- The time of onset of rigor can vary a certain amount according to two main factors: the pH of the muscle at the moment of death (determined by activity prior to death) and the amount of glycogen present in the muscle (linked to pH of the muscle)
- The internal and environmental temperatures also play a part - a higher temperature increases the rate of glycolysis, which results in a shorter interval between death and onset of rigor and in an increase in muscle shortening
7) Other factors
- Rigor mortis develops quicker at higher temperatures and is affected by the decedent’s activity prior to death. A higher internal body temperature causes more lactic acid to be produced, which accelerates the development of rigor
- Accelerated rigor can also be found in some drug-related deaths as certain substances (for example cocaine, PCP and methamphetamine) can cause higher internal body temperatures even if the environmental temperature is not raised
- Physical activity before death also causes accelerated rigor due to a higher internal body temperature and increased lactic acid production
Bate-Smith, E. C., Bendall, J. (1949) Factors Determining the Time Course of Rigor Mortis. J. Physiol. 110, pp 47-65.
Bendall, J. R. (1951) The Shortening of Rabbit Muscles During Rigor Mortis: IT’s Relation to the Breakdown of Adenosine Triphosphate and Creatine Phosphate and to Muscular Contraction. J. Physiol. 114, pp 71-88.
Dix, J., Graham, M. (2000) Time of Death, Decomposition and Identification: An Atlas. Florida: CRC Press.
Gunn, A. (2009) Essential Forensic Biology. West Sussex: Wiley Blackwell.