Physiology of a Groin Injury
Manchester United's Joe Jordan is stopped with a kick in the groin by goalkeeper Ray Clemence of Liverpool in 1979.
Credit: Manchester Daily Express / Getty Images

Here's an obvious fact: Groin kicks are horrendously painful. The nausea, tears, and collapse might seem like overkill, but they are actually ways your body is trying to improve the situation. "This is essentially a defense mechanism by the body to reduce the painful sensation," says Dr. Muhammad A. Mirza, founder of erectiledoctor.com. The details of your physiological response to a groin kick might be the last thing on your mind when it happens, but knowing a little more about what your body’s doing could encourage you to prevent these kinds of injuries in the future and better address the ones that are inevitable.

When a man gets hit in the groin, his body goes a little crazy. Signals get launched up to his brain at about 265 mph, giving it notice that something’s wrong. A neurotransmitter called Substance P is also released by the testicles to indicate the need for pain relief.

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The signals that reach the brain trigger several processes. Endorphins – our body's natural pain relievers – are released to mask some of the hurt. Unfortunately, higher levels of endorphins cause a drop in oxygen levels, which can lead to a pounding headache and nausea. For some men, a part of the brain called the cervical sympathetic ganglia is also activated, resulting in tearing up or crying. The inner ear may get in on the action too, creating a change in fluids that results in dizziness. In addition to all of this, the brain is simultaneously sending signals back down to the groin and abdominal area to let you know you’re in pain down there.

Signals are sent to the abdominal region because that area shares pain receptors with the groin. Some of these signals are what make you want to grab your stomach, bend over, or lie on the ground in the fetal position. The abdominal pain, paired with possible nausea and dizziness, can sometimes cause vomiting. Increased heart rate, sweating, and higher body temperature are other common responses to this kind of injury. Basically, your body is going insane, all probably an attempt to tell you to never get hurt like that again. "From an evolutionary perspective our bodies are designed to react very intensely to any kind of trauma in that particular anatomy," says Mirza. (Remember that next time you’re folded over and ready to vomit.)

While trauma to your family jewels is going to be painful no matter what, there are a few steps you can take after the fact to reduce the effects:

1. Lay Down
Lying down flat on your back can reestablish proper blood flow to the brain, relieving headache and nausea and deactivating the sympathetic ganglia. This position can also help relax the groin ligaments and other muscles that were seizing up.

2. Hydrate and Cool Off
Moving to a cool place and hydrating is also important because all that tearing, sweating, vomiting, and the increase in body temperature can leave you low on fluids. Mirza also recommends over-the-counter pain relievers, particularly those that can help reduce inflammation, like acetaminophen.

3. See a Doctor If the Pain Persists
If the pain resulting from a groin injury is persistent, if there was serious nausea, vomiting, or fever, or if there are obvious signs of trauma – like bruising or swelling – it’s a good idea to seek medical attention. In serious cases, groin hits can cause testicular torsion (a twisting of the testicle), rupture, and can even threaten your fertility. This level of injury should be regarded as a medical emergency.

Of course, even better than any remedy is avoiding these injuries in the first place. Although you’ve probably survived plenty of nut shots in the past, it’s not something to take lightly. This means that, if you’re playing a sport or doing any activity that could lead to a forceful strike below the belt, be smart and wear a cup. You might think it’s awkward or uncomfortable, but it’s really nothing compared to what you could face otherwise.