To conduct a study on the effects that a bungee jump might have, 20 volunteers who had never done bungee jumping before took the plunge at 60 m up at the Onze Lieve Vrouwe Gasthuis hospital in Amsterdam.

“The study site was located at the hospital grounds, where a crane was placed. Bungee jumps took place from an altitude of 60 m, under supervision and guidance from an experienced commercial bungee jump crew. On the morning of the study day, an intravenous access catheter was placed in the cubital vein [upper arm].“

Half of the volunteers had been previously treated with a three-day course of propranolol (a beta blocker), while the control group was not. Subsequent blood analyses showed that many of the volunteers who jumped showed obvious signs of stress before jumping, and so further studies might be needed to determine whether the immune system effects were caused by mental strain or by the physical stresses of the jump, or both.

(Link: improbable.com, Photo of Bungee by Mishimoto, some rights reserved)