The human body has evolved to shield its vital organs, from the brain's hard skull and meninges to the ribs and sternum protecting the heart and lungs. Even abdominal structures are safeguarded by muscular layers . In contact sports, understanding these vulnerabilities can give competitors the edge, allowing them to take down an opponent with a knockout or submission.
Author
- Adam Taylor
Professor of Anatomy, Lancaster University
Head and neck
In many sports, a blow to the head is a quick route to a knockout (KO). Strikes to the side of the head can lead to KOs - and sadly, sometimes death. These blows can rupture vital blood vessels around the brain, triggering rapid bleeding that causes instant symptoms or slowly compresses the brain, leading to a coma and eventual death.
Blows to the chin are usually much more effective for an instant KO. They can generate significant force by rotational acceleration through the brain tissue. They may also result in "diffuse axonal injury", where the force generated causes long nerves in the brain to stretch or tear.
The neck is often exploited in mixed martial arts (MMA) and jiu-jitsu. The rear-naked choke is one of the more effective, taking 8.9 seconds to render an opponent unconscious. This choke cuts off blood flow to the brain through the two main carotid arteries, which each deliver up to 590ml of blood to the brain per minute .
Unconsciousness from the heart stopping beating can occur in as little as eight seconds . Arteries running through the neck to the brain are also susceptible to direct trauma in combat sports, potentially leading to paralysis or even death.
Nerves and bones
The legs are a key target in combat sports, such as muay thai and MMA. Low kicks to the outside of the thigh and buttock area target the sciatic nerve - the largest nerve in the body. The sciatic nerve supplies muscles on the back of your leg and bottom of your foot.
Although this nerve is rarely permanently injured in most sports, repeated trauma can cause numbness, weakness or paralysis of the muscles it supplies.
Another target is a branch of the sciatic nerve called the common peroneal nerve . It sits underneath a bony bulge on the outside of your leg just below the knee. Repeated targeting of this nerve can result in the inability to stand because the foot drops and the person can't sense its position or inability to move the affected foot.
Because of the direction of kicks to this area, almost 60% of muay thai fighters report contracture (shortening) of their calf (gastrocnemius) muscle, in response to repeated trauma.
Armbars and ankle locks are also rapid ways to bring things to an end. Armbars involve trapping the arm in such a way that the elbow is in the hyper-extended position, trying to force it beyond straight. On the back of the joint is a large bony bulge called the olecranon, which prevents over-extension.
If an opponent doesn't "tap out", the joint cavity and tissues of the elbow sprain or tear or the radius or ulna break .
Ankle locks are often described as one of the most painful locks. This is because, when done properly, it hyper-extends the ankle joint and compresses the achilles tendon, which is the largest and thickest tendon in the body and has many sensory receptors for pressure .
This is further exacerbated because many of the nerves passing through the ankle have little or no protection from muscle or connective tissues and there are 11 ligaments that support the ankle , all now having excessive forces stretch through them.
Abdomen
Attacking the abdomen is common in combat sports as it's an easier target to hit than the head. There are two blows to this area that can end a fight. Blows to the liver and to the spleen.
The liver sits on the right, protected by the ribs. But hitting the body over or just below this area can send shock waves into the liver that result in instant crippling pain because of the large number of critical nerves that sit behind it. These nerves are responsible for important functions including monitoring organ status and blood vessel diameter .
Some of these punches can result in death from internal bleeding. The liver receives a huge volume of blood: 25% of the heart's output . Any significant injury can tear the liver, causing fatal blood loss.
The left side can have similar consequences, tucked behind the lower ribs at the back on this side is the spleen, a soft and blood-filled organ which is often silently or subtly torn by blunt-force trauma, such as car accidents, contact sports or broken ribs.
It often gives no or vague symptoms and can bleed slowly after the initial injury occurrence, resulting in collapse or death a few hours after the event.
The heart
Commotio cordis is a rare cause of sudden death, occurring most commonly in young male athletes who are struck in the chest. It occurs in the absence of visible heart damage.
This trauma causes a fatal interruption to the electrical activity of the regular heartbeat. The reason that all chest blows don't result in this outcome is because it is believed to have to happen at a specific part of the electrical conduction through the heart - called the T-wave, which usually accounts for about 1% of the heartbeat cycle time. The T-wave increases with exercise , which is why commotio cordis is usually seen in exercising young athletes.
For commotio cordis to occur, the impact must generate roughly 50 joules of energy, which is roughly equivalent to a baseball travelling at about 40mph .
The illegal stuff
Most of the above blows are allowed in most combat sports. However, some things that occur during fights aren't. Punching the back of the head - so-called rabbit punches are banned because they can snap the cervical vertebrae at the top of the neck and potentially the spinal cord, which can have significant lifelong injuries, or even death .
Likewise, groin strikes are banned too, they can prevent people from having children and are incredibly painful because of the vast number of highly sensitive nerves that supply that area in men and women.
While reading this may make you wince, it also brings a newfound respect for those athletes who train and repeatedly put themselves through a gruelling regime in these true contact sports.
Adam Taylor does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
