Real-Life Stress and Opioid-Mediated Analgesia in Novice Parachute Jumpers

Abstract

Abstract It was investigated whether a stress-induced analgesia could be demonstrated in human subjects (N = 24) performing a first-time parachute jump. Sensitivity for electrical stimulation and pressure pain was measured at several moments before and after the jump. The opioid antagonist naloxone or saline placebo was administered immediately after the jump to examine possible opioid-mediated effects. After the jump, the placebo group showed a lower pain sensitivity than the naloxone group, with the latter returning to pretest levels, consistent with an opioid-mediated analgesia. Although analgesic effects appear to have been initiated prior to the jump, plasma β-endorphin showed a sudden large increase immediately after the jump. This increase correlated with reports of anxiety and loss of control during the jump, and was associated with reduced pain sensitivity. Despite several limitations, this study suggests that the real-life stress of a parachute jump may attenuate pain through endogenous opioid release.