The TV show Sports Science tested the choking strength between MMA legend Fedor Emelianenko and a Burmese Python.

The Burmese python (Python bivittatus) is one of the five largest species of snakes in the world (about the third-largest as measured either by length or weight). It is native to a large variation of tropic and subtropic areas of South and Southeast Asia.

Constriction is a method used by various snake species to kill their prey. Although some species of venomous and mildly venomous snakes do use constriction to subdue their prey, most snakes which use constriction lack venom. The snake initially strikes at its prey and holds on, pulling the prey into its coils or, in the case of very large prey, pulling itself onto the prey. The snake will then wrap one or two coils around the prey. The snake will monitor the prey’s heartbeat to ascertain when it is dead.

Contrary to myth, the snake does not crush the prey, or break its bones. Also, contrary to previous belief, the snake does not cause suffocation by constricting the victim. Instead, a study of death caused by boa constrictors, showed that constriction “shuts off” blood flow (and therefore oxygen) needed by vital organs such as the heart and brain, which would lead to unconsciousness and death very quickly – in seconds – in other words, constriction can interrupt blood flow and overwhelm the prey’s usual blood pressure and circulation.

Artery pressure drops, vein pressure increases, and blood vessels begin to close. The heart does not have enough strength to pump against the pressure and blood flow stops. Internal organs with high metabolic rates, including the brain, liver, and the heart begin to stop and die due to ischemia, a loss of oxygen and glucose. There is evidence that boa constrictors have more difficulty killing ectotherms, animals like lizards and snakes that rely on external heat to regulate their body temperatures. A boa constrictor was observed attacking a spinytail iguana for an hour, and the iguana survived.