BJJ and bullying: what the studies actually say

What has actually been measured

An Australian randomised trial (Moore, Woodcock and Dudley, *IJERPH*, 2019) followed 283 students aged 12 to 14: half did ten fifty-minute taekwondo sessions combined with psycho-education on respect, goal-setting, resilience and bullying. Results: resilience and self-efficacy improved significantly in the training group, and declined in the control group. On emotional and behavioural problems, no effect at all.

The limitation is the authors' own, and it's the one that matters: you can't separate the effect of the martial art from the effect of the psycho-education. Ten fifty-minute sessions with a psychologist and an instructor are not "a martial arts class".

An American study of 254 children in grades three to five (Twemlow and colleagues, *Psychology in the Schools*, 2008) evaluated a school programme built on traditional martial arts. Among boys who attended more, aggressive behaviour was lower and *helpful bystanding* higher — stepping in for the child being targeted instead of watching — with empathy acting as the mediating mechanism. For girls, no significant results. It was not a randomised trial.

And when you pool the studies?

Here it gets complicated, instructively so.

A 2025 meta-analysis (Luo and colleagues, *Adolescent Research Review*) across 16 randomised trials finds prosocial behaviour up and aggression down, with a recurring dose: programmes of twelve to sixteen weeks.

But a 2026 systematic review (Deng, Ma and Luo, *Frontiers in Public Health*) covering 11 longitudinal studies and 1,352 young people aged 8 to 18 — jiu-jitsu included — concludes that there is no consistent directional effect on aggression: some studies see it fall, others see it rise, many see nothing. What seems to move the needle isn't the style practised but how it's taught: programmes built on discipline, etiquette and moral education show better outcomes than competition-centred ones.

The hole in the data

There's one thing none of these studies measure: whether the child stops being targeted. The measured outcomes are aggression, prosocial behaviour, resilience and self-efficacy — all of them about the child doing the training. Nobody has followed a group of bullied children to see whether, after a year on the mats, the bullying directed at them went down.

So the honest answer to "if I sign him up, will they stop?" is: we don't know, and anyone guaranteeing otherwise is selling, not citing.

What does change, and the data doesn't capture

This part isn't measured by any study — it's shared observation from people who teach children, and we give it as exactly that. A child who has been grappling for a few months changes three things: they stop stiffening up when someone is on top of them, because it happens every week; they know that ending up on the ground isn't the end, which is precisely the fear physical bullying leans on; and they carry themselves differently, which matters more than it sounds when someone is picking who to target.

None of those three is "knowing how to fight back". There is no striking in jiu-jitsu, and the most useful thing a child learns is staying calm while something unpleasant is happening.

What parents get wrong most often

Assuming the problem is physical. Most bullying isn't: it's exclusion, mockery, messages, isolation. Against those, knowing an armbar is worth nothing — and responding physically almost always makes the child's position worse, at school and in front of adults.

The mats can give your child calm and confidence. They don't replace talking to the school, and they don't replace talking to him. If something is going on right now, the gym is something to add, not something to do instead.

What to ask a gym

• How sparring pairs are made: a small child put with a much bigger one only learns to endure.
• What happens if a child uses what they learn to throw their weight around — is there a stated rule, or is it improvised?
• How the room is supervised: how many adults for how many children.
• Whether the instructor has experience with children, or teaches adults and "does the little ones too".

Sources: Moore B., Woodcock S., Dudley D., *Developing Wellbeing Through a Randomised Controlled Trial of a Martial Arts Based Intervention*, IJERPH, 2019; Twemlow S. W. et al., *Effects of participation in a martial arts–based antibullying program in elementary schools*, Psychology in the Schools, 2008; Luo et al., *Effects of Martial Arts Exercise on Children's Prosocial and Aggressive Behaviors*, Adolescent Research Review, 2025; Deng, Ma, Luo, *Martial arts training and aggressive behavior in children and adolescents*, Frontiers in Public Health, 2026. On self-defence in general, held to the same standard: what the data actually says.