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Kicking & the Hips

Joshua Hodges


Hips Socket


The emphasis on proper technique in Shotokan karate produces powerful and effective results.  Through studying kinesiology, we have learned the proper body dynamics for using our bodies as effective weapons.  Although karate is not science, there is science behind the movements that we make.  The forces generated by effective techniques can deliver punishing, even lethal, blows.   However the forces delivered from techniques performed improperly not only are less effective on opponents, but may cause injury to the practitioner.


One phrase that you will hear time and time again in the dojo is “use your hips.”  It is very important to rotate from your hips to create powerful kicks, punches, strikes, and blocks.  The hip joint can basically be thought of as a ball in a socket.  In the above illustration, you can see that the femoral ball projects at an angle to the length of the thigh bone. It fits in the hip socket or acetabulum, which is part of the construction of the pelvis.  It is lubricated with synovial fluids inside the joint, which is lined with a smooth cartilage. Because of the ball in socket construction, this joint may articulate in many directions.  It may rotate externally or internally.  It may also slightly extend acting as a shock absorber for walking.  It may be flexion, drawing the knee up and the thigh closer to the torso, as in mae geri.  It may also be abducted and adducted moving laterally out from the body and back towards the body’s centerline as in yoko geri keage.


Recently I watched the video Stan Schmidt Instructs Shotokan Karate Vol. 3. When speaking on the importance of the pendulum motion associated with the front kick, Sensei Schmidt describes a slight rocking forward of the pelvis. If this crucial motion is not part of the kick, he states that the “femoral head banging up” could lead to hip joint damage.  For side snapping kick, he also warns that improper technique could lead to a similar injury when articulating the hip laterally. Sensei Schmidt stated that the side snap kick can be terribly dangerous if the hip doesn’t move first in the direction of the kick. To do this kick properly and safely, he demonstrates a tilting up of the hip after the leg is chambered, prior to snapping out the kick. He again warns of the femoral head banging into the hip socket if this tilt is not part of the motion of the kick.


In both instances he warns of the possibility of grinding the bone in the joint. By incorporating the pendulum motion in the front kick, the joint is free to move without obstruction. Similarly, leading with the hip by tilting the hip up in a side kick frees the joint so that no grinding of the bone occurs.


It turns out that karate-ka have a high incident of hip injuries. A study conducted by researchers from the University of Bern in Switzerland used MRI images of 97 hips of karate competitors to examine structural changes. They also subjected the participants of the study to range of motion and impingement tests. Their goal was to look at the effects karate training had on the onset of osteoarthritis, the wearing of the cartilage inside the joint.


The results showed that the age of the fighter did not show a relationship with the results yielding the amount of hip damage. “But the more years of karate training, the more labral lesions and the more cartilage damage was found. And the earlier the athlete started the training, the higher was the prevalence of an increased alpha angle, labral lesions, and cartilage damage,” states Inge Kress, a student from the University of Bern, Switzerland.

Some of the results:


·         15 percent of the hips examined showed normal cartilage, 78 percent had degenerated cartilage, and seven percent had full thickness defects.


·         The mean alpha angle of 64.3 degrees was found in the hips of the karate fighters. Any angle greater than 55 degrees is considered abnormal.


·         Forty-eight out of the 97 hips had a degenerated labrum, 33 had a torn labrum and only 16 were normal.


·         The MRIs found herniation pits, cysts, and mycoid degeneration, thus indicating much stress in the hip joint.


I spoke to orthopedic surgeon and karate champion, Dr. Derek Ochiai of Arlington Virginia.  He states that in his practice, FAI (femoroacetabular impingement) is a common condition where the femoral head is "out of round" and with flexion/internal rotation, can impinge upon the labrum (gasket cartilage surrounding the hip). With damage to this structure, the acetabular articular cartilage (smooth cartilage inside the joint) is also attacked, which can lead to hip arthritis. 


Dr. Ochiai and Sensei Schmidt seem to be talking about the same thing regarding the grinding of the femoral head inside the joint.  By using the pendulum action of the hip in mae geri and a tilting of the hip when performing yoko geri keage this effect can be minimized. The motion of the pelvis, whether in front kick or snap kick, also affects the joint of the support leg. While this hip motion may free up joint mobility in the kicking leg, in rare cases it could lead to impingement of the joint in the support leg.  However, the stress to the joint of the support leg is minimal when compared to the kicking leg.


Higher kicks also lead to a greater chance of impingement inside the hip joint. Not everyone’s hips and ligaments are developed that they can perform high kicks. Dr. Ochiai states that, “Listening to one's body is important. Some people's hips are just not designed for high kicks (FAI), and you can stretch all you want, but a bony impingement will remain.” In the same video, Sensei Schmidt also reminds the viewer that Funikoshi Sensei only advocated lower level kicks.  It is always better to perform a lower level kick correctly then to throw a high kick without proper mechanics.


So what of the study that basically says the longer you participate in karate the more of a risk you run in wrecking your hips?  Dr. Ochiai puts it in perspective:


As with ANY strenuous activity, there are risks and benefits. While I see some martial artists with hip labral tears and FAI, it is a small proportion compared to soccer, lacrosse, football, baseball, and basketball. I would be hesitant to make a direct comparison, as martial arts is one of the few sports that one can maintain at a relatively high level even as one gets significantly older (so is the karate causing the hip arthritis, or is it just that more people can be active in karate than professional football?).


With the seriousness of this type of injury, it is all the more important that you pay proper attention to your body dynamics, your alignment, and posture.  Use your hips, but use them properly.  Listen to your body, and don’t put off going to the doctor if something feels out of whack.  Ibuprofen and icepacks are great, but if they are becoming a routine part of training, it might be time to seek medical advice.


Joshua Hodges