Is Karate Kid Correct About Martial Arts and Aggression?

When The Karate Kid came out in 1984, I was a teen in my own karate training. I got hooked on the premise of that and the following movies, and I have to admit that I'm a fan of the TV series Cobra Kai. A lot of what happens in the movies and series resonates with me since my initial years were heavily based on sports karate, and tournament competition. The '80s were also a big part of my learning to enjoy hair metal and heavy metal music, which forms a large part of the soundtrack to the current Netflix show.

Cobra Kai Chaos or Karate Kid Kindness?

One of the things that I don't appreciate about some aspects of the movies, but mainly the Cobra Series, is the way it depicts unbridled aggression in the young kids who are taking martial arts. Although originally this was shown mostly in Cobra Kai, it bleeds into Miyagi-do and everything else you see. Especially when you arrive at the final season of the current Netflix show, and the admittedly entertaining, but egregious violence and mayhem.

This goes against my experience training in martial arts at a young age, teaching martial arts to kids and teens, and many anecdotal stories from others. Yet there has been relatively less empirical evidence about the effect of martial arts on aggression, particularly in adolescents. This is why a recent study from China caught my interest.

Self-Control in Kung Fu and Karate Kids?

Researcher Ting Xu, Hansen Li, Ge Rao and Feng Wang from Xinjiang, Chongqing, and Sichuan in China and from Bangkok, Thailand, have an interest in factors related to violence and school bullying. They set out to study what effect martial arts training might have on aggression in adolescents and recently published their work in the journal BMC Psychology. They were especially interested in understanding the "roles of self-control and depression in mediating the relationship between martial arts participation and aggression."

They surveyed a very large group of almost 850 participants (average age 13 years; grades 7 to 9) who trained in martial arts with an almost even split of those identifying as male or female. Also, approximately half the participants did traditional Chinese martial arts, and the others did other systems like Taekwondo and kickboxing. Folks in the study "completed the Physical Activity Rating Scale, Self-Control Scale, Depression Scale, and Aggression Scale."

The results showed that martial arts "exercise level negatively predicted aggression," meaning the more they did, the less aggressive they were. Also, there wasn't any difference in the effects you might get from Chinese compared with other martial arts. Interestingly, the pathways by which the moderation of aggression unfolded were heavily linked with effects on self-control.

The key outcomes are nicely summarized by the authors, suggesting that martial arts training "is a potential strategy for reducing aggression and psychological distress while enhancing self-control. Educators and martial arts organizations should emphasize both technical training and ethical instruction to foster self-regulation and emotional well-being in adolescents. Moreover, increasing martial arts training intensity may further amplify these benefits."

All these years later, it's still an illegal kick

There's a clear alignment between the experiences many folks have in learning and teaching traditional martial arts and the research literature that supports the idea that such training can help enable better self-control, a calmer mindset, and less aggression. We're going to have to come down on the opposite side of the fence on what we see in Cobra Kai and suggest that the contrasting trend should have been happening throughout the show. This resonates with a key karate concept espoused by Gichin Funakoshi (1868-1957; founder of Shotokan) that "karate without courtesy is violence."

This overall perspective does parallel the character development arc that so many of the folks on Cobra Kai experienced, including Daniel and Johnny, and in the films, including the most recent Karate Kid Legends. Everyone seems to have a turn at being both bully and bullied, but at the very end of the journey, they do typically demonstrate better self-control and enhanced empathy.

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I have one final thing to say about the original Karate Kid movie that got this whole franchise going. For sure I'm firmly on the side of Johnny Lawrence and this is from both the actual rules and from the perspective of someone who was kicked in the face by a similar technique in a tournament more than 40 years ago: that last move that Daniel-san used to win the All Valley Tournament was definitely an illegal kick.

(C) E. Paul Zehr (2025)