How do I knock someone out

How dangerous is it to knock someone out or knock them out?

Studies in which we suffocated unconscious people in a laboratory

Being unconscious might not be a good thing. (And we have to consider the huge difference between "choking" to the knocking and choking unconscious.) However, we have very little evidence that it is significantly bad, and substantial evidence that everyone is choked. The way out does not seem to be any notable danger to be:

There is limited medical research on neck braces. One of the first studies was carried out by the US military in 1943. A team of American military scientists studied the effects of acute cerebral anoxia - a brief and severe lack of oxygen in the brain. To do this, they used an inflatable cervical pressure cuff to induce temporary cardiac arrest without affecting the airways. hold essentially a mechanically generated carotid pressure. The cuff was pressed to the lower third of the neck and the pressure rose to 600 mm of mercury in an eighth of a second. One hundred and twenty-six volunteers in the prison and eleven diagnosed schizophrenic patients were fitted with the cuff, which was tightened until unconscious. The average time from cessation of cerebral circulation to unconsciousness was six to eight seconds. The study concluded that cessation of brain circulation in normal young men results in eye fixation, tingling, narrowing of visual fields, unconsciousness, and a brief, mild tonic and clonic seizure after blood flow is restored. While this study is dated, it is perhaps the largest study ever conducted in terms of sheer number of participants. When tested repeatedly on these subjects, no adverse effects were observed.

(Source: PDF)

I am not sure if I trust these researchers. (They are in the military doing tests on prisoners and the insane. Perhaps their adverse effects assessment is not the most thorough.) So we have Ken Endow's DANGER IN JUDO CHOKE? where they put a bunch of sensors on some people and choke them:

Is there any danger with using Shimewaza? This is what a team of experts came together to find out. Representing several of Japan's leading medical schools and universities, as well as the Kodokan, this group of medical specialists and senior educators used the electroencephalograph to detect changes in the brain. the eroxymeter for blood oxygen saturation, the blood pressure monitor for arterial blood pressure; the peripheral blood vessel response of the plethysmograph and the micropipometer for skin temperature changes. Other studies looked at plasma protein concentration, blood water volume, whole blood count for hematocrit, eosinophil count, and urinary keto steroid levels 17.


After only 10 seconds of suffocation, the victims passed out. Once they were diagnosed with unconsciousness, they were released by the subjects and the subjects remained unconscious for 10 to 12 seconds. During this time, victims sometimes developed clonic, jerky, or fluttering convulsions. All subjects woke up spontaneously.


When the subject spontaneously regained consciousness, his electroencephalogram readings returned to normal. It should be repeated that in all cases the performer immediately released his grip after the subjects passed out, thereby limiting the effects of suffocation to a short period of time. However, if strangulation had continued, serious aftereffects would have been expected.


The electroencephalograph recorded symptoms similar to those of a brief one epileptic seizure were very similar.

These results sound alarming, but not really dangerous or worrying.

We also have this three-way comparison between judoka (who regularly chokes and chokes, albeit normally Not unconscious), boxers (who regularly punch and get hit in the head), and a control group who don't choke and don't hit. It's pretty simple what they found:

Long-term effects of boxing and judo choking techniques on brain function.

Author: Rodriguez G, Vitali P, Nobili F.

Source: Italian Journal of Neurological Science, 19 (6): 367-72 1998

This study shows the relevance of the neurophysiological assessment of athletes who engage in violent sports that can lead to brain impairment. While professional boxers may have impaired brain function compared to normal subjects, this is not the case with judoka.

So we see that normal judo practice, which can occasionally lead to choking, has no evidence of long-term impairment of brain function. This is backed up by another study where they choked some guys unconscious and looked at their brain waves. Again, the results are nothing to worry about:

Spectral analysis of electroencephalographic changes after suffocation in Judo (Juji-Jime).

Author: Rau R, Raschka C, Brunner K, Banzer W.

Source: Med Science Sports Exercise, 30 (9): 1356-62 1998

Results: A significant increase in global field power in the delta and theta range occurred while the physiological alpha power decreased. These changes in the low frequency range reached a statistically significant level within a period of up to 20 seconds after asphyxiation, which was performed with an average asphyxiation time of 8 seconds. In no case did suffocation cause neuropsychological symptoms . However, the spectral EEG analysis revealed subclinical Changes in brain function.

CONCLUSIONS: Choking in Judo can lead to subclinical electroencephalographic disorders. The extent and duration can be objectified by means of spectral analysis of EEG data, global field power calculation and representation of the brain image.

Let me repeat the non-intrusive aspects of their results: these changes in brain function were neither brain damage nor injury, and the results were less than what a doctor would consider problematic.

The Kodokan weighed this type of evidence and issued two warnings, the first containing good evidence and the second being a reasonable precaution:

To avoid dangers that with suffocation may be associated, it is pointed out in the Kodokan bulletin that it is dangerous to suffocate [in both] in patients with Heart disease or on people with high blood pressure, since the load on the heart and the rise in blood pressure are noticeable. It should also be noted that it is dangerous for adolescents whose nervous systems and hearts have not yet reached full development .

(Source: Ken Endow, DANGER IN JUDO CHOKE?) You can see details here in a terrible pseudo-PDF format.

Epidemiological evidence where we review how people have evolved after being suffocated in training and competition

If it were known that asphyxiation in training or competition would lead to injury or death, it would surely be a sign that we shouldn't do it. Judo organizations keep good records, however, and we find the opposite. One judoka doctor convincingly argues from empirical evidence that it is fairly safe to choke someone who is passed out like judo, Brazilian jiu-jitsu, or modern no-gi grappling:

[Choking in Judo] is significantly less dangerous than "knocking out" in boxing, and there is no need to completely exclude "choking" from judo provided the necessary precautions are taken.

However, based on the experiments above, there are three main choking hazards.

  • To "choke" on people with heart disease or high blood pressure.
  • Use of "choking" in adolescents whose central nervous system and heart have not yet fully developed.
  • Continue to hold after the subject has passed out.

Since the advent of judo, first developed by Professor Jigoro Kano in 1882, no deaths directly attributable to asphyxiation have been reported. There are four main reasons why there are no deaths:

  • Asphyxiation, whether in practice or in competition, is monitored and observed by qualified trained instructors and officials.
  • The candidate submits before passing out.
  • After suffocating, the participant will regain consciousness naturally and spontaneously in ten to twenty seconds with no difficulty.
  • The immediate use of artificial respiration by the qualified instructor or official prevents persistent hypoxia.

Suffocating in judo is safe as no death has been attributed to shime waza since the emergence of judo statistics. In addition, scientific studies on asphyxiation show no harmful after-effects. Finally, the precautionary rules and methods employed make the technique of suffocation a relatively safe means of subduing an opponent in competition.

(Source: EK Koiwai, MD, How Safe is Choking in Judo?)

Our dear doctor goes further and is investigating a number of deaths from asphyxiation of various people by law enforcement agencies. In doing so, he notes:

In all 14 cases, this author found evidence of injuries to the neck structures from bruising, ecchymosis, bleeding to fractures of the cartilage of the neck (cases 1, 5, 10, 13 and 14) and intervertebral discs (intervertebral discs). Case 7).

He points out that these injuries indicate improper use of the choke, so these should not fall into the same category as actual judo techniques:

When the carotid artery hold is properly applied, loss of consciousness occurs in approximately 10 seconds (8-14 seconds). Once released, the subject will spontaneously regain consciousness within 10 to 20 seconds. A neck pressure of 250 mm Hg or 5 kg of rope tension is required to close the carotid arteries. The pressure to collapse the airways is six times greater.

(Source: EK Koiwai, MD, Deaths Allegedly Caused by Use of Choke Holds (Shime-Waza))

A different case report

Owens and Ghiadiali offer a contradicting possibility. From the summary:

A case of a patient with evidence of anoxic brain damage is presented, with a psychometric examination showing a memory disorder consistent with a left temporal lobe lesion. This patient had been strangled many times during his career as a judo player; It is believed that such frequent strangulation was the cause of the damage. Such an observation indicates that caution should be exercised when using such techniques.

I don't have access to the full text. It is not clear that judo plays a good role in this case, nor do we know the extent to which this person has been suffocated (how often, for how long etc. ), we can still extrapolate from this one data point. Even if you're a nonprofit, the bottom line from this case is, "Don't be suffocate to the point of unconsciousness , and if you do, don't do it often. "NB: This won't shown but merely suggested as a reason for further research.

My preliminary conclusion

There are some contraindications to choking hazard: heart disease, high blood pressure, young children. But people who choked for ten or thirty seconds seem fine within five minutes, and certainly the next day. Getting suffocated over and over again seems like a bad idea.

I won't go out and try to get suffocated. But if it happens during training or competition, I just worry that someone will notice before too much time goes by. Students should know to take care of their partner and not to have to hold on to a thrush with a flaccid partner. Instructors should watch out for students dealing with the problem, especially those who are trapped in a choke, and make sure no one is holding onto a choke after the other person passes out. These simple precautionary measures are found to have largely prevented the severe suffocation injuries in one of the most widely practiced martial arts in the world, according to the data.

Normal clinging to chokes is almost entirely safe. A case of suffocation and immediate resuscitation doesn't seem to have any serious negative consequences, say both anecdotes and the data.

So, aside from contraindications, choke you, Judoka .


Subject: "The electroencephalograph recorded symptoms very similar to those of a brief epileptic seizure."… An event here and there will be probably Do not injure anyone, but repeated exposure can lead to worse conditions as well. Basic "rule of thumb": everything in moderation.

Dave Liepmann

@stslavik If the similarities between asphyxiation and epilepsy, as indicated by the electroencephalogram, may be true repeated Choking to the point of unconsciousness causing damage (such as shrinking of the hippocampus), resulting in a minor Increase in health risks. Since there are half a dozen choke-outs in a lifetime compared to uncontrolled epileptics, my bat signal does not go out.


The common groundhog is hiding every time his head, if it sees a shadow whether it is a predator or not. It develops this as an instinct for self-preservation; those who do not duck when the wrong shadow crosses are eaten. Just one thing to note.


"The LVNR system has specific guidelines for follow-up care. Officials must obtain on-site medical approval for anyone admitted to the LVNR, whether or not they have passed out. Anyone who has used the LVNR , an obligatory observation time of 2 hours applies. [...] not to be used on people with heart disease, children " - this clearly indicates that you are not at all worried about possible side effects or deaths :-)

Dave Liepmann

@Damon Kowai goes into detail on how law enforcement LVNR should not be considered equivalent to properly trained and applied martial arts thrushes. I would also be interested in whether the aftercare guidelines are medicine based or just a legal way to cover their backgrounds.