The harder you push, the better your workout, right? Not so fast. Although extreme exercise styles like CrossFit, Insanity and P90X are hot picks for gym-goers and home-exercisers alike, they may not be as safe as you think. As convincing as the commercials are (who isn't enticed at the thought of getting "ripped" at any age or fitness level?), they fail to show the potential dangers of extreme workouts. This doesn't mean you need to ditch these popular routines completely, but you should know the risks and learn to protect yourself before the intensive training begins.

The Potential Dangers

Perhaps the scariest risk of extreme exercise is that it occasionally causes a condition called rhabdomyolysis, called "rhabdo" for short. While rhabdo is rare, it can cause major health problems, and is sometimes fatal. Rhabdo occurs when muscle fibers break down and enter the bloodstream. These fibers, called myoglobin, circulate through the body and cause kidney damage.

Rhabdo may be caused by a number of factors, including injuries, statin drugs, amphetamines and severe exertion--just like the type that extreme workouts require.

ABC News recently interviewed a 29-year-old entrepreneur named Matt Lombardi who developed rhabdo after his very first P90X workout.

"I was so sore I couldn't lift my arms and then I noticed my pee was the color of cola," said Lombardi. "After Googling P90X and my symptoms, I immediately made an appointment with a kidney specialist."

Lombardi's experience landed him a five-day hospital stay. Fortunately, he was left without any permanent damage.

While not all of the risks of extreme exercise are quite so severe, doctors have been seeing more and more workout-related injuries since the upswing of these high-intensity routines. Dr. Stephen Fealy, an orthopedic surgeon, told ABC that he now sees at least one patient per week with sprained tendons or muscles from over-exertion.

The Benefits

Despite these risks, high-intensity exercise is not all bad. Multiple studies show that it burns calories more efficiently than moderate-intensity exercise, and even increases your metabolism for hours afterward. In a country plagued by obesity, any technique that helps people stay trim should not be discounted. After all, maintaining a healthy weight reduces the risk of heart disease, diabetes and other chronic illnesses.

The key is to know your fitness level and not push too hard. Over-exertion can send you to the doctor fast, so pause when you feel overwhelmed, and don't perform any activity that causes pain. If you've been a couch potato for the past decade, don't jump headlong into a new extreme workout routine--start slowly, and gradually move up to more difficult programs.

As with most things in life, moderation is pivotal for a healthy exercise routine. Allow ample rest between workouts--muscles need the recovery time to grow, anyway--and give yourself two days off per week to prevent overtraining. Approach your fitness routine with patience and common sense, and you can easily minimize the risks of extreme exercise.