the science of a boxing knockout

The Science Of A Knockout In Boxing

There is nothing more exhilarating for a boxing audience than to see a fighter hit the mat in a knockout. But being on the losing end of a KO punch can damage a lot more than a pugilist’s pride—research suggests that the blows that cause knockouts can be debilitating to a boxer’s short and long-term health. Repeated blows to the brain can cause chronic damage such as personality changes and dementia. The fighter could even die if the punches have enough impact to cause uncontrollable brain swelling or bleeding.

Usually, the point of contact for a clean knockout is a fist to the chin or jaw. But the actual chin or jaw is not the ultimate reason the opponent goes to sleep.

When there is an impact to the head, the brain is rattled and smashes against the inner walls of the skull. This sometimes causes blurred vision, weakness in the legs, etc., which is technically a concussion. However, a person’s brain will shut down when rattled around too much, thus causing a knockout.

The chin and the jaw are the main targets because these two areas, when impacted, cause the most head movement, sending the brain into a rattling frenzy and most likely causing a quicker KO. The chin is the ultimate sweet spot as it causes the most sudden head-turning.

Hitting your opponent on the top of the head may cause damage, and the front of the face will cause swollen eyes and a bloody nose; however, these areas cause the least amount of head movement. The sides of the head cause a bit more “brain-rattling,” and the temples are softer, weaker spots as well.

Knockouts look like they are caused by one blow, which is sometimes the case early in the fight. However, most of the time, they are due to multiple hits – little-by-little brain-rattling and small concussions throughout each round.

Boxing always teaches you to keep your hands up and chin down. This is one of the best defences against a knockout. In turn, it is important to be braced for impact; if your neck and shoulders are too relaxed and you are struck by surprise, your head will snap much more severely than if you are braced for the impact.

Many fighters and coaches claim that working on their neck and shoulder muscles also helps; having a strong, stable neck can help combat the impact of a blow. However, doctors and scientists have stated that advantageous anatomy in avoiding knockouts is mostly genetic.

As hard as you physically can be enough to knock somebody out, especially if you aim for their temple. It is a very sensitive area of the head, and you don’t have to be insanely strong to cause considerable damage.


Chin – Striking someone on the chin can knock someone out because it forces the head to twist so suddenly and severely that it rattles the brain. 14. Temple – As a chin hit, a strong punch to a soft temple can cause extreme brain trauma that can easily knock someone unconscious.


Brain trauma is bad news and generally not the sort you wake up from later without major complications. So the answer is between 144lbs to 186lbs of force to knock someone out.


As for using a fist is very easy to knock people out if you are a heavy hitter. Every time I hit someone in the head, down they are usually knocked out. Like someone else mentioned, punch all the way through and hit the person on the jaw or in the eye. Train yourself by working out on a heavy bag and lifting weights.


There is no easier opponent to knock out than the aggressive opponent. All you need is the confidence to stand with him, a little bit of technique, and the timing to make your counters count. He goes forward. You keep your head down and put launch the biggest right cross you got into his face.


What Happens In The Brain When You Get Knocked Out In A Boxing Match?

In the blink of an eye, a well-landed punch can send you flying out cold before you even hit the floor. Of course, that’s something any professional boxer hopes for — or fears if he happens to be on the wrong end of a punch. But what happens within the brain when it suffers such trauma?

The brain is very fragile. It’s almost entirely made out of blood vessels and nerves. So we’re talking about a soft, mushy mass of tissue that controls all neural higher functions and commands you as a person. But despite this shortcoming, the brain is remarkably resilient at receiving trauma and ‘blackouts’ help in this respect, acting as a sort of defence mechanism.

All this mushy mass is floating in a clear, colourless liquid called the cerebrospinal fluid, which protects the brain from coming into contact with the skull. However, if the punch is good enough, it could cause the brain to slam into the skull from the acceleration caused by the blow and the deceleration caused by the muscles and tendons trying to prevent the head from spinning further.

When the brain slams into the skull, you get a trauma — brain cells start dying from the physical impact. This happens multiple times as the brain bounces off the walls of the skull on and off until the energy from the blow is dissipated.

The trauma causes an overwhelming number of neurotransmitters to fire simultaneously. This behaviour induces a form of nervous system overload, causing a system crash in the form of temporary paralysis.

Boxing Brains

Within the protective casing of your skull is a soft, mushy organ bathed in blood, laced with arteries, nerves, and veins. When you take a blow to the head so impactful it knocks you unconscious, a neurochemical reaction begins in the brain cells that cause cell death. According to a study published in the journal Neurology, the more cells die, the fewer brain tissue you have. It may explain why people who suffer from head injuries are never quite the same afterwards.

It all depends on how long they were knocked out, and more importantly, how severe the hit was. A professional boxer’s punch can generate 25 miles per hour and reach up to 32 mph — a force of approximately 400 kilograms. To put into perspective the immensity of a boxer’s power, the average person, without any boxing training, can generate only one-tenth of a professional’s force.

The impact of a KO-quality punch often leaves its victims with memory problems, mood changes, confusion, and a slower information processing speed. Brain volume is lost in the frontal and posterior brain regions’ white matter, which is the tissue that makes up the brain’s communication network essential for efficient processing. According to experts, even if it’s a seemingly minute five- to 10-percent loss, it will greatly affect the brain.  

The infamous knockout is the pinnacle thrill of the match, and without landing a gloved hand, the boxers’ performance results are lacklustre. The earliest quote from a first-century pugilist recorded into Greek literature said, “A boxer’s victory is gained in blood.” Mayweather and Pacquiao will be looking for blood and brain damage with millions and the glory of greatness at stake. 

The Scientific Formula For Knockout Power

the science of a boxing knockout3

When it comes to science, I believe the most important equation related to KO power is this:

Kinetic Energy (KE) = 1/2 mass x velocity^2

KE is the amount of energy in your fist, which you want to maximise at the point of contact. To maximise the KE:

  • Maximise the amount of weight behind the punch
  • More importantly, maximise the VELOCITY of your fist

I say that velocity is more important because, in the equation, it is squared. To all those lacking math skills or the Chinese math brain that I am so lucky to have been born with, you multiply it by itself when you square something.

So if velocity is 3, plug it into this equation, and you get 3^2 = 3×3 = 9.

If velocity is 4, you get 4^2 = 4×4 = 16.

Velocity is exponential, whereas mass is linear.

So back to the “snap back” myth – when you try to pull your fist back, you will lower the velocity you hit your opponent. It is simply not physiologically possible to instantly reverse the direction of your fist at the instant of impact. And as I said before, the bounce between head and fist renders this irrelevant anyway.

So now that we’ve busted one of the bigger myths about punching power and one of my past erroneous ways of thinking (sorry about that, but I’m always learning, too), let’s continue…

Because velocity is squared in the KE equation, it is more important to get knockouts and is the factor we can influence more.

How Can A Punch Knock You Out?

Several hypotheses have been put forth over time to explain how consciousness can be rapidly lost and spontaneously regained following mechanical head trauma. The knockout punch in boxing is a relatively homogenous form of traumatic brain injury and can thus be used to test the predictions of these hypotheses. 

While none of the hypotheses put forth can be considered fully verified, pore formation following stretching of the axonal cell membrane mechanoporation is a strong contender. We here argue that the theoretical foundation of mechanoporation can be strengthened by comparison with the experimental method of electroporation.

The Facts

The force of a professional boxer’s punch is approximately the same as that of a 9kg bowling ball travelling at 32km/h and colliding with a person’s head.

Not surprisingly, studies show that around 90 per cent of professional boxers will endure some form of brain injury throughout their career. At the same time, numerous researchers have found that between 15-40 per cent of boxers showed signs of chronic brain injury.

This culminated in approximately 488 boxing-related deaths from 1960 to 2011, with 66 per cent of these being attributed to head and neck trauma.

The Devastating Effects

Despite a major development in concussion protocols and management in recent years, died in combat sports is still a very shocking reality.

In 2014 alone, three professional boxers were killed by knockout punches they received during scheduled fights. Phindile Mwelase of South Africa, Oscar Gonzalez of Mexico and Japanese fighter Tesshin Okada all passed away, having never regained consciousness after being knocked out.

Biomechanics Of A Knockout Punch

So what makes a knockout punch? First and foremost, the technique is king. Combat sports coaches spend a lifetime perfecting the technical aspects behind the power in the punch production, so this will not be the focus of this discussion. However, understanding the biomechanics of the punch provides insight into why we need to train different movement patterns and how they need to be trained.

Power Production – From the Ground Up

Intuitively, anyone involved in striking arts understands that they will produce greater power if they “twist the hips” or “put their body behind the blow”. It just feels stronger. A seminal study by Filimonov & colleagues in 1985 examined the contribution of certain body parts to the punching power of boxing athletes of different levels. They found that the higher the level of athlete, the more they utilised their legs to generate power in the punch1. Similar findings have also been made with analysis of the shot put throw2, which is biomechanically similar to the punch.

Contraction Types

An assessment of muscular power should include tests that incorporate an eccentric component and tests that do not. These tests should be used to guide the type of exercises to be performed at different phases in a fighter’s programme. However, the function of the muscles in combat situations should also be considered.

The movement of the lower body is usually preceded by an eccentric contraction. For example, when throwing a punch, there is usually a set-up of the lower body to position the athlete to throw an attack. The hip, knee, and ankle flexed (eccentric loading) before extending (concentric movement) to produce force.

Symptoms of a Punch

the science of a boxing knockout2

A strike to the head that does not lead to unconsciousness may still induce a state characterised by reduced reaction speed and confusion. This is colloquially referred to as groggy since it resembles a person who has had too much grog, an alcoholic beverage. The gait may also be affected, and the afflicted person is then said to have developed spaghetti legs. This is dangerous for a boxer, as it reduces defending against other punches.

A harder strike can cause a loss of consciousness, typically with an almost instantaneous onset. By observing video sequences of knockouts, it can be concluded that the target of the punch is, in most cases, unconscious before a follow-up punch can land. This usually leads to a complete loss of muscle tone, and the boxer falls to the floor. 

Fortunately, consciousness is typically regained spontaneously within a few minutes or less. A loss of consciousness from which the person rapidly recovered was termed commotio cerebri (a shaken brain) by early researchers. They distinguished this from contusion cerebral (a bruised brain), where the function was lost and never regained (2, 3). This is also seen in boxing, where knockout boxers sometimes never regain consciousness and succumb to injuries.

But regardless of whether consciousness is regained or not, it is clear that brain regions responsible for maintaining consciousness must be impaired by the force of the incoming blow.

What Is The Difference Between Being Knocked Out And Suffering A Concussion?

They’re related, but not the same. For example, people used to think that you didn’t have to worry about being concussed if you didn’t lose consciousness. However, thanks to further research into concussions, we now know that, in about 90 per cent of diagnosed concussions, there is no loss of consciousness.

During any severe blow to the head, the same thing happens. The brain twists, the circuits break, and the damage sends the brain into crisis. But different parts of the brain can be affected. For example, concussions typically cause vision problems, disorientation, memory loss, headaches, balance issues, and a host of other ailments as the circuits that undergird these functions go down. But as long as the part of the brain responsible for consciousness is minimally affected, there’s no guarantee that you’ll be knocked out.

What Are The Long Term Effects Of Being Knocked Unconscious?

It depends on the severity of the injury. If you lose consciousness briefly and suffer a concussion, 75 to 90 per cent of people will fully recover in a few months. But severe damage to the brain can cause unconsciousness for days, weeks, or even longer. If there is internal bleeding or swelling in the brain, surgery may be necessary to relieve pressure on the brain. 

Severe injuries can also cause lasting effects that vary — including memory loss, paralysis, seizures, and lasting behavioural or cognitive changes — depending on the areas of the brain affected. But in those cases, unconsciousness is a symptom of the injury, not a cause of long term deficits.


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