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Technique Analysis
Forehand, backhand, serve, volley, footwork β get detailed breakdowns with biomechanical reasoning.
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Biomechanics
Kinetic chain, wave theory, tensegrity, proprioception β understand why techniques work.
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Pro Player Insights
Federer, Alcaraz, Sinner, Djokovic, Nadal, Shelton β learn from the world's best.
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Mental Game
Pre-performance routines, breathing, pressure management β train your mind as well as your body.
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Fitness & Injury Prevention
Age-appropriate training, proprioception programs, knee/back safety for 40+ players.
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Tactics & Strategy
70% rule, 3-shot patterns, serve & volley, doubles formations β game plans that work.
Sample Questions
How does Carlos Alcaraz generate so much power on his forehand?
Alcaraz's forehand is a masterclass in modern biomechanics. The key is his leg drive β he uses an exaggerated crouch in his unit turn to load his posterior chain, then explodes upward through ground reaction force. Combined with his "loop" forehand trajectory (high takeback, low finish) and a passive wrist (no active flexion), this lets him transfer energy from the ground through his kinetic chain in roughly 0.3 seconds. His forehand averages 78 mph with 2,500+ rpm topspin.
What is the kinetic chain and why does it matter?
The kinetic chain is the sequential transfer of energy from the ground, through your legs, hips, torso, shoulder, arm, and finally the racket. Each link "adds" rotational and linear velocity. For example, ground reaction force β hip rotation β torso coil β shoulder whip β arm lag β racket head speed. Studies show roughly 50% of racket head speed comes from the legs and core, only 30% from the arm. If you break the chain (e.g. by "arming" the ball), you lose power and increase injury risk.
I'm 52 and my knees hurt after playing. What should I do?
Three priority adjustments: (1) Stop doing deep squats with heavy load β replace with Bulgarian split squats and box squats to keep knees tracking over toes without compressive load. (2) Strengthen VMO (inner quad) and glute medius to stabilize patellar tracking. (3) On court, use a "tension-not-overload" rule: keep tension in your legs but never lock your knees β think "bridge by straight front leg" rather than "push off bent knee". Also consider switching to a softer court surface and using supportive tennis shoes with lateral stability.
Explain the 70% rule
The 70% Rule (popularized by Craig O'Shannessy) is the insight that professional tennis players only win ~54% of total points, but win ~70% of points when they are "in control" (defined as hitting a neutral or aggressive shot). The implication: don't try to win every point β focus on getting your opponent "on the run" or "in defense" first. The 70% rule is a tactical framework that emphasizes point construction over winner-hunting.
About Tennis Doctor
Built by: Henry PhαΊ‘m (PhαΊ‘m Δα»©c HαΊ£i), Vietnamese tennis coach and biomechanics researcher.
Knowledge base: 20,080 articles from his Obsidian vault + 97 tennis instruction books, covering technique, biomechanics, tactics, mental game, fitness, and pro player analysis. Original content is in Vietnamese; this English version uses LLM-translated excerpts and English-original notes.
Tech stack: Cloudflare Workers + Vectorize + Workers AI (free tier). Embeddings via BGE-M3 multilingual, generation via Llama 3.1 8B Instruct FP8.
Vietnamese version: Tennis WIKI (Vietnamese)