If onset is fast, the duration of rigor mortis is:

• A. Short
• B. Long
• C. Moderate
• D. Variable

Answer: (A)

Rigor mortis timing is driven by temperature affecting the rate of chemical changes in muscles. When heat speeds up the onset of rigor, it also speeds up the subsequent processes that resolve it, so the stiffening period doesn’t last long. In warmer conditions, onset is rapid and the duration is shortened; cooler conditions slow the start and extend how long the stiffness remains. So if onset is fast, the duration tends to be short.