Straight Knee Kho Drong Muay Thai
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Straight Knee·Fight Vision - Muay Thai - Thai Boxing
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Straight Knee
Family直膝蹴り(Choku Hiza-geri)
TraditionalTranslation: straight knee
Overview
History & Origin
The straight knee is the most fundamental knee strike in Muay Thai, delivered in a direct upward or forward trajectory into the opponent's body or head. [1] Kraitus and Rennehan identify the straight knee as the first knee technique taught to Muay Thai students, forming the foundation of all other knee variations. [1] In Muay Boran, the straight knee was one of the 'mae mai' (master techniques) — core movements from which more advanced techniques were derived. [2] The straight knee was also preserved in Japanese karate as hiza-geri (knee kick), documented by Nakayama in Dynamic Karate as a close-range self-defence technique. [3]
Effectiveness
Lineage
From Muay Thai's khao trong. [1]
Competition Record
The most commonly thrown knee in Muay Thai and MMA. [1]
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Biomechanical Mechanism
Primary Action — Driving the knee upward or diagonally into the target using hip flexion and body weight
Joints Involved — Hip (powerful flexion drive), knee (point of impact, flexed), core (posture and power transfer)
Force Vector — Upward (straight knee to body/head), diagonal (round knee from the side), or clinch-pull driven
Clinch Integration — Most effective when combined with clinch control — pulling the opponent's head down into the rising knee multiplies impact force
Position & Entry
From orthodox stance (after jab) — Rotate the rear hip forward, extend the rear hand straight to the target, pivot the rear foot
As counter (pull counter) — Lean back to avoid the incoming jab, fire the cross as the opponent's jab retracts
From clinch break — Push off from the clinch, create space, and fire the straight right as the opponent resets
Videos
1 video
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Ratings
Risk of injury to the person this technique is applied to
7
Very High7/10
Muay Thai khao trong; direct upward thrust to body/head
Skill level needed to execute this technique reliably
Beginner
Whether this technique is allowed under major competition rule sets
Illegal
WBC/Boxing — All knee strikes prohibited {src— WBC Rules of Boxing}
— WKF — Prohibited in sport karate
WKF Competition Rules 2024PDF— WT — Prohibited
WT Competition Rules 2024PDF— ITF — Prohibited
ITF Competition RulesPDF— WAKO — Prohibited in most formats
WAKO Competition RulesPDFRestricted
— Unified MMA — Knees to standing opponent legal, knees to ...
Unified Rules of MMA, August 2025PDFK-1/GLORY — One clinch knee allowed before referee break {src— K-1/GLORY Kickboxing Rules}
Legal
Kyokushin — Legal to body {src— IKO Kyokushin Tournament Rules}
— IFMA — Legal — knees are a core Muay Thai weapon, clinch ...
IFMA Muay Thai RulesPDFTraining Notes
✓The straight knee drives directly upward into the opponent's body or chin in a vertical line
✓The power comes from hip extension and an upward drive from the support leg
✓The straight knee is the most common and fundamental knee strike in Muay Thai
✓From the clinch, pull the opponent's head down while driving the knee straight up into the solar plexus or face
✓Rise onto the ball of the support foot at the moment of impact to add height and hip extension
✓The straight knee is the highest-force knee strike because the entire body drives upward behind it
✓Drill the straight knee by driving it into a heavy bag or belly pad, focusing on hip extension at the top of the motion
Common Mistakes
!Not driving the hip through the knee — the hip must extend fully, pushing the knee through the target
!Bumping the knee into the opponent instead of driving upward through them
!Not pulling the opponent into the knee from the clinch — the collision of forces is critical
!Flat-footed support leg, which limits the height and power of the upward drive
!Leaning back too far as compensation for lack of hip drive
!Throwing single knees without follow-up — string them together or combine with elbows
!Not controlling the opponent's posture — the straight knee works best when they are bent forward into the strike
Related Techniques
Counter Techniques
Setup Chain
1Fighting Stance — begin from a balanced stance with hands protecting the chin
2Weight Transfer — shift weight from rear to lead foot (jab) or rotate hips (cross)
3Extend — drive the fist straight toward the target along the centre line
4Snap Back — retract the hand quickly to defensive position
Sources & References
Primary Source
Muay Thai: The Art of Fighting (Yod Ruerngsa, Khun Kao Charuad & James Cartmell, 2002)
1BookMuay Thai: The Art of Fighting (Kraitus, 2002)
Alias sources — [1] Muay Thai: The Art of Fighting (Kraitus & Kraitus, 1988) [2] Dynamic Karate (Nakayama, 1966)
2BookMuay Thai Unleashed (Delp, 2006)
History sources — [1] Muay Thai: The Art of Fighting (Kraitus & Rennehan, 2002) [2] Muay Boran: The Ancient Art of Muay Thai (Rebac, 2008) [3] Dynamic Karate (Nakayama, 1966)
Official karate technique names (和語/漢語)
4OtherJapanese Martial Arts Standard Terminology (武道用語)
Established Japanese martial arts naming convention — native Japanese term (和語/漢語)
5CitationMuay Thai: The Art of Fighting (Kraitus, 2002)
Alias sources — [1] Muay Thai: The Art of Fighting (Kraitus & Kraitus, 1988) [2] Dynamic Karate (Nakayama, 1966)
6CitationMuay Thai Unleashed (Delp, 2006)
History sources — [1] Muay Thai: The Art of Fighting (Kraitus & Rennehan, 2002) [2] Muay Boran: The Ancient Art of Muay Thai (Rebac, 2008) [3] Dynamic Karate (Nakayama, 1966)
Community
Athletics
Requires
hip flexion power, clinch control ability, close-range comfort
Favours
long thigh for greater leverage, strong hip flexors
Key muscles
hip flexors, quadriceps, core, grip (for clinch)
Sub-techniques
Clinch Knee
SubFamilyA straight knee strike delivered from within the clinch, using collar ties and head control to pull the opponent into the rising knee.
1 genera·1 techniquesExplore
Distance Knee
SubFamilyA straight knee strike delivered from outside clinch range, stepping or lunging forward to close the distance and drive the knee into the target.
1 genera·1 techniquesExplore
Notes
The straight knee (khao trong in Muay Thai) is delivered in a forward thrust from the clinch. It targets the body, face, or thigh of the opponent. Muay Thai clinch knees are one of the most damaging close-range weapons. (Delp, Muay Thai Unleashed; Kraitus, Muay Thai: The Art of Fighting)
Frequently Asked Questions
How do I generate power in a straight knee strike?
Drive your hips forward as you execute the knee—the hip drive is essential to generating power in the straight knee. Fight Vision emphasizes that proper hip engagement is what makes the technique effective.
What footwork should I use before throwing a straight knee?
Step forward with one foot to close distance and set up your balance before driving the knee straight up. This stepping motion helps you generate momentum and stability for the strike.
Can I throw a straight knee off a hand parry?
Yes—you can parry an incoming strike with your hand and immediately step and drive a straight knee as a counter-attack in the same combination.
How does the Straight Knee work?
A knee strike driven directly upward or forward in a linear path, typically targeting the midsection, solar plexus, or face.
Where does the Straight Knee come from?
The straight knee is the most fundamental knee strike in Muay Thai, delivered in a direct upward or forward trajectory into the opponent's body or head. Kraitus and Rennehan identify the straight knee as the first knee technique taught to Muay Thai students, forming the foundation of all other knee variations.
Is the Straight Knee legal in competition?
Unified MMA: restricted — Knees to standing opponent legal, knees to head of grounded opponent banned; WBC/Boxing: banned — All knee strikes prohibited; WKF: banned — Prohibited in sport karate; Kyokushin: legal — Legal to body; WT: banned — Prohibited; ITF: banned — Prohibited; WAKO: banned — Prohibited in most formats; K: restricted — 1/GLORY — One clinch knee allowed before referee break; IFMA: legal — Legal — knees are a core Muay Thai weapon, clinch knees highly scored
How dangerous is the Straight Knee?
Danger rating 7/10. Very High — Muay Thai khao trong; direct upward thrust to body/head
How do I set up the Straight Knee?
The standard setup chain: Fighting Stance → Weight Transfer → Extend → Snap Back.
How do I defend against the Straight Knee?
Standard counters include: Hip Check — push the opponent's hips away to create distance and kill the knee angle / Clinch Control — control the opponent's head and posture to prevent knee generation / Step Back — create distance to escape the knee's effective range.
What are the variants of the Straight Knee?
Common variants: Straight knee (driving the knee straight upward into the body or head); Curved knee (round knee) (swinging the knee from the side in a circular path); Flying knee (leaping forward and driving the knee at the apex of the jump); Clinch knee (pulling the opponent into the knee from Muay Thai plum po…).
How effective is the Straight Knee in competition?
The most commonly thrown knee in Muay Thai and MMA.
What are common mistakes when doing the Straight Knee?
Top errors to watch for: Not driving the hip through the knee — the hip must extend fully, pushing the knee through the target / Bumping the knee into the opponent instead of driving upward through them / Not pulling the opponent into the knee from the clinch — the collision of forces is critical / Flat-footed support leg, which limits the height and power of the upward drive.
What are other names for the Straight Knee?
The Straight Knee is also known as Choku Hiza-geri, Khao Trong, Hiza Geri.