After finishing off another great day of downhill skiing, a 70-year-old man steps into his car.He should be exhausted, especially given the eight hours of abuse he just inflicted upon his body.Instead, he screams at the top of his lungs, "I LOVE IT!!!" and rides that rush of excitement for the duration of the drive home.
This anecdote isn't made up – it was a very real occurrence when skiing with a friend's grandfather, and if the other passengers in the car were unaware of this behavior, it might scare the bejeezus out of them. What pushes an elderly man to act in such a way? And how does he continue to behave like a man half his age?
Grandpa Z was riding an adrenaline rush.
We've all been there, and we're all familiar with the terminology. Maybe it wasn't from skiing, but that surge of energy might have been the product of another sport, finishing out a running race or completing another seemingly-inconceivable challenge. The adrenaline rush is a very real thing, with very real science behind it.
Adrenaline is a hormone that accelerates the breakdown of sugar in the liver to provide fast-acting energy to be used during moments of stress. While sports may not seem like "stress," digging deep into your person for one final burst of energy certainly creates such an effect. Originally discovered in 1915 by biochemist Earl Sutherland, adrenaline was found to latch itself onto a receptor on a cell's surface, which triggers the cell to send out signals to jumpstart its metabolism. This activity stimulates the cells, which causes a ripple effect, stimulating the body as a whole (McMurray 1995).
The adrenaline rush you may experience causes real physiological changes in the body, which can alter muscle contractions (Marsden et al 1970). In addition to muscular effects, adrenaline also tells the brain to pump the heart faster. This increased cardiac output supplies more oxygen to muscles, allowing for the muscles to behave in the most efficient capacity (MedlinePlus 2012). The stories of people gaining superhuman strength – to fight free from a burning care, for example – are based in reality, as people really can perform incredible activities under the right circumstances.
Adrenaline, notably, is also used in injection form to treat some life-threatening allergic reactions. Epinephrine is in a class of medications called alpha- and beta-adrenergic agonists, the injectable form of the hormone. But before you think that adrenaline injections can act as a performance-enhancer, scientific studies have found that taking injections of the hormone do not translate into enhanced athletic capabilities (Davis et al 2008). Similarly, artificially triggering the "fight or flight" human response could ultimately prove to be detrimental, as cell receptors receiving adrenaline can become desensitized. Too much adrenaline in the bloodstream, too, can lead to heart failure, according to research from the NIH (Boynton 2012).
Before swearing off adrenaline as a wholly bad thing, remember that these issues come about largely from artificially triggering the body's hormones. Instead, make like Grandpa Z, and stick with more organic ways of achieving that rush.
Boynton, E. (June 7, 2012). "Doubling down on heart failure: researchers discover new route to disease, and drugs to match." University of Rochester Medical Center: News. Retrieved from http://www.urmc.rochester.edu/news/story/index.cfm?id=3532.
David, E., Loiacono, R., Summers, R. (May 26, 2008). "The rush to adrenaline: drugs in sport acting on the β-adrenegic system." British Journal of Pharmacology vol. 154 (3):584-597. Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2439523/.
Marsden, C., Meadows, J. (April 1970). "The effect of adrenaline on the contraction of the human muscle." Journal of Physiology vol. 207 (2):429-448. Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1348716/.
McMurrya, E. (1995). "Anatomy of an adrenaline rush." Notable 20th Century Scientists. Retrieved from http://news.sciencemag.org/1999/11/anatomy-adrenaline-rush.
MedlinePlus. (December 9, 2012). "Epinephrine and exercise." MedlinePlus. Retrieved from http://www.nlm.nih.gov/medlineplus/ency/anatomyvideos/000051.htm.