CrossFit can be a great workout, but you need to know how to pace yourself and give yourself plenty of recovery time. Image Credit: DjordjeDjurdjevic/iStock/GettyImages

Ryan Palmer had a tough week. On Monday, he battled squat presses and ring dips. Tuesday, a clean-and-jerk set where he squeezed out 30 reps with a 135-pound barbell. The following day, even though his muscles were still aching, he performed a total of 150 pull-ups and 150 burpees.

Palmer took a break from exercise on Thursday, but the next morning, he went for a long bike ride. The following day, his arms were uncharacteristically sore and swollen, and his urine was the color of black tea that had been steeping for hours.

Then, on Sunday, instead of hitting the gym, he found himself in a hospital hooked up to an IV drip that flushed his kidneys with more than nine liters of saline. As his creatine kinase levels — the amount of muscle protein broken down and in the blood stream — declined at a snail's pace, he posted a photo of the frightening results of a kidney test with the caption: "Uncle Rhabdo, is that you?"

Stories like this used to be common when CrossFit first exploded in popularity. Though the community as a whole has since pumped the breaks on the "no pain, no gain" mentality, many athletes still put themselves at risk of overtraining in their quest to be the best.

The State of CrossFit

CrossFit is a workout methodology created by former gymnast Greg Glassman in 2001 that's been steadily growing for a decade. According to CrossFit headquarters, there are now more than 15,000 CrossFit affiliates worldwide.

Each workout consists of a slew of exercise variety: Olympic-like lifts, cardio training and multi-joint movements like box jumps, pull-ups and burpees. Combined, these elements aim to "forge a broad, general and inclusive fitness," according to the brand's guidebook.

But the defining characteristic of CrossFit is the intensity. The programs are hard. Its "prescription," as the guide states, is for "constantly varied, high-intensity, functional movements that will optimize physical competence in 10 physical domains: cardiovascular and respiratory endurance, stamina, strength, flexibility, power, speed, coordination, agility, balance and accuracy."

The key to the high-voltage workouts is a digital clock that holds prime real estate in most CrossFit boxes (aka gyms). Most of the workouts are time-based, meaning you don't stop until the clock hits zero. Even as your muscles tire and you want to give up, coaches and fellow gym goers push each member to completion.

"As an adult competitive athlete, there's nothing else like this. You get that adrenaline rush that you got from being in sports in high school," says Jennifer Wielgus, a Philadelphia-based CrossFit athlete.

That rush and love of the gym is far from a bad thing, but the no-quit atmosphere of some affiliates has generated questions. Because even the healthiest of behaviors can be turned it into a dangerous obsession.

The Dangers of Overtraining

As Palmer's story above illustrates, Uncle Rhabdo was a frequent fixture in the CrossFit ethos. The cartoon character get its name from rhabdomyolysis, a kidney condition most commonly induced by excessive exercise, says Heather Gillespie, a sports medicine physician from UCLA.

The potentially life-threatening state, which can also be caused by genetics, occurs when muscle breaks down and myoglobin, a byproduct produced by muscle fibers, is released into the blood stream, essentially clogging up the kidneys and poisoning them.

"If you're dehydrated, which sort of goes along with rhabdo, you can't clear these toxins, the kidney can't filter the byproduct," Gillespie says. It can lead to kidney failure and electrolyte imbalances that can ultimately affect your heart.

Uncle Rhabdo was originally invented to shed light on "the inappropriate use of intensity," according to CrossFit's Training Guide. But some CrossFit athletes use it as a humorous way to prove that they've worked hard. Problems arise when CrossFit athletes and their trainers simply don't know when — or choose not — to call it quits.

"CrossFitters put up with burning muscles and overall strain so they're used to 'bring it on, gimme more, gimme more.' It gets hard to say oh, that's pain, I need to stop," says David Geier, Jr., an orthopedic surgeon and the director of sports medicine at the Medical University of South Carolina. "I think the benefits of CrossFit outweigh the risks — but the risks are real."

While many forms of exercise can result in overuse injuries, Geier sees them most frequently with CrossFitters because of the high-speed, high-impact approach. Certain exercises (Olympic lifts, specifically) are meant to be done in moderation, but CrossFit preaches pushing to the edge of every set, every rep, until there's nothing left in the tank.

And while training to failure is notoriously debatable, one thing is certain: Regularly pushing your body to failure can lead to serious health risks, like rhabdomyolysis.

"I have always taken the stance that training to failure causes useless fatigue," says Mark Peterson, an exercise physiologist from the University of Michigan's department of physical medicine. "Whereas fatigue is a normal side effect of certain types of metabolic training, I do not believe it has a time or place in training for strength and power."

The real danger is to new athletes. While the workouts can be scaled for all fitness levels, beginners usually don't know when "too much is too much" and don't understand the unique demand of an exercise session, says Eric Cressey, CSCS, owner of Cressey Performance.

Since many explosive movements require technical skill, Cressey says it's not advisable for Olympic lifts be completed in a fatigued state. Workouts that rely on training to excessive exhaustion and failure create an artificial perception of effectiveness. "These people might be doing a crazy workout and feel great because their endorphins are flowing, but then they wake up with their shoulder pounding with pain," he says.

His biggest concern is the technique that goes along with the workout. "When you see a 20-minute circuit of really ugly cleans and ring dips, those are exercises that don't jive well," he says.

The Problem of Ill-Prepared CrossFit Coaches

It bears mentioning: When done correctly, CrossFit is not inherently bad or ineffective. Like other training methodologies, CrossFit is a form of high-intensity exercise, an efficient model of exercise that has helped many people lose weight while improving strength and endurance.

But due to its popularity, too many CrossFit gyms have diluted the system. Just as some first-time CrossFit athletes overexert themselves to finish an overly ambitious workout, CrossFit coaches are rushing into setting up CrossFit affiliates and, thus, failing their athletes.

The problems stem from inexperienced trainers. CrossFit level-1 coaches are certified after completing a two-day seminar and 50-multiple-choice-question exam. That's all you need to open up a CrossFit gym and start training as many athletes as you want.

Zach Even-Esh, a CrossFit trainer at New Jersey's Underground Strength Coach, says the trainers at level-1 are just scratching the tip of the iceberg. "They tell you at level-1 that this is an introduction to understanding the basis of what CrossFit is about and that you need to take it to the next level," he says. But the reality is, someone with two days of education could be leading your next CrossFit class.

That's not to say there aren't well-experienced trainers coaching CrossFit across the country, but with a certification so simple to attain, the program produces a fair number of inexperienced trainers who end up hurting people. Cressey suggests those who want to be trainers wait one year before getting a certification. "If you have it without any experience, it makes you a liability, not a professional."

Further, after receiving their level-1 certification and paying a monthly fee, there are never calls from headquarters pushing for further education or refresher courses. "It does hurt the community because some people don't go out and educate themselves," Even-Esh says.

However, there's no lack of furthering education in the CrossFit community. The program offers level-2 training and specialty seminars in areas like kettelbell, mobility, power lifting, running and more. Even-Esh says he thinks CrossFit headquarters should require coaches to get a specialty certification every once in a while to keep their affiliation.