Straight Knee
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The straight knee drives the point of the knee upward into the body, most often the solar plexus, floating ribs or the inside of the thigh. It is the shortest-range power technique legal in kickboxing, and its availability is one of the cleanest dividing lines between the codes: legal under K-1, GLORY, ONE, Dutch and WAKO K-1 rules, illegal under every American full-contact and low-kick variant, illegal in savate, and restricted to the body under Sanda and Kyokushin.
The motion is a hip extension, not a leg lift. The knee travels up as the hips drive forward and the torso leans slightly back to counterbalance; a knee thrown by lifting the thigh alone has almost no mass behind it. Hands either post on the opponent's shoulders to create the frame, or grip behind the head in a collar tie, depending on what the ruleset allows in the moment before the referee separates.
In K-1-derived rules the knee lives in a very narrow window. The clinch is broken almost immediately, so a fighter gets one — sometimes two — before the referee steps in. That constraint has shaped how the technique is used in modern kickboxing: rather than the sustained clinch attrition of Muay Thai, the knee is a single decisive strike thrown in the instant the hands connect, or thrown from open range as an interception against someone coming forward.
Key points
- Drive with the hips rather than lifting with the thigh — the extension is the power
- Lean the torso back slightly to counterbalance and open the hip
- Point the knee and strike with the point, not the flat of the thigh
- Under K-1-derived rules, expect one strike before the referee breaks — make it count
- Post or frame on the shoulders if the clinch is not yet established
- Under Sanda and Kyokushin, target the body only
Common mistakes
- Lifting the knee without extending the hips, which produces a soft, pushing knee
- Standing straight up, which cancels the hip drive
- Holding for the second and third knee under rules that only permit the first
- Throwing it at an opponent who is out of range, which leaves the leg hanging
- Neglecting the frame, so the opponent simply steps back out of the knee
Drills
- 1Belly-pad rounds emphasising hip extension, with a partner calling for single knees on contact
- 2Clinch-break drill: establish grip, land one knee, separate — matching the K-1 rules window
- 3Interception drill: partner steps forward and the fighter meets them with a straight knee from open range
- 4Bag work with the hands posted high to build the frame-and-knee coordination