Every great feat taken on by an Adrenalist is inspired by the simple question, “how far can I push the envelope?”

No matter the sport, the season, or the prize, those who abide by an extreme lifestyle must feel that their physical actions are breaking new ground in order to be motivated. They must be convinced that if they accomplish what they set out to, their legacy will be solidified and inimitable (at least in the near future). Adrenalists don’t test limits for the accolades or because they think tricks are cool. They do what they do, risking their lives in the process, for a higher cause; to add to the pantheon of  human achievement.

Seeing as how Adrenalists are perpetually exploring and pushing their bodies to the breaking point, we thought it’d be useful to lay out some of our physical limits, the bounds beyond which even the most fearless athlete dare not venture. As difficult as it may be for a daredevil population to hear, there are rules for what our bodies can and cannot handle. Here are the limits of the human body.

Photo Credit: Gustavo Devito – flickr.com

How Fast Can We Accelerate?

Ever been zipping down a highway on your motorcycle and wondered how fast the human body can travel without bursting into nothingness? The answer may surprise you. According to an article published in the Huffington Post on human body limits, NASA and military researchers have determined that a person who’s undergone astronaut-level conditioning can withstand 14 gs of lateral acceleration (side to side jostling) before their heart literally bursts out of their chest. In terms of head to foot motion, or take-off motion, somewhere between 4 and 8 gs will render them unconscious. Interestingly, forward or backward acceleration seems to be the acceleration force that the conditioned human body is most able to withstand. HuffPo reports a human ability to hold it together at rates of up to 45 gs. Anywhere over that, and we’re kaput. Bottom line: unless you just bought a rocket, you should, physiologically speaking, be good to go as fast as you please. Just remember to heed speed limits and wear a helmet when necessary.

Photo Credit: Metsuke iLife – flickr.com

How Long Can We Stay Awake?

The answer to this question depends much more on how we define “awake” than on the sheer amount of time a human can remain alive while continuing to blink their eyes. Scientific American reports that, in 1965, 17-year-old high school student Randy Gardner stayed up for 11 days in an attempt to set a world record at his science fair. Other individuals have reported going without sleep for anywhere from 4 to 10 days without sustaining serious physical damage. Altered states of consciousness, however, became universally prevalent in those cases, which leads us to believe that during extreme sports where lack of focus could lead to life-threatening mistakes, it would behoove Adrenalists not to push much past a 16-hour day. Of course, if you find yourself stranded with resources dwindling and you need to spend every moment awake and searching for a way out, you’ll be able to stay up for quite some time. Just don’t pull all-nighters when you need to concentrate and physically perform.

Photo Credit: avlxyz – flickr.com

How Long Can We Go Without Food and Water?

Hunger can be debilitating, which is why it’s tough to believe a human body with ample extra fat can survive without food for up to 25 weeks, as reported by Professor House. It’s true that thinner people may only be able to get away with a fraction of that time and that your capacity to go without is directly related to how much spare meat you’ve got on your bones, but one thing is for absolute certain. No one, regardless of how much they weigh, can survive more than 3-5 days without water. Without food, your metabolism slows and your stomach shrinks as a survival instinct. You hold on to the nutrients you have for longer and you become less hungry so you can push on. Without water, you’re in real trouble and the cold, hard truth of it is, you won’t be able to get too far before your organs cease to function.

How Long Can We Survive in Extreme Cold?

Surviving in extreme cold has less to do with the temperature outside than it does with the temperature inside your body. Normal body temperature is 98.6 degrees Fahrenheit. Live Science reports that mild hypothermia sets in at 95 degrees, amnesia at 91 and loss of consciousness at 82. Anything below 70 and you’re at death’s door. There’s one recorded instance of an adult surviving a body temperature of 56.7 degrees, but that is not a limit you want to push.

Photo Credit: brandonprinceabroad – flickr.com

How Long Can We Survive in Extreme Heat?

Like extreme cold, extreme heat has everything to do with an individual’s body temperature. According to e-cloudy.com, the highest temperature at which the human body can sustain life is 108 degrees Fahrenheit. No one will stay around for long at that level, however, because essential bodily proteins begin to die off at 105 degrees. As far as external temperatures, even heavily guarded fireman can only withstand levels of about 200 degrees Fahrenheit. Where does that leave the rest of us? We are in danger if set in temperatures over 104 degrees. Depending on water supply and access to shade, that number can fluctuate pretty drastically in either direction, so beware.

Cover Photo Credit: Kaibab National Forest – flickr.com