The turtle position is a common position in Brazilian Jiu-Jitsu, Judo, wrestling, and other martial arts where you are belly-down on all-fours, potentially with an opponent's weight on top. In particular, you are generally curled in very tightly with the arms and legs, almost like a fetal position, to prevent an opponent from reaching underneath and accessing your arms and legs on the vulnerable front side of your body. You are essentially using your back and outside as if it was a proverbial turtle retreating into its shell to deter an attacking predator.

The turtle position is effective in grappling arts where striking is not allowed, or even in striking sports where strikes to the back of the head or spine are disallowed, so that the back can be treated like armor. You can then wait for the opponent above or nearby to put something within reach to grab and attack, which is sometimes referred to as the concept of the "snapping turtle".

This strategy, unfortunately, falls apart in non-sport contexts where strikes to the back of the head and spine are allowed. Striking such areas can quickly deliver devastating and crippling injuries, unless wearing actual armor (such as European or Japanese historical types), which is exactly why it is generally disallowed in various modern combat sports where people are unarmored. Autonomic functions such as the heartbeat and breathing are localized to the backside of the brain, so harming this area of the body is extremely dangerous.

When weapons are involved, the turtle position, like a fetal position, may have some utility again as it prevents certain vulnerability inside targets of the body (such as the face, organs, or arteries) from being cut, stabbed, or struck, which might sometimes be working then leaving somewhat less vulnerable portions of the body on the backside exposed.

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