We all want to be in peak physical condition. It feels great, it looks great, and, luckily, going to the gym just two or three days a week will help us achieve the level of fitness to which most mortals aspire. But true Adrenalists need more. Much much more. To give you a sense of what it takes to ready your body for some of the most extreme activities on earth, here are five hardcore workouts sure to push any gym rat to their limit. Proceed with caution before undertaking any of these, because each could affect a drastic change in your physical appearance and a spike in your ability to complete near superhuman feats. Oh, and also soreness. Lots and lots of soreness.

CrossFit Paleo Challenge

Do you want to go from couch potato to muscle-bound machine in just 8 weeks? If yes, CrossFit’s “Paleo Challenge” workout is the answer to your prayers. The training regimen that’s turning hoards of motivated gym-goers into specimens worthy of a place in Sparta’s Army has two prongs: diet and fitness. For diet, CrossFit participants must subsist on a so-called “cave man” menu, eating only meat, fruits, nuts, and veggies. No sugars, grains, dairy, starches, or alcohol. That’s the easy part. The real work comes during hour-long sessions during which participants do everything from runs and chin-ups to hammer swings, handstand push ups, dead lifts and 400-lb. tractor tire flips.

Navy SEAL Fitness Test

The Navy SEAL Fitness Test ensures anyone who makes it into the SEAL prep program, known as Basic Underwater Demolition (BUD/S), will be able to survive the succeeding, notoriously rough boot camp experience. Just to be considered for membership in the SEALs, trainees must complete a 500-meter swim in under 12 minutes and 30 seconds, 42 push-ups in 2 minutes, 52 sit-ups in 2 minutes, a minimum of 8 pull-ups and a 1.5-mile run, in under 11 minutes and 30 seconds. No Nikes are allowed — just heavy boots and pants. Go ahead and try that workout at home.

MMA Workout

MMA fighter Jens “Lil Evil” Pulver walked Men’s Fitness through a pre-fight routine he says preps his mind as much as his body. Pulver begins workouts by running 5 minutes of 25-meter sprints. Next, he does 5 minutes of pushups, jumping jacks and bench dips, repeating the cycle until time is called. Then comes 5 minutes of lifting where Pulver alternates between slinging weights and tossing around a heavy bag. Plyometrics, intended to condition and hone speed, come next. The latter half of Pulver’s program is reminiscent of CrossFit, peppered with giant hammer swings, quad-burning squats and medicine ball touches. The first ever MMA lightweight champ finishes off with an entire circuit of grip work — intended to bolster his ability to grapple with opponents. Key elements of this final step include pull-ups with a tennis ball between his fingers and the bar, and pinching together 25-lb and 35-lb plates for as long as he can. Ouch.

Russian Crane Workout

Pushing yourself to the limit in an extreme workout is always a bit risky insofar as you might drop a weight on your foot or twist an ankle during a sprint, but these Russian daredevils give “no guts, no glory” a whole new meaning. Hundreds of feet above the ground, with no safety harnesses, this group uses the steel beams of a crane to perform chin-ups, hand stands, lunges and push-ups. Dangerous as it is, this crazy crane routine could be the ultimate calorie burner as participants probably sweat as much from being deathly afraid as they do from performing acrobatic maneuvers. We could be wrong, though. These guys don’t look too concerned about anything but getting ripped.

Fre Flo Do

Fre Flo Do is what it takes to become one of the most dominant forces in football, and Reggie Bush is living proof. Created by LA-based trainer Kappel LeRoy Clarke, Flo Do is born out of an Eastern philosophy called The Way, which is all about “Living life on the path from which freedom flows,” Clarke says. Sounds relaxing, huh? It’s not. Every exercise takes place on Clarke’s signature “launchpad,” which works like a treadmill, forcing athletes like Bush to stay in constant motion. With a client like Bush, Clarke’s objective is to hone agility within a constantly changing workout landscape. He’s been known to swing baseball bats (slowly, of course) at Bush’s legs and body to see how quickly he can avoid potential contact. Somersaulting over medicine balls while on the launchpad is also part of the norm in a segment called “Diving Ball”. Going up against 300-lb lineman must be a cake walk after this.

Cover Photo Credit: KetuGajjar / Flickr.com