Multiple opponents - never turn back!

Risk Assessment (위험 평가):

• ⚠️ Turning back = Temporary blindness
• ⚠️ Spin time = Vulnerable moment
• ⚠️ If miss = Back still to opponent = bad position
• ✅ If land = Devastating power ends fight

Breathing Pattern (호흡 패턴):

• Spin/Chamber: Inhale during rotation (회전중 들이마시기)
• Thrust: Hold breath during acceleration (추진중 호흡 유지)
• Impact: Explosive 기합 (Kihap) "차!" or "우억!"
• Recovery: Controlled recovery breath while completing rotation

Total duration: 1000ms (HEAVY technique)