Hysterical strength is a display of extreme strength by humans, beyond what is believed to be normal, usually occurring when people are in life-and-death situations. The classic anecdotal example is of parents lifting vehicles to rescue their trapped children. The extra strength is commonly attributed to increased adrenaline production, though supporting evidence is scarce, and inconclusive when available. Research into the phenomenon is difficult, though it may be possible as adrenaline is known to affect muscle twitch and endurance.
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. Hysterical strength can also be observed among mentally ill. Period of increased strength is short-lived, usually no longer than few minutes, and might lead to muscle injuries and exhaustion later. It is not known if there are any reliable scientific examples of this phenomenon.
- Before May 1962, Jack Kirby claims a woman lifted a car off her baby, which inspired him to create the Hulk.
- In 1982, in Lawrenceville, Georgia, Tony Cavallo was repairing a 1964 Chevrolet Impala automobile from underneath when the vehicle fell off the jacks on which it was propped, trapping him underneath. Cavallo's mother, Mrs. Angela Cavallo, lifted the car high enough and long enough for two neighbours to replace the jacks and pull Tony from beneath the car.
- In 2006, Ivujivik, Quebec, resident Lydia Angiyou saved several children by fighting a polar bear until a local hunter shot it.
- In 2006, in Tucson, Arizona, Tom Boyle watched as a Chevrolet Camaro hit 18-year-old Kyle Holtrust. The car pinned Holtrust, still alive, underneath. Boyle lifted the Camaro off the teenager, while the driver of the car pulled the teen to safety.
- In 2009, in Ottawa, Kansas, 1.70 m (5 ft 7 in), 84 kg (185 lb) Nick Harris lifted a Mercury sedan to help a 6-year-old girl pinned beneath.
- In 2009, in Newport, Wales, Donna McNamee, Abigail Sicolo, and Anthony McNamee lifted a 1.1 ton Renault Clio off an 8-year-old boy.
- In 2011, in Tampa, Florida, 1.91 m (6 ft 3 in), 134 kg (295 lb) University of South Florida college football player Danous Estenor lifted a 1,600 kg (3,500 lb) car off a man who had been caught underneath. The man was a tow truck driver who had been pinned under the rear tire of a 1990 Cadillac Seville, which had lurched forward as he worked underneath it. The man suffered only minor injuries.
- In 2012, in Glen Allen, Virginia, 22-year-old Lauren Kornacki rescued her father, Alec Kornacki, after the jack used to prop up his BMW slipped, pinning him under it. Lauren lifted the car, then performed CPR on her father and saved his life.
- In 2012, in Michigan, Austin Smith (age 15) lifted a car to save his grandfather pinned underneath 
- In 2013, in Oregon, teenage sisters Hannah (age 16) and Haylee (age 14) lifted a tractor to save their father pinned underneath.
- In 2013, in Salvage, Newfoundland and Labrador, Cecil Stuckless, a 72-year-old man lifted a Jeep to save his son-in-law pinned underneath 
- In 2015, in St. John's, Newfoundland, Nick Williams lifted a four-wheel-drive vehicle to save a young boy pinned beneath its tire.
- In 2017, in Temple Terrace, Florida, Kenny Franklin, lifted an SUV from a state trooper after an accident 
- In 2019, in Ohio, Zac Clark, a 16-year-old football player, lifted a 3,000 lb car when he heard his neighbor call for help.
Hysterical strength can result in torn muscles due to higher mechanical stress.
Early experiments showed that adrenaline increases twitch, but not tetanic force and rate of force development in muscles. It is questionable whether adrenaline, released from the adrenal medulla into the venous circulation, can reach the muscle quickly enough in order to be able to cause such an effect in the midst of a crisis. It may be that norepinephrine released from sympathetic nerve terminals directly innervating skeletal muscle has more of an effect over the timescale of seconds.
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- Rizvi, Mudassir Haider; Abdul Azeem, Muhammad; Savanur, Arifa (1 December 2019). "Effects of adrenaline on contractility and endurance of isolated mammalian soleus with different calcium concentrations". Journal of Muscle Research and Cell Motility. 40 (3): 373–378. doi:10.1007/s10974-019-09551-9. ISSN 1573-2657. PMID 31444710. S2CID 201282977.
- "White Paper Report on Excited Delirium Syndrome" Archived 11 October 2010 at the Wayback Machine, ACEP Excited Delirium Task Force, American College of Emergency Physicians, 10 September 2009
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one of the Hulk comic books' artists, Jack Kirby, has said he was inspired by seeing a woman rescue her child from beneath a trapped car.
- Groth, Gary (23 May 2011). "Jack Kirby Interview - Part 6". The Comics Journal.
KIRBY: The Hulk I created when I saw a woman lift a car. Her baby was caught under the running board of this car. The little child was playing in the gutter and he was crawling from the gutter onto the sidewalk under the running board of this car — he was playing in the gutter. His mother was horrified. She looked from the rear window of the car, and this woman in desperation lifted the rear end of the car.From The Comics Journal #134 (February 1990)
- Lipstak, Andrew (30 August 2015). "The Incredible Hulk Was Inspired By A Woman Saving Her Baby". Gizmodo.
Jack Kirby witnessed a woman lift a car to get her child out from under it. The moment helped inspire one of his most famous creations: the Incredible Hulk.
- Clark, Josh. "How can adrenaline help you lift a 3,500-pound car?", 11 December 2007. HowStuffWorks.com. Retrieved 13 November 2008.
- Jane George (17 February 2006). "Polar bear no match for fearsome mother in Ivujivik". Nunatsiaq News / Nortext Publishing Corporation (Iqaluit). Archived from the original on 27 September 2007. Retrieved 1 January 2009.
- Huicochea, Alexis. "Man lifts car off pinned cyclist", Arizona Daily Star, 28 July 2006. Retrieved 21 November 2010.
- Associated Press. "Kansas dad somehow lifts car off 6-year-old girl", 18 December 2009. news.yahoo.com. Retrieved 19 December 2009.
- "Neighbours help lift car off boy". 4 June 2009. Retrieved 20 October 2018.
- Greg Auman (24 June 2011). "USF Bulls offensive lineman Danous Estenor lifts car to free trapped man". St. Petersburg Times (Tampa Bay, FL).
- Newcomb, Alyssa (August 2012). "Superhero Woman Lifts Car Off Dad - ABC News". ABC News. Retrieved 12 January 2016.
- "Boy's strength muscles car off grandpa, saves life". Deseret News. 4 March 2012.
- "Oregon man pinned under 3,000-pound tractor saved by teen daughters". Fox News. 11 April 2013. Retrieved 12 January 2016.
- "Septuagenarian Superhero? Man Lifts Car Off Son-In-Law". NPR. 22 July 2013.
- "Shea Heights hero finds strength to lift vehicle off injured boy". CBC News. 28 September 2015. Retrieved 28 September 2015.
- "Passenger lifts SUV, rescues Florida trooper after Uber driver has medical emergency". Tampa Bay Times. Retrieved 20 October 2020.
- "Ohio high school football player lifts car to save neighbor's life".
- "This 16-year-old football player lifted a car to save his trapped neighbor".
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- Grassi, C; Passatore, M (February 1988). "Action of the sympathetic system on skeletal muscle". Italian Journal of Neurological Sciences. 9 (1): 23–8. doi:10.1007/BF02334403. PMID 2965685. S2CID 25661287.