A knee strike is a strike

Strike (attack)

A strike is an attack with an inanimate object, such as a weapon, or with a part of the human body intended to cause an effect upon an opponent or to simply cause harm to an opponent. There are many different varieties of strikes...

 with the knee

Knee

The knee joint joins the thigh with the leg and consists of two articulations: one between the fibula and tibia, and one between the femur and patella. It is the largest joint in the human body and is very complicated. The knee is a mobile trocho-ginglymus , which permits flexion and extension as...

, either with the kneecap or the surrounding area. Kneeing is a disallowed practice in many combat sports, especially to the head of a downed opponent

Downed opponent

A downed opponent is a combatant that is on the ground, as compared to a combatant that is in a standing position. This commonly implies that the downed combatant is lying on the ground, but can technically refer to any position in which anything except the soles of the combatants feet are...

. Styles such as Muay Thai

Muay Thai

Muay Thai is a combat sport from Thailand that uses stand-up striking along with various clinching techniques. It is similar to other Indochinese kickboxing systems, namely pradal serey from Cambodia, tomoi from Malaysia, lethwei from Myanmar and muay Lao from Laos...

 and several mixed martial arts

Mixed martial arts

Mixed Martial Arts is a full contact combat sport that allows the use of both striking and grappling techniques, both standing and on the ground, including boxing, wrestling, Brazilian jiu-jitsu, muay Thai, kickboxing, karate, judo and other styles. The roots of modern mixed martial arts can be...

 organizations allow kneeing depending on the positioning

Grappling position

A grappling position refers to the positioning and holds of combatants engaged in grappling. Combatants are said to be in a neutral position if neither is in a more favourable position. If one party has a clear advantage such as in the mount they are said to be in a "dominant position"...

 of the fighters.

Straight

The straight knee (also known as a front knee) is a typical knee strike, and involves thrusting the front of the knee into the head or body of an opponent. The straight knee can be applied from a stand-up position both when the combatants are separated, or when they are clinching. A particularly effective clinching position for throwing front knee is the double collar tie, where the head of the opponent is controlled. On the ground, front knees can be effective from a few top positions such as the Side control

Side control

Side control is a dominant ground grappling position where the top combatant is lying perpendicularly over the face-up bottom combatant in such a way that the legs are free and he or she exerts considerable control over the combatant on the bottom...

 and north-south position

North-south position

In combat sports, the north–south position is a ground grappling position where one combatant is supine, with the other combatant invertedly lying prone on top, normally with his or her head over the bottom combatant's chest...

. Typical targets for the front knee include the head, hips, rib

Rib

In vertebrate anatomy, ribs are the long curved bones which form the rib cage. In most vertebrates, ribs surround the chest, enabling the lungs to expand and thus facilitate breathing by expanding the chest cavity. They serve to protect the lungs, heart, and other internal organs of the thorax...

s, solar plexus, stomach

Stomach

The stomach is a muscular, hollow, dilated part of the alimentary canal which functions as an important organ of the digestive tract in some animals, including vertebrates, echinoderms, insects , and molluscs. It is involved in the second phase of digestion, following mastication .The stomach is...

 and thigh

Thigh

In humans the thigh is the area between the pelvis and the knee. Anatomically, it is part of the lower limb.The single bone in the thigh is called the femur...

s. In Muay Thai, a double collar tie with a front knee to the face was traditionally called Hak Kor Aiyara. The groin is widely considered the key target for knee strikes and clinch knee attacks in a street fight according to karate, tae kwon do, mauy thai, and many other martial arts.

Curved

The curve knee (also sometimes called a side knee) is similar to the front knee except that it does not use a forward thrusting motion, but is instead rotated from the outside. Whereas the front knee needs some space in between the combatants to be performed, the curved knee can be executed from a minimal distance, such as in a close clinch. Typical targets include floating ribs, hips

Hip (anatomy)

In vertebrate anatomy, hip refer to either an anatomical region or a joint.The hip region is located lateral to the gluteal region , inferior to the iliac crest, and overlying the greater trochanter of the femur, or "thigh bone"...

, and the side of the abdomen

Abdomen

In vertebrates such as mammals the abdomen constitutes the part of the body between the thorax and pelvis. The region enclosed by the abdomen is termed the abdominal cavity...

.

Flying

A flying knee (known as hanuman thayarn in Muay Thai

Muay Thai

Muay Thai is a combat sport from Thailand that uses stand-up striking along with various clinching techniques. It is similar to other Indochinese kickboxing systems, namely pradal serey from Cambodia, tomoi from Malaysia, lethwei from Myanmar and muay Lao from Laos...

, and sometimes called a jumping knee) is a knee strike very similar to a front knee, except that it is performed in stand-up fighting

Stand-up fighting

Stand-up fighting is hand-to-hand combat that takes place while the combatants are in a standing position. The term is commonly used in martial arts and combat sports to designate the set of techniques employed from a standing position, as opposed to techniques employed in ground fighting...

 by jumping, and often by rushing towards the opponent. A more reckless application of the flying knee strike can be applied by rotating the body so that the side of the knee strikes the opponent, used more as an offensive pushing attack rather than a concussive KO attack. Generally, flying knee strikes can be effectively applied when the opponent is off-balanced, recovering from previous strikes, or as a counter to a strike by the opponent. It can also be used as a follow-up maneuver after delivering a particularly incapacitating strike. One such example of this was at a UFC event where David Loiseau

David Loiseau

David Loiseau is a Canadian mixed martial artist from Montreal, Quebec. He has fought in the Ultimate Fighting Championship, EliteXC, and TKO Major League MMA and is the former TKO Middleweight Champion. He was the first French Canadian to fight in the Ultimate Fighting Championship...

, after buckling his opponent Charles McCarthy with a Tae Kwon Do technique, a Jump Back Kick, to the abdomen, immediately charged in with a flying knee, knocking McCarthy down against the cage and finishing the fight via technical knockout

Use in combat sports

Provided that it makes impact with the head, a flying knee offers substantial momentum and knockout power. This spectacular strike is a crowd-pleaser in fighting sports such as K-1

K-1

K-1 is a defunct world-wide kickboxing promotion based in Tokyo, Japan founded by Kazuyoshi Ishii, a formerKyokushin karate practitioner. K-1 combines stand up techniques from Muay Thai, Karate, Taekwondo, Savate, San Shou, kickboxing, western-style boxing, and other martial arts...

(KickBoxing) and MMA. In one UFC bout, James Irvin

James Irvin (fighter)

James Lee Irvin is an American mixed martial artist who has competed as a Middleweight, Light Heavyweight, and currently as a Heavyweight. He is a former World Extreme Cagefighting heavyweight champion...

 knocked out Terry Martin

Terry Martin (fighter)

Terry Martin is an American mixed martial artist from Chicago, Illinois.Martin made his professional boxing debut on April 12, 2008, and defeated Ricardo Upchurch by knockout in 40 seconds. Martin won his next three bouts via knockout or technical knockout.- Early life :Martin grew up on the west...

 with a flying knee; Martin was unresponsive for three minutes and left on a stretcher. At K-1 Hero's 5

HERO'S

Hero's was a Japanese mixed martial arts promotion operated by Fighting and Entertainment Group, the parent entity behind kickboxing organization K-1. Grown from and branched off of K-1's earlier experiments in MMA, including the K-1 Romanex event and various MMA fights on its regular K-1...

, Norifumi Yamamoto

Norifumi Yamamoto

is a Japanese mixed martial artist and kickboxer. He is associated with Purebred Tokyo and Krazy Bee. He quickly gained popularity in the Shooto organization due to his aggressive, well-rounded style and controversial persona...

 knocked out Kazuyuki Miyata with a flying knee at four seconds into the first round. Kickboxer Remy Bonjasky

Remy Bonjasky

Remy "The Flying Gentleman" Bonjasky is a Dutch super heavyweight kickboxer of Surinamese descent. He is a three-time K-1 World Grand Prix champion, who has won the title in 2003, 2004, and 2008...

 is known for his flying knees.. Japanese professional wrestling, in keeping with its martial arts

Martial arts

Martial arts are extensive systems of codified practices and traditions of combat, practiced for a variety of reasons, including self-defense, competition, physical health and fitness, as well as mental and spiritual development....

 roots, has many wrestlers utilizing knees in matches. Tomomi Tsuruta also used a jumping knee as one of his finishing moves. Takashi Sugiura

Takashi Sugiura

is a Japanese professional wrestler, currently working for Pro Wrestling Noah. Sugiura, an accomplished amateur wrestler, joined NOAH's dojo in 2000, making his professional debut on December 23, 2000, and thus becoming the first wrestler to make his pro wrestling debut in NOAH. He has also...

 and Jun Akiyama

Jun Akiyama

is a Japanese professional wrestler who currently works for Pro Wrestling Noah and All Japan Pro Wrestling, where he is the current AJPW Triple Crown Heavyweight Champion. Akiyama is known for his serious style and outstanding, time-tested work as a tag team wrestler...

 are known for their effective knee strikes. José Aldo

Jose Aldo

José Aldo is a Brazilian mixed martial artist, who competes as a featherweight in the Ultimate Fighting Championship where he is the first and current UFC Featherweight Champion...

 landed a double flying knee at WEC 41

WEC 41

WEC 41: Brown vs. Faber 2 was a mixed martial arts event held by World Extreme Cagefighting on June 7, 2009 at the Arco Arena in Sacramento, California. It was the most successful show in the WEC's history....

 against Cub Swanson

Cub Swanson

Kevin Luke Swanson is an American mixed martial artist . He is currently signed as a featherweight with the Ultimate Fighting Championship.-World Extreme Cagefighting:...

, in one of his first international MMA fights, scoring a knockout win just eight seconds into the first round of the fight.