Putting The Flight In “Fight-Or-Flight”

Many people love a “rush” – lines for good rollercoasters are rarely short. Some people really love a rush and do things like skydiving, base-jumping or climbing mountain cliffs “free solo” without safety lines. Unfortunately, some people get that rush from criminal activity, antisocial behavior, or drugs. These people are high on the personality trait, sensation-seeking, where people display an affinity for novel, intense, and exciting experiences and a willingness to take risks in order to engage in these types of experiences ranging from extreme sports/activities.

But where does that “rush” come from, and why do some people find intense, exciting experiences more pleasurable than others? One potential source of the “rush” is testosterone reactivity. Rapid changes in testosterone levels have been observed in challenging or exciting situations. For example, testosterone levels rise after winning a competition. Surprisingly, testosterone changes in response to skydiving have not been investigated much, and it was not clear at the outset of this study if testosterone would be reactive to skydiving. Stress biomarkers like cortisol and autonomic biomarkers of the “fight or flight” system skyrocket following skydiving because many extreme activities are also intensely stressful events. It is possible that stress helps feed the rush, and it may work with testosterone to heighten the thrill and excitement of skydiving.

How was the study conducted?

Forty-four participants were recruited from customers of a recreational skydiving facility and included both experienced skydivers (34%) and first-time skydivers. All participants provided multiple saliva samples in the time leading up to boarding the plane, immediately before boarding the plane, immediately upon landing, 15 minutes after landing and 60 minutes after landing. Testosterone and cortisol levels were assayed from the saliva samples. Participants also wore a cardiac monitor strapped to their chest during the jump to measure autonomous nervous system activity, including heart rate and a measure of heart rate variability called RMSSD. Participants gave additional saliva samples to establish how hormones change on a typical day.

What did the study find?

Testosterone levels rose in response to the jump day in 93% of participants, even people who had jumped hundreds of time before. This rise in testosterone in response to skydiving was substantially greater than the baseline day. While males had higher overall levels of testosterone, both males and females showed equivalent testosterone reactivity, which amounts to a much larger proportional testosterone rise within females. Participants who described themselves as sensation-seekers showed greater testosterone reactivity to skydiving.

Separately from sensation seeking, the participants who showed the greatest stress response also showed the largest testosterone responses to skydiving suggesting that the stress heightens the challenge of a jump. This was true for all three stress biomarkers including cortisol, sympathetic arousal indexed by heart rate and parasympathetic arousal indexed by heart rate variability. Interestingly, the reactivity of each biomarker was independently associated with testosterone reactivity, suggesting an additive thrill effect from each aspect of physiological arousal.

Why are these findings important?

There are three important takeaways from this study. First, nearly all participants showed a rise in testosterone, suggesting this biomarker may instantiate some of the excitement and thrill of skydiving and possibly other sensation-seeking activities.

Second, equivalent testosterone reactivity was seen in both men and women. In some previous work, men, but not women, showed testosterone reactivity. However, these studies looked at competitions, like video games, that might be more engaging for men than women. When selecting for participants who seek out the chance to free-fall from 14,000ft above the earth, both women and men, as well as novice or experienced skydivers, showed similar testosterone reactivity.

Third, testosterone reactivity was heightened by stress reactivity, so it appears that the feeling of a “rush” comes from multiple biological mechanisms. Some previous work has found cortisol inhibits testosterone, and vice versa, such that situations that are positive and challenging would lead to high testosterone and low cortisol. For sensation-seekers, skydiving is arguably both challenging and stressful, causing increases in testosterone and cortisol.

Ours is one of the first studies to discover that autonomic arousal characteristic of a “fight or flight” response also heightened testosterone reactivity. In sum, our study shows that testosterone is reactive to skydiving, and testosterone and stress biomarkers can work in tandem during skydiving to help put the flight in fight-or-flight.

These findings are described in the article entitled Putting the flight in “fight-or-flight”: Testosterone reactivity to skydiving is modulated by autonomic activation, recently published in the journal Biological Psychology.