Hysterical strength refers to a display of extreme physical strength by humans, beyond what is believed to be within their capacity, usually occurring when people are in — or perceive themselves, or others, to be in — life-or-death situations. It was also reported to be present during situations of altered states of consciousness, such as trance and alleged possession. Its description is mostly based on anecdotal evidence. The name refers to hysteria, a nosological category that included bouts of superhuman strength as one of the possible symptoms, but in Europe this had also been an attribution in previous cases of alleged demonic possession. Charcot imputed to the phase of hysterical attacks called clownism the presence of strength and agility not consistent with the age and sex of the person, which before in the Catholic ritual of exorcism was attributed to demonic force. Thus, the cause of the phenomenon began at that time to be addressed by the investigation of insanity. During that period in the 19th century, the term hysterical strength could also be found in the intersection of such fields, scientific and religious, for instance appearing in a statement by a physician for the Society for Psychical Research. It was also described in reports of trance or possession in several other cultures, as for example in the New Testament (Mark 5:4) or in shamanic practices. Unexpected strength is claimed to occur during excited delirium.

Examples

The most common anecdotal examples based on hearsay are of parents lifting vehicles to rescue their children, and when people are in life-and-death situations. Periods of increased strength are short-lived, usually no longer than a few minutes, and might lead to muscle injuries and exhaustion later. It is not known if there are any reliable examples of this phenomenon.

Research

Early experiments showed that adrenaline increases twitch, but not tetanic force and rate of force development in muscles. One proposed explanation is Tim Noakes' "central governor" theory, which states that higher instances in the central nervous system dynamically and subconsciously control the number of active motor units in the muscle. Normally, in order to guarantee homeostasis, the entire motor neural capacity is not activated and, therefore, the total capacity of the muscle during performances outside of an emergency situation remains inaccessible: this would lead to exhaustion of energy resources and even physical injuries. However, in life-threatening situations, it is adaptive for the central governor limits to be removed or modified. People in high load weightlifting training are able to activate more motor units, which ensures more strength and efficiency in muscle contraction, even though they had the same amount of muscle mass compared to people in low load training. Exercise physiologist Robert Girandola has pointed out that most cars have a 60/40 weight distribution, as the engine block puts the center of mass slightly towards the front of the car. In most instances, the individual is lifting one or two wheels of the car from the back. Therefore, they are only actually lifting a small fraction of the vehicle's weight. While the fight or flight response allows for increased lifting capacity, it would be hundreds of pounds rather than thousands.