The activator is a handheld spring-loaded instrument which delivers a small impulse to the spine. It gives no more than 0.3 J of kinetic energy in a 3-millisecond pulse and the aim is to produce enough force to co-activate mechano-receptors in the vertebrae, but not enough to cause harm. It is extremely gentle and safe to use even in the elderly, where osteoporosis may be present.
 Fuhr, Arlan W.; J. Michael Menke (February 2005). “Status of Activator Methods Chiropractic Technique, Theory, and Practice”. Journal of Manipulative and Physiological Therapeutics 28 (2): e1–e20. doi:10.1016/j.jmpt.2005.01.001. PMID 15800504. http://linkinghub.elsevier.com/retrieve/pii/S0161475405000023. Retrieved 2008-08-18.