Generally speaking, zombies in popular culture take on one of two forms: 1) the slow, lumbering zombie, or 2) the fast, agile zombie. Each holds certain dramatic advantages for the filmmaker, but which is a better representation of the reality of zombiism as manifested in actual human beings? One prominent theory is that it’s both.
Rigor mortis begins to take hold about 3 hours after death, and lasts about 48 hours. It follows a clear progression and regression curve, with full rigor being gradually reached at the 24 hour mark, then dissipating at the same rate until completely gone.
It is widely believed that the undead deteriorate much more slowly than the simply dead, due to chemical reactions in the brain and body that have a result similar to embalming fluid. But, deterioration does happen. Therefore, the time frame for onset and resolution of rigor may be delayed in a zombie, but it will surely occur. So one theory of zombie ambulatory speed is this:
- When a zombie awakens immediately after death it shows no sign of stiffness, and is as fast as it was in life.
- As rigor mortis begins to take hold, the zombie gradually slows to a shamble – the “classic” zombie gait.
- Once the zombie reaches the height of rigor it is completely stiff, lying on the ground and unable to move.
- As the stiffness subsides the zombie rises and begins shambling as it did during the rigor progression.
- At the resolution of rigor the zombie is again able to move as fast as if it just died, with no stiffness whatsoever.
If this theory holds true, be prepared to face zombies of all shapes, sizes, and speeds.