How dangerous is it to choke someone unconscious or to be choked unconscious?

Question

A little background:

I was practicing with my instructor one morning. It was just him and me and we were doing free training of submission grappling. At one point I managed to get him in a choke hold and I expected him either to break free or to tap out. When I looked down at him his eyes were rolled back and only partially opened. I released him and he lay there gasping for a moment. I asked him if he was alright and he kind of blinked a few times and said "Of course I'm alright, why do you ask?" I replied "Because you appeared to be dying." None of his students had ever beaten him before in submission grappling. He told me later that he thought to himself "this is a tight choke, I should consider tapping out" and then he saw himself running through a meadow, without a care in the world.

It kind of freaked me out a little, because we were the only two people there, and I wasn't sure what I would have needed to do if he hadn't immediately woken up (other than call 911). I know some schools make a point of choking their students unconscious at least once, so they know what it feels like. Personally that has always struck me as unnecessary.

What kind of dangers are there in choking someone (or being choked) to the point of unconsciousness?

Answer 1

Being choked unconscious might not be good. But we have very little evidence that shows that it's bad to any significant degree, and considerable evidence that being choked all the way out doesn't seem to be of notable danger. Let's look at a few different kinds of evidence.

A side note: we must keep in mind the vast difference between being "choked out" to the point of tapping and being choked unconscious. We will not use the former interpretation. For us, "choked out" means choked past the point of losing consciousness.

Another side note: in medicine, choking and strangling are specific technical terms. We won't be using those more precise definitions.

Studies Where We Choked People Unconscious In a Lab

One obvious thing to do is choke someone unconscious while they're connected to a bunch of sensors, and see what happens.

There has been limited medical research regarding neck restraints. One of the first studies was conducted by the United States Military in 1943. A team of American military scientists examined the effect of acute cerebral anoxia —a short and severe lack of oxygen to the brain. To do this, they used an inflatable cervical pressure cuff designed to induce temporary arrest of circulation without affecting the respiratory tract; essentially, a mechanically created carotid pressure hold. The cuff was held down to the lower third of the neck and pressure increased to 600 mm of mercury within one-eighth second. One hundred and twenty six prison volunteers and 11 diagnosed schizophrenic patients were fitted with the cuff which was tightened until unconsciousness was induced. The average time from arrest of cerebral circulation to loss of consciousness was six to eight seconds. The study concluded that arrest of cerebral circulation in normal young men results in fixation of the eyes, tingling, constriction of the visual fields, loss of consciousness, and brief, mild tonic and clonic seizure after restoration of the blood flow. This study, though dated, is perhaps the largest study ever conducted in terms of the sheer number of participants. No deleterious effects were observed from repeated tests on these subjects.

(Source: PDF)

Now, I'm not sure I trust these researchers. They're in the military, conducting tests on prisoners and mental patients. Perhaps their evaluation of deleterious effects is not, shall we say, the most thorough. So we have Ken Endow's DANGER IN THE JUDO CHOKE?, where they arrange an array of sensors to some guys and choke them out:

Is there any danger in the use of shimewaza? This is what a team of experts came together to try to discover. Representing several of Japan's foremost medical schools and universities as well as the Kodokan, this group of medical specialists and ranking educators used the electroencephalograph to detect brain changes; the earoxymeter for blood oxygen saturation, the sphygmomanometer for arterial blood pressure; the plethysmograph peripheral blood vessel reaction and the micropipometer for skin temperature changes. Other studies probed the plasma protein concentration, blood water volume, hematrocrit complete blood count, eosinophil count and urine 17 keto-steroid content.

...

After only 10 seconds of choking, the victims fell unconscious. As soon as they were diagnosed unconscious, the performer released them and, the subjects remained unconscious from 10 to 12 seconds. During this period the victims some times developed clonic, a jerking or fluttering, cramps. All subjects woke up spontaneously.

...

As the subject regained consciousness spontaneously his electroencephalogram readings returned to normal. It should be repeated that in all the cases the performer released his grip immediately after the subjects fell unconscious, thereby limiting the effect of choking to a short period. But had the strangulation continued serious aftereffects would have been expected.

...

The electroencephalograph recorded symptoms very similar to that of a short epileptic seizure.

Those findings sound alarming but not actually dangerous or troubling.

We also have this three-way comparison between judoka (who choke and get choked regularly, though not normally to unconsciousness), boxers (who punch and get punched in the head regularly), and a non-choking, non-punching control group. It's pretty straightforward 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 engaged in violent sports which can cause brain impairment. In fact, while professional boxers may show brain functional impairment in comparison to normal subjects, judoka do not.

So we see that normal judo practice, which might involve the occasional choke-out, has no evidence of being injurious to brain function in the long term. This is supported by another study where they choked some guys unconscious and looked at their brain waves. Again, the results are not a cause for worry:

Spectral analysis of electroencephalography changes after choking 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 of global field power in the delta- and theta-range occurred, while physiological alpha-power decreased. These changes in the low-frequency range reached a statistically significant level within a time span up to 20 s after choking, which was performed at an average choking time of 8 s. In no case did choking provoke neuropsychological symptoms. Yet, spectral EEG-analysis revealed subclinical changes of brain function.

CONCLUSIONS: Choking in judo may induce subclinical electroencephalographic perturbations. The extent and duration can be objectified by means of spectral analysis of EEG data, global field power computation, and brain-mapping representation.

Let me reiterate the non-troublesome 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.

Weighing this kind of evidence, the Kodokan issued two warnings, the first of which has good evidence, the second of which seems a reasonable precaution:

To prevent any dangers that may accompany the choke, the Kodokan bulletin advises it is dangerous to perform the choking [both] on subjects with cardiac disorders or those suffering from hypertension since the load to the heart and the rise in blood pressure is marked. It is also advised that it is dangerous for youngsters whose nervous system and heart have not yet attained complete development.

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

Epidemiological-Type Evidence Where We Check How People Turned Out After They Get Choked Out In Training and Competition

If being choked out was known to produce injuries or deaths in training or competition, that sure would be a sign that we shouldn't do it. Yet, judo organizations keep good records, and we find the opposite. A judoka-doctor argues persuasively from empirical evidence that choking someone unconscious in the manner of judo, Brazilian jiu-jitsu or modern no-gi grappling is reasonably safe:

[Choking in judo] is considerably less dangerous than a "knock-out" in boxing and there is no necessity of completely excluding "choking" from Judo, provided necessary precautions are taken.

There are, however, three main dangers of choking based upon the above experiments.

• To perform a "choking" hold on subjects with cardiac disorders or hypertension.
• To apply "choking" on youngsters whose central nervous system and heart have not yet attained complete development.
• To continue to hold after the subject falls unconscious.

Since the advent of Judo, first developed by Professor Jigoro Kano in 1882, no death directly attributed to choking has been reported. There are four main reasons why fatalities do not occur:

• Choking, whether in practice or competition is supervised and observed by qualified trained instructors and officials.
• The contestant submits before unconsciousness occurs.
• After choking the contestant regains consciousness naturally and spontaneously without difficulty in ten to twenty seconds.
• The immediate application of artificial respiration by the qualified instructor or official prevents prolonged hypoxia.

Choking in Judo is safe because since the advent of Judo statistics show no fatality attributed to the shime-waza. Moreover, scientific studies on choking reveal no deleterious after effects. Finally, the precautionary rules and methods used make the technique of choking a relatively safe means of subduing an opponent in competition.

(Source: E. K. Koiwai, M.D., How Safe is Choking in Judo?)

Our dear doctor goes further, investigating a number of deaths due to law enforcement choking various persons, and finds:

In all 14 cases, this author has noted evidence of injuries to the structures of the neck from bruises, ecchymosis, hemorrhages to fractures of the cartilage of the neck (Cases 1, 5, 10, 13, and 14), and intervertebral discs (Case 7).

He makes the point that these injuries suggest improper application of the choke, such that these should not be considered in the same category as actual judo techniques:

If the carotid artery hold is properly applied, unconsciousness occurs in approximately 10 seconds (8-14 seconds). After release, the subject regains consciousness spontaneously in 10-20 seconds. Neck pressure of 250 mm of Hg or 5 kg of rope tension is required to occlude carotid arteries. The amount of pressure to collapse the airway is six times greater.

(Source: E. K. Koiwai, M.D., Deaths Allegedly Caused by the Use of "Choke Holds" (Shime-Waza))

A Dissenting Case Report

Owens and Ghiadiali present a contradicting possibility. From the abstract:

A case is presented of a patient with signs of anoxic brain damage, with psychometric investigation showing memory disturbance consistent with a left temporal lobe lesion. This patient had been frequently strangled during his career as a judo player; it is suggested that such frequent strangulation was the cause of the damage. Such an observation indicates the need for caution in the use of such techniques.

I do not have access to the full text. It is not clear that judo is well implicated in this case, nor do we know the extent to which this individual was choked out (how often, how long, et cetera), nor can we extrapolate from this one data point. Even being charitable, the conclusion to take from this case would be "don't be choked all the way to unconsciousness, and if you do, don't do it frequently". NB: this is not shown, merely suggested as a cause for further research.

My Tentative Conclusion

There are some contraindications for being choked: heart conditions, hypertension, young kids. But people who are choked out for ten or thirty seconds seem to be fine within five minutes, and certainly by the next day. Being choked out repeatedly would seem to be a bad idea.

I'm not going to go out and try to get choked out. But if it happens in the course of training or competing, the only thing I'm worried about is that someone notices before too much time passes. Students should know to pay attention to their partner and not hold onto a choke with a limp partner. Instructors should pay attention to students who are grappling, taking particular note of those caught in a choke, and make sure nobody holds on to a choke after the other person passes out. These simple precautions have, according to the data, largely prevented choke-related serious injury in one of the world's most practiced martial arts.

Normal practice of grappling chokes is almost entirely safe. One instance of being choked out and immediately resuscitated doesn't appear to have any serious negative consequences, say both anecdotes and the data.

So barring contraindications, choke away, judoka.

Answer 2

There are two types of choke:

• Blood Choke: Cerebral blood flow (CBF) chokes involve restricting the flow of blood to the brain, thereby denying it of oxygen.
• Strangle: Windpipe (Air) chokes involve compressing the trachea which deny the entire body of air.

This shouldn't be done in training to the point of unconsciousness as it can cause tissue damage and long term health issues.

Properly 'tapping out' is vital when practicing a choke.

Brain tissue can be damaged or die completely if CBF is partially or completely occluded causing ischemia. Although the person should pass out before damage occurs there could be underlying health concerns that may cause issues.

When practicing BJJ, I always tap out before passing out: I just ensure there is the necessary tightness. Personally, even under training conditions with supervision and the person releasing right away, I still would not want it to get to the point of passing out.

Answer 3

and I expected him either to break free or to tap out. When I looked down at him...

There would have been a physical sign that your instructor had lost consciousness, like his muscles relaxing and possibly a slight change in posture. You need to be considerably more aware than you were. You cannot always rely on your training partner to know when to tap out, as they may try to tough it out and/or not know their own limitations.

You should only be taking your choke holds to this level when you have reached a level of proficiency, and part of that should be knowing how to handle the situation if unfortunate accidents happen.

I know some schools make a point of choking their students unconscious at least once, so they know what it feels like. Personally that has always struck me as unnecessary.

People will have different views on this, but personally I think it is important to know your technique inside out and back to front. Being choked out benefits both participants:

• the recipient gets to experience the sensation of losing consciousness via the choke, this helps them know their limits, know the power of the technique, and know when they should be submitting
• the person giving the choke gets to know the stages the recipient will go through as the choke progresses. If you expect to use a potentially dangerous technique like this on a regular occasion (either in training or in the ring) then it is vital you don't over do it and know when to stop despite what your opponent may be indicating to you.

Answer 4

Worth making the distinction between a blood choke and a air choke. ie, are you cutting off the air ( through the throat) or the blood (through the arteries).

Throat choking is a lot more dangerous because of the damage you can do to the actual throat. Can cause swelling, etc and can cause people to die some time later.

Blood chokes, less dangerous, but can still cause problems for people who are predisposed to various conditions.

Similar kinds of risk as being hit in the head. Things can go wrong. Its worth knowing the first aide responses to the likely scenarios you might find yourself in.

Answer 5

There are two types of chokes: a blood choke, in which blood flow to the brain is, at least temporarily, halted; and an air choke, in which compression to the trachea or chest stop airflow into the body, and thus oxygenation of the blood.

Both are inherently dangerous. During an air choke, excessive pressure can lead to the collapsing of the trachea or lungs, making it impossible for the victim to draw breath. Treatment for this is dependent upon the cause: a tracheotomy (in the case of a collapsed trachea) or chest tube (in the case of pneumothorax) may be required to reestablish breathing.

Blood chokes, on the other hand, can in rare cases lead to the collapsing of arteries. One theory is that compression of the carotid artery, in addition to causing cerebral anoxia, also sends a signal via the vagus nerve to the heart, which can cause arrhythmia or reduce bloodflow further to as low as 1/3 normal volume.

However, it should be noted that the greatest threat, cerebral anoxia, causes brain cell death after 4 to 6 sustained minutes. All other dangers are minute in comparison, and odds are against long term damage or death. That said, it's worth remembering that even a simple hematoma (bruise) can cause death (a clot can break away and cause a stroke or heart attack or other infarction), and training in any sort of martial art should be treated with the respect it deserves.

Edit

It should be noted that the dangers inherent in martial arts chokes are also similar to those of breath-play in the S&M community. In an article by Jay Wiseman, who is, in his own words:

I was an ambulance crewman for over eight years. I attended medical school for three years, and passed my four-year boards, (then ran out of money). I am a former member of the American Academy of Family Physicians and a former American Heart Association instructor in Advanced Cardiac Life Support. I have an extensive martial arts background that includes a first-degree black belt in Tae Kwon Do. My martial arts training included several months of judo that involved both my choking and being choked.

A simple rundown is this:

The primary danger of suffocation play is that it is not a condition that gets worse over time (regarding the heart, anyway, it does get worse over time regarding the brain). Rather, what happens is that the more the play is prolonged, the greater the odds that a cardiac arrest will occur. Sometimes even one minute of suffocation can cause this; sometimes even less.

So why can this happen? When denied oxygen, the heart contracts at multiple sites, usually in the ventricular region (causing "premature ventricular contractions" or PVCs). In the event that a PVC occurs during a phase in which ventricular depolarization is occurring (called PVC-on-T or R-on-T), then ventricular fibrillation (a form of cardiac arrest) can occur. The more PVCs occur, the higher a likelihood of an R-on-T event, and thus the higher a likelihood that event will trigger cardiac arrest.

Secondarily (and briefly, since detail is gone into in the article), the build up of CO₂ in the blood stream will cause a dissociation in existing H₂CO₃ (carbonic acid, an equilibrium of H₂O and CO₂) into HCO_3^- (bicarbonate) and H⁺ (an acidic Hydrogen ion). This build-up of acid can shift the pH lower. Since both the increase of blood carbon-dioxide and decrease of blood oxygen lower the pH, the effects of suffocation can cause the pH to plummet. pH levels below 6.9 or above 7.8 are considered incompatible with human life.

Answer 6

As a former LAPD police man who went through academy training in the early 70s, I can give testimony about the bar arm control hold and its effects, on other police cadets and myself as well. We were taught to know what to do when gaining consciousness, how to identify by hearing, where our main threat was (man with a gun) and how to proceed. Naturally in order to do that, we were choked out no less than 20 times during training. We were trained to use the bar arm control hold, which consisted in turning the adversary around from a frontal position, by keeping our gun leg back, extending our left hand inches beyond his right arm and hitting and pushing his right shoulder hard. Well applied, this maneuver resulted in turning the person around, into the cutting side of our right forearm, while our left hand was locked on to our right one, applying force to the subject's neck pressing him aginst our chest. Ounce that maneuver was done, his arched body was taken down hard to the ground by retrieving our left leg.If the choke hold was well applied, he was supposed to be out by the time he hit the floor. When the choke hold was applied to me by training officers, supposedly experts in martial art, it was not painful at all. It was swift and quick, because the martial arts expert, maintained at all times the pressure on the neck and of course there was no resistance from the me, since this was just a demonstration. The problem started when the choke hold was applied by trainee to trainee in an effort to get it right. In my class, at least two persons were taken out of the field by ambulance, and one was never seen again. In my case, weeks after wrestling classmates ussually 40 to 60 pounds heavier than me, and being choked out almost daily, or even choking out some classmate, I started to have migraines, vertigo, pain and stiffness of neck and other symptoms. I reported all these to my superiors at the academy, but complaining about pain was not part of the job description, so I went on to graduate and stayed on the job for about 7 years. Eventually I was given a stress IOD type pension. An evaluation by a Neurologist was performed a couple of years ago, and subsequent testing (brain and cervical MRIs and xrays) revealed significant and important lesions from c3 to c7. These lesions are congruent with a great amount of pressure applied to my neck. They are degenarative, and may be the cause of headaches, sleep paralysis, and a whole series of symptoms, that are often confused with stress and other psychological ailments.

To conclude this commentary, let me just emphasize that choke holds applied by martial arts experts may result and minimal to no permanent lesions, but the barm arm control hold, or the caratoid version, use in law enforcement by officers, even when it is well intended to just control and avoid lethal force, is not being applied by experts, nor to persons that may tap out, which may lead to: death...permanent neurological injury to brain and back to the suspect, it may also be the cause of lesions to back and knees of the officer, because if it happens in the field, the patient is taken down hard to the ground and the officer absorbs the impact falling hard on his knees, not on a training padded surface or grass, but ussually on a concrete paved street. I respectully advised retired or active officers to consider my experience and seek profesional neurological evaluation when faced with headaches, tingling sensation of back of head, hands and feet, pain on back of legs, unsteady gait, urinary incontinence of any type, pain in lower back that extends to gluteus, even lose of sexual drive. In my humble opinion any officer who went through the barm arm experience and lost of consciousness at the academy, should have a neurological evaluation and testing.

The same advice goes to any person, whom might have been choked out, lost consciousness and is know exprience some of this symptoms.

Thanks for your patience and tolerance

E.R. Jimenez

Answer 7

The only answer that can be given is that it is very dangerous. The reason for this is that everyone has different biological and physical toughness and you, as their opponent, cannot make any valid guess as to how much they can take. (And the truth is that they wouldn't know either if they were honest.)

Back when I was young and stupid, I used to tough out chokes on a regular basis. I look back and cringe at that behaviour. Thankfully, I always erred on the side of caution when attempting such a move on my opponent and would discontinue my attack if I thought they were trying to tough it out themselves. I have been penalised for this in contests, but I'll take the points against me rather than the possibility of a life of regret that I didn't stop sooner.

There's a reason what we do is called "martial" arts. We learn very efficient ways to kill people. With great power comes great responsibility. That's not just a movie quote, it's an honest to goodness fact. Always err on the side of not hurting your opponent.

Answer 8

The distinction between "blood choke" and "air choke" does not make sense from a medical point of view, especially when unconsciousness is involved.

Any form of unconsciousness is perilous (in a sense of "possibly lethal"). You are entirely right about feeling scared, unconsciousness is scary. The body loses its adverse-effects reflexes, which can easily result in death by aspiration/asphyxia even on an entirely healthy person. Also, secondary effects (e.g. circulatory or neurological ones) which you may or may not notice and which you may or may not be able to handle can join in at any time.
Certainly, not everybody who goes unconscious for a moment dies, but it's something you cannot safely assert at that moment.

Hyperextension of the neck as learned as one of the basic measures in every first aid course is helpful in such a situation, it literally saves lives. It's the first thing you want to do when someone doesn't come back within a few seconds.
Since you said you wouldn't have known what to do, this is a valuable thing to look into.

As for which is more dangerous, "blood" or "air" choke, both are -- also in absence of unconsciousness -- equally dangerous insofar as both can easily cause severe side effects and death.

It doesn't take much to break the thyroid cartilage, and if that happens, you're in trouble (or rather, for the time being the other person is, you'll be in trouble when the police arrives).

It also doesn't take much on some people to stimulate the vagus nerve so they develop a sudden bradycardia with extreme hypotension. This is very individual, and you only know when it's too late. Extreme hypotension can, even when people tell you "of course I'm alright" a few minutes later, result in organ failure (usually the kidney) up to 48 hours later.
Also, a "blood choke" results not only in oxygen depletion, but also in a sudden change of blood pressure in the brain. Most martial artists should hopefully be healthy people, but you never know -- there are young and apparently healthy people with aneurysms, too. When you find out, it's too late.

Thus, all in all, choke with care, be responsible and stop early before someone goes unconscious.

Answer 9

I recently found an article by Wendy Gunther Sensei, which asserts that during a controlled study there was no long term damage from chokes. Short term interruptions in blood flow, transient EEG anomalies but in each case the recipient of the choke returned to full functionality quickly. The referenced article does mention some more serious consequences that could occur, but should not if training under a competent instructor in a controlled environment. This contradicts what I've been told by others, and I think the subject merits further research.

Update: @Dave Liepman asked me to check with the MD's in my dojo who assert that there are dangers to chokes. I'm still checking the facts, but Sempai said that one of our students who was a neurosurgeon found "pukka's" (phonetic spelling) on the brain of people who had suffered chokeholds, and that furthermore one of our top judo players (a national competitor who has more chokeouts than the rest of us put together) had an unusually large number of pukka's on his brain. I need to check how strong the correllation is - I know who the MD in question is, but he no longer practices with us. I'll see if I can get contact information and follow through.

Answer 10

I think chokes are some of the safest submissions in BJJ/Submission grappling and thus it's okay to train them as often as you want. I think the main factor in terms of danger is making sure you're training with someone you trust. Anything in martial arts can potentially be dangerous if your training partner has the wrong mindset.

Answer 11

On a healthy adult with no pre-existing conditions that could be exacerbated by the choke, it's not dangerous at all. The problem with that is you might only find out there was a condition after the fact.

Choking out your instructor - no big deal, he probably didn't get to where he is with a heart condition, and with his experience the onus to tap is really on him.

Choking out a white belt should be avoided at all costs. If there's a referee who's keeping an eye on things you can off course wait for the ref to stop it or for the tap (when I'm reffing I ask the athletes to keep their eyes open, the moment I see them lose focus, or if their eyes are obscured while in a choke I stop the match). If there's no ref present, you have to moderate yourself. If the tap doesn't come within a few seconds of sinking in the choke, let go. Either the other guy is stubborn and doesn't want to tap (don't let that become your problem by choking him out and finding he's one of the few cases where something bad happens!), or your choke wasn't very good. Either way, let go, move on to something else.