Study of testosterone reactivity and its variance in response to skydiving

The purpose of this study was to examine whether the sex hormone testosterone was reactive to an exciting, potentially life threatening situation: skydiving from 14,000 feet. Participants included 32 males and 12 females who provided repeated saliva samples before and after jumping as well as on a baseline day. Hierarchical Linear Modeling was used for statistical analysis. Testosterone was highly stable within an individual, x2(29)=1198.8, p\u3c.0001, with 88.75% of the total testosterone variance due to between individual differences. Testosterone showed momentary changes as well. Testosterone changed dramatically in response to skydiving, rising from the start of the experiment until the jump, B=.10, p\u3c.0001, and then declining significantly after the jump, B=-.10, p\u3c.007. Overall, testosterone was not different between jump and basal days, B=.03, p=.74, but there was substantial variation in the basal-day effect, suggesting some individuals had higher while others had lower testosterone on the jump day compared to basal testosterone, x2(29)=221.06, p\u3c.0001. Males had significantly higher testosterone levels, B=-1.09, p\u3c.0001, and showed greater testosterone reactivity than females, B=-.07, p\u3c.025. In conclusion, the sex hormone testosterone changes dramatically in response to an exciting situation like skydiving. These changes are observed despite the overall stability in testosterone from one individual to another. Findings contrast with a previous study that found salivary testosterone was significantly lower on a jump day and were especially low prior to skydiving (Chatterton, Vogelsong, Lu & Hudgens 1997), but fit with an emerging perspective of testosterone as reactive to an individual’s social context