Protecting your internal organs from power shots is equally as important as protecting your chin. Here Dr Rosi Sexton kicks off a series of medical features regarding protecting your insides from the outside…

Where are they? 

Your kidneys are two fist-sized organs, each shaped like a bean.

They reside either side of the spine, just below the rib cage. 

WHAT DO THEY DO?

The main function of the kidneys is to filter the blood and to regulate what is in your circulatory system. They eliminate waste products, control blood pressure, and balance levels of electrolytes (salts). 

The kidneys also release several hormones, including erythropoietin which stimulates the formation of oxygen carrying red blood cells and is crucial to the body’s ability to adapt to endurance training. 

WHAT DAMAGE DOES BLUNT TRAUMA DO?

The kidneys are a legal target in an MMA fight - the only type of kidney strikes that are banned by the Unified Rules are heel kicks (presumably from guard).

Although they are somewhat protected by the ribs, strikes landing to the back of the body either side of the spine can cause damage to the kidneys. They are particularly vulnerable to knees to the body when the fighter is turtled up on the ground. It’s also possible, though rare, for the kidney to be damaged in a bad landing from a throw or slam. 

Blood in the urine is a very common sign of injury to a kidney. A large amount of bleeding may turn the urine an unmistakable red or brown color; smaller quantities of blood may give it a more subtle pink tinge. Other symptoms of damage may include back pain, abdominal pain or difficulty in passing urine. There may be visible swelling or bruising in the area. 

If damage is suspected, then it’s important for the fighter to be evaluated by a doctor. Depending on the history of the injury and the symptoms, she or he may decide to perform further tests or imaging, such as a CT scan. 

Fortunately, in most cases of blunt trauma to the kidney, the damage is relatively minor.

This type of low-grade kidney injury is sometimes referred to as a “bruised kidney.” And usually the organ will recover by itself with bed rest. It is important for the fighter to be monitored during this time in case of complications. The bad news is that impact is not the biggest danger to a fighter’s kidneys. 

WHAT ABOUT DEHYDRATION AND WEIGHT CUTTING?

As MMA has become increasingly competitive over the last decade, the practice of weight cutting has grown in popularity.

This is where a fighter uses various techniques to reduce his or her weight temporarily for the weigh-in, and then aims to regain much of that weight before the fight.

One of the most common strategies for short-term weight loss is dehydration.

Fighters often restrict their fluid intake over the 24–48 hours prior to the weigh-in, and many use saunas and/or exercise to dehydrate themselves further. 

Studies have shown that intense exercise temporarily reduces kidneys function. This is generally normal, healthy and quickly reversible.

Part of this process is a reduction in blood flow to the kidney, which is normally compensated for by other changes that take place. 

When an athlete becomes dehydrated. However, the blood flow to the kidney drops still further. Take this too far and the kidneys may stop functioning or become damaged, and acute kidney injury (also known as ‘acute renal failure’) can set in.

Warning signs include dry mouth, low urine output and lethargy things that many fighters regard as normal when cutting weight.

Symptoms of renal failure include nausea, shortness of breath, drowsiness, confusion, pain in the back and chest pain.

As it becomes more severe, there may be swelling in the legs, and even seizures or loss of consciousness. 

Taking non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen, diclofenac or naproxen medicines which are commonly used by fighters for management of minor injuries in the run up to a fight – can dramatically increase the risk of kidney failure in the presence of dehydration. 

Kidney failure caused by dehydration is treated by giving intravenous fluids.

Sometimes this will be enough to allow the kidneys to recover; other times dialysis may be needed. 

Depending on how much permanent damage has been done, some people will go on to have chronic kidney disease.

In mild to moderate cases, the kidneys can adapt so there may not be any noticeable symptoms. Severe cases may eventually need long term dialysis or a kidney transplant. 

Weight-cutting, when done badly, can be one of the most dangerous aspects of MMA. Fighters should make sure that they understand the process and the risks involved. 

ARE YOU AT RISK?

There’s no such thing as ‘safe’ dehydration. However, people with existing kidney disorders may be at a greater risk. If you have had problems with your kidneys in the past, or you are in a high risk group for developing kidney disease (for example, diabetics) then you should speak to your doctor before competing in MMA, and especially before attempting to cut weight. 

Certain performance enhancing drugs may also increase the risk. Diuretics that increase the amount of urine produced are sometimes misused by fighters attempting to drop large amounts of water weight. Their use may increase the risk of kidney damage during the weight cutting process.

Anabolic steroid use has also been shown to cause scarring and loss of function within the kidneys, especially over the long term.

Both anabolic steroids and diuretics are banned by the athletic commissions that regulate MMA in the US. 

NOTABLE CASES

1) Kevin Randleman

In 2007 Kevin Randleman was hospitalized with severe kidney damage. Previously, he’d had his license revoked by the Nevada State Athletic Commission after submitting a fake urine sample for a drugs test.

Fans speculated that this was due to steroid use, although he denied that was the reason for the deception.

2) Houston Alexander

UFC veteran Houston Alexander donated one of his kidneys to his eldest daughter in 2000 to save her life when her own failed.

Although he’d never had any problems as a result of the missing kidney, and had always passed his pre-fight medical tests, the New Jersey Athletic Control Board threatened to stop his fight against Thiago Silva at UFC 78 just one hour before it was due to take place.