“A lot of people, when they think self-defence, they think: karate chop to the throat, knee the groin … they do not work in real situations,” the co-founder of BeWater Martial Arts & Wellness in Hong Kong explains.

He says if you happen to be a 50kg (110 pounds) Asian woman, like this South China Morning Post reporter, and about to duke it out with an 82kg (180 pounds) opponent like Junior, your meagre kicks, or jabs with your skinny fists, will not be effective. “Even if you learn to punch properly you’re still limited in terms of strength,” he says. Besides, such moves will only enrage your assailant, and make the situation even worse.

What if you gouge the eyes? “It’s Hollywood. In real life it doesn’t work,” says the 39-year-old, who cautions against learning self-defence tactics from the highly choreographed fight sequences in Bruce Lee and Jackie Chan films. As many have learned the hard way, real fights are nothing like the movies. Junior says we have an inbuilt instinct to protect our vulnerable areas like the eyes.

Three useful Brazilian jiu-jitsu self-defence moves to thwart an attack

As for groin shots, many predators expect this response nowadays, so they are highly focused on protecting the area, he adds. So what self-defence techniques can a person use if they are smaller and weaker than their assailant?

This is where martial arts basics come in handy. According to Junior, Brazilian jiu-jitsu, which evolved from strike-heavy Japanese jiu-jitsu, was conceived for individuals of smaller stature to overpower bigger opponents.

Brazilian jiu-jitsu is a ground-fighting art form – you subdue your opponent by getting hold of them and forcing them to the ground.

Junior won the ACBJJ (Absolute Championship Berkut Jiu-Jitsu) World Championship title in Moscow last year.

The sport reached Latin America via judo master Mitsuyo Maeda, a jiu-jitsu specialist. He settled in Brazil in the early 20th century with the help of diplomat Gastão Gracie. As a gesture of appreciation, Maeda taught jiu-jitsu to Gracie’s children, Carlos and his younger, less physically athletic sibling, Hélio.

It soon evolved into a fighting technique that was perfect for a body type like Hélio’s. Based on the principles of leverage, weight distribution and positional advantage, it could be used to subdue a bigger, fitter opponent. This discipline became internationally widespread as Brazilian jiu-jitsu.

Taking the fight to the ground offsets the differences in strength, weight and size between you and the attacker. On the floor, players’ strength is less useful but technique becomes crucial. “This allows a weaker person to have an advantage over a stronger, bigger opponent,” explains Junior.

In the introductory classes available at Junior’s studio in Hong Kong’s Central business district, students go through common scenarios that require self-defence in a close-combat situation. The situations are based on US police reports, research on predators’ behaviours, and the accounts of female attack victims.

“Brazilian jiu-jitsu empowers women because they start realising these techniques are not based on physical strength or size, but on correct application of techniques to certain situations or scenarios,” Junior says. These methods are not just for women but for anyone to defend themselves in a dangerous situation, he says.

Importantly, the techniques are aimed at gently subduing the foe, rather than inflicting so much damage it could result in legal ramifications later.

“[For example] I can apply a choke hold and tell him to calm down otherwise I will put him to sleep,” he says. “It’s based on the principle that I want to be safe but the other person needs to be safe as well.”

Here are five life-saving moves Junior recommends you should use.

The wrist grab escape

If the attacker tries to take you by force by the wrist to drag you into an alley or vehicle, this technique is based on the principles of leverage and positional advantage against your attacker, to create as much resistance as possible. Create a strong heavy base; exert a strong stance to break their grip on you.

Bear-hug-from-behind escape

If the assailant tries to drag you from behind, set yourself in a strong set position. Lock the attacker’s leg, offset their balance and attack their knee. When they are on the ground, sit on the attacker’s knee, and hold the heel and ankle.

Raise your voice

Yell. Scream. Create a scene. Predators do not want to get caught. Mostly, they do not want to be in a struggle, so seek victims they believe are easy to subjugate. “Don’t feel shy when your life is in danger; use your voice,” says Junior. This also signals to the assailant he is in for a struggle.

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Be prepared

In a dangerous situation, we all have a fight-or-flight response. But for some women, the overwhelming shock and fear might make them freeze, which makes them more vulnerable in the attack.

That is where practice comes in, as more familiarity with a close combat scenario can help alleviate fears. According to Junior, people need to get comfortable in close-range engagement.

“A lot of people can’t even deal with close contact,” he said, adding that you need to get accustomed to using grabs and other physical tactics with a heavier opponent. That doesn’t mean you need to advance to black-belt level of martial arts; all you need is some familiarity and confidence to prepare for a real-life confrontation.

Joint attacks

In this discipline there are countless strategies to foil the attack. “Most of the techniques are not strikes but are attacks on the joints … we teach techniques to attack every joint in the body, like shoulder locks, arm locks, wrist locks, knee bars, ankle locks, heel hooks,” he explains. Sometimes this means applying pressure to a precise joint such as squeezing the arm in way that you can break or dislocate it.

This is all part of Junior’s quest to bring life-saving skills to many. He hopes women can empower themselves to protect their body thanks to this knowledge. “It’s to say: ‘No, my body is my temple and only I allow who gets close to me.’ That is why I feel it’s so important people learn this like they would a first-aid course.”

For years he has been teaching self-defence workshops to the masses. He will again be at the fitness and wellness festival, Iris: Your Escape, in April.

He will also be doing self-defence classes specially designed for women’s groups such as RainLily, a sexual violence crisis centre, while this month, BeWater is hosting a self-defence class on Women’s International Day on March 8.