What Your Body Thinks of Bungee Jumping

How Extreme Sports Affect Hormone Levels

Man bungee jumping
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Extreme sports are becoming increasingly popular. In an article titled “Extreme sports are good for your health: A phenomenological understanding of fear and anxiety in extreme sport,” Brymer and Schweitzer define extreme sports “as independent leisure activities where the most likely outcome of a mismanaged mistake or accident is death.”

Limited research has been done elucidating hormonal stress responses to extreme sports.

Furthermore, it’s unclear what effects extreme sports have on long-term health. Nevertheless, let’s take a look at a handful of studies that do explore the endocrine reactivity of extreme sports.

Bungee Jumping

In a 2014 study titled “Acute Stress Elicited by Bungee Jumping Suppresses Human Innate Immunity,” van Westerloo and colleagues found that bungee jumping increased levels of cortisol and catecholamines.

Catecholamines refer to neurohormones, which are important in stress responses. High levels of catecholamines can lead to increased blood pressure, headaches, sweating, heart pounding, chest pain, and anxiety. Dopamine, epinephrine (adrenaline), and norepinephrine (noradrenaline) are all catecholamines.

The goal of this study, however, was to determine whether an acute stress response—bungee jumping—suppressed key inflammatory responses involved when the immune system responds to infection.

In other words, the researchers examined the ability of white blood cells (leukocytes) to secrete inflammatory mediators and digest bacteria (i.e., release cytokines and phagocytose, respectively).

To this end, the researchers pretreated half of the bungee jumpers with propanol, which is a beta-blocker, thus blunting the effects of catecholamines on the immune system.

They found that immune suppression caused by stress is independent of catecholamines. Interestingly, although the observed leukocyte count increased during the study, these leukocytes were less responsive.

Instead of immunosuppression mediated by catecholamines, it appears that after an acute stress event glucocorticoids such as cortisol suppress the immune system through nongenomic mechanisms that are faster than the transcription of DNA. These nongenomic mechanisms are also responsible for the immediate relief experienced by people with allergies who take glucocorticoids like prednisone.

Finally, other research shows that skydiving result in an increase in endorphins. This increase in endorphins causes a “rush” or “high.”

Rock Climbing

Types of Rock Climbing

In technical free rock climbing, the manner that the climber ascends is of cardinal importance. During a clean ascent, the climber performs each move without assistance—there is no hanging, falling, or pulling on equipment for advantage.

In lead climbing, the climber clips the rope into points of protection during the ascent thus performing a clean ascent. Alternatively, top rope climbing involves a rope that is anchored at the top of the climb.

This rope can be used to assist during the climb. In both forms of rock climbing, the rope protects the climber from falling.

Lead climbing is more difficult than top rope climbing. Lead climbing is also more highly regarded by avid rock climbers. Top rope climbing is practiced by beginners as well as experienced climbers during practice.

Hormonal Response

In a study titled “Hormone responses to a continuous bout of rock climbing in men,” Sherk and co-authors measured the levels of testosterone, growth hormone, and cortisol in 10 young male rock climbers as they climbed laps on a 55° vertical climbing route for 30 minutes.

Notably, the climb was top rope.

Participant rock climbers were at least of an intermediate skill level, apparently well-conditioned, and devoid of uncontrolled hypertension or asthma. The climbers were also not taking corticosteroid medications..

The researchers found that rock climbing transiently elevated plasma testosterone and growth hormone levels but there was no change observed in cortisol levels. Testosterone and growth hormone help drive the synthesis of lean muscle, and cortisol promotes the breakdown of protein. Furthermore, growth hormone and cortisol levels increase during strenuous exercise.

With the exception of no change in cortisol levels, the results of the current study concur with previous research. According to the authors:

Testosterone, cortisol, and GH [growth hormone] have all been shown in numerous studies to increase after bouts of resistance training and aerobic exercise in men, with hormone levels and magnitude of response depending on factors such as subject age, feeding and training status, and exercise intensity and duration.

The researchers suggest that the climbers experienced increases in catecholamines like adrenaline. During the climb, the climbers experienced an increase in anxiety proportional to the difficulty of the climb. Researchers also noted the following:

The duration of this protocol likely caused cardiovascular drift, potentially related to increased core temperature, likely increases in catecholamine levels, decreased stroke volume, or increased cardiovascular strain from the upper body component of the exercise.

Skydiving

It probably comes as no surprise that jumping out of an airplane with a parachute on is the ideal psychological stressor for scientific study. After all, skydivers brave the possibility of death for the rush of adventure.

Although skydiving is primarily a psychological experience, acceleration experienced during descent is a physical stressor, which alters blood flow and heightens plasma cortisol and catecholamine levels.

In a study titled “Hormonal Responses to Psychological Stress in Men Preparing for Skydiving,” Chatterton and colleagues recruited 26 volunteers to be assessed for psychological and hormonal responses during a first-time skydiving jump. The average age of the first-time skydivers was 26.4 years and all skydivers were in good health. In addition to this experimental group, a control group—which didn’t go skydiving—was also examined.

Here is how the skydivers physiologically reacted to the jump:

  • Increase in cortisol levels
  • Increase in catecholamine levels
  • Increase in prolactin levels
  • Increase in growth hormones
  • Increase in anxiety levels (peaked before jump)
  • Decrease in testosterone levels

Of note, cortisol, growth hormone, catecholamines, and prolactin are all stress hormones. These hormones are expected to increase proportionally to anxiety experienced and metabolic demand.

Caving

Caving goes by different names, such as spelunking and potholing. It involves exploring undisturbed cave systems. Caving enthusiasts must surmount steep inclines, water hazards, and tight squeezes. Although some spelunkers take issue with categorizing the pastime as an “extreme sport”—insisting that safety is a top priority—caving can be deadly.

Consider the following description of alpine potholing by Stenner and co-authors in a 2007 paper titled "Hormonal responses to a long duration exploration in a cave of 700 m depth”:

Unlike other extreme sports, in alpine potholing these stressors are present simultaneously. In fact, high skilled potholers generally move for 20 and more hours, almost without a break, wearing a climbing sit harness that compresses the lower limbs, in a cold and wet environment and, obviously, in darkness. On the basis of these specific characteristics of potholing, a marked stimulus of the HPA [hypothalamus-pituitary adrenocortical], HP [hypothalamus-pituitary] and HPT [hypothalamus-pituitary thyroid] systems could be expected, and in our experiment these responses have been investigated using the following parameters: serum growth hormone (GH), cortisol, thyroid-stimulating hormone (TSH), free triiodothyronine (FT3) and free thyroxine (FT4).

In this study, Stenner and colleagues examined the hormonal response to potholing among five elite potholers. These hormone fluctuations result from stimulating the HPA, HP, and HPT systems. The researchers found that cortisol, growth hormone, and free throxine levels all increased secondary to a 20-hour potholing excursion.

As expected, the results of this study highlight that the extreme physical and psychological stress of potholing altered hormone levels. Of note, the researchers hypothesize that the increase in free thyroxine occurred due to an increase in free fatty acids, which is normal during any long-duration endurance exercise.

What Do These Hormone Changes Mean for the Body?

In short, people who participate in extreme sports experience apprehension, anxiety, and fear. Stress hormones—including growth hormone, cortisol, prolactin, and catecholamines like adrenaline—are substantially increased during the activity. Typically, stress hormones rise proportionally to anxiety and metabolic load.

Even though these elevations in hormone levels are transient and hormone levels quickly return to baseline after completion of the sport, it’s unclear whether repeated exposure to extreme sports and continual fluctuations in stress hormone levels have long-term effects.

It’s also unclear whether extreme sports can exacerbate certain medical conditions or whether people with certain medical conditions should participate in extreme sports. Some experts suggest that those with chronic health problems should avoid extreme sports and that only people in good health should participate. Moreover, people with certain health conditions that can be exacerbated by stress—including uncontrolled hypertension, heart disease, and asthma—should eschew extreme sports. In fact, people with these conditions are screened and potentially excluded from extreme sports experiments.

A lot more research needs to be done before we truly understand the effects of extreme sports on the body. To date, most studies of extreme sports have focused on heart rate, energy expenditure, exercise utilization, and maximal oxygen consumption (VO2 max). Notably, VO2 max is a key indicator of fitness and endurance during exercise; it is a key metric among exercise physiologists.

If you have any questions about your health as it relates to extreme sports—or whether you should partake—please speak with your physician. Your physician will be able to evaluate any potential risks and provide individual guidance.

Sources:

Chatterton RT Jr., et al. Hormonal Responses to Psychological Stress in Men Preparing for Skydiving. The Journal of Clinical Endocrinology & Metabolism. 1997;82:2503-9.

Hackney, AC. Endocrine Stress Reactivity Associated With Extreme Sports. The University of North Carolina.

Sherk VD, et al. Hormone responses to a continuous bout of rock climbing in men. European Journal of Applied Physiology. 2011;111:687-693.

Stenner E, et al. Hormonal responses to a long duration exploration in a cave of 700 m depth. European Journal of Applied Physiology.  2007;100:71-8.

van Westerloo DJ, et al. Acute stress elicited by bungee jumping suppresses human innate immunity. Molecular Medicine. 2011;17:180-8.

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