Exercise Overload: Are We Pushing Ourselves Too Far?

Intense fitness program promise big results but is there danger if people overdo it?
3:00 | 01/16/14

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Transcript for Exercise Overload: Are We Pushing Ourselves Too Far?
Lots of us exercise to get healthy or to get slimmer, but what if we tell you tonight there can be dangerous side effects. In some extreme circumstances, exercising can be hazardous to your health. High intensity training is a top fitness trend, but there's a line, and many are crossing it. Here's abc's juju chang. Reporter: Katherine schreiber says she's addicted to something post people would praise her for. She's been known to hit the gym obsessi obsessively. This is my first love. Two hours before work, an hour at lunch, another session after work. I don't stop because you're not worth if you stop. You're worthless. Katherine is a self-proclaimed exercise addict, but rather than make her happy, she thinks it's a curse. You know, when people don't know your back story, they look at your physique and say oh, I'm so jealous of her physique? Absolutely. Reporter: What would you say? It looks better than it feels. I'm so envious. It's not something to be envied. The psychological turmoil that drives me to do this, it's not fun and I don't wish it upon anybody. Reporter: Our country is in the grips of an obesity epidemic, which may explain the exponential growth of hyper intensive workouts that promise to help you slim down and bulk up quickly. P90x, selling more than 4 MILLION DVDs. Insanity? More than 2 million. Crossfit, signing up 10 million cross fitters. Over the past five years, I've definitely seen an increase in the number of people going for an excessive type of a workout. There's sort of this escalating of competition between people to be more extreme and to be more hard core. Reporter: The desire for six-packed abs and chiselled biceps is driving people in droves to military boot camp training, hard core spinning, extreme endurance races. Even yoga, usually a refuge of peace and tranquility. Keep squeezing your thighs -- Jimmy: Now amped up to include those who love to be pushed to the edge. But extreme exercise has a dark side. Wh does it feel like when you don't work out? I get severely anxious. I get extremely irritable. I feel awful in my skin. I feel trapped in my skin. I'm rang pi. Angry. But it's counterintuitive. You exercise to get energy, but you exercise so much you lose energy? I'm completing myself. And I literally have not taken a day off in the gym in over two years. So no days off. Yeah. Even when I was sick. Reporter: Melissa elder is a trainer at equinox in manhattan. She says many clients are pushing themselves stronger than ever, and she thinks social media is to blame. You constantly have people showing images of themselves. People constantly see you and you want to impress, I guess. And you're judged by what you look like. People are more aware of how they look and more concerned with their workouts, I guess. Reporter: Wreaking havoc, not just on the mind but on the body. When you binge exercise, you're trying not to only negate every calorie you've taken in, but go beyond that so that you lose even more weight. Reporter: Katherine herniated a disc in her spine but ignored the pain. My understanding is that you didn't want to get it treated because you knew that it would take you out of working out. Yeah. Several doctors recommended that I get surgery and I flat-out said no because that would mean, I think it was two or three weeks off the gym. And that was inconceivable to me. I thought, well, I'll modify my workout. I pushed through the pain. We do have those bikes. What if you went to the gym at 6:00. No, I have to go to the gym now. First in the morning or whatever time. And she needs that structure within the workout. It's compulsive. Reporter: It's a familiar mantra. No pain, no gain. Although increasingly popular, doctors say these kinds of hard core intensity workouts can cause serious health problems, like rabdomyolosis, a rare condition that can lead to kidney failure. This is when the muscle tissue is so damaged from exercising excessively that it dies. It releases a chemical into the blood that can be very damaging to the kidneys. Which is what happened to jill. During my workout, I didn't have any warning signs. She wound up in the e.R. Days after doing intense crossfit exercise. Swelling from her elbows to her shoulders. In some instances, if this isn't taken care of, this could kill you. Reporter: In the past, crossfit says it doesn't teach trainers to push past their limits. Go, go, go, go, go! These are desperate cries from tough mudder runners at an event last spring. One competitor drown and hundreds stood helpless as a rescue diver prepped to go after him. Mask on, go down there! Reporter: The 10 to 12-mile race course includes crawling through mud, under barbed wire, running through four-foot high flames and sprinting through a field of live wires. The 28-year-old's death was ruled an accidental drowning. Shortly afterwards, they released a statement saying they take safety very seriously and test all obstacles prior to each event and have a fully trained medical staff on site. But just how tough is too tough? If you're missing out on work events or social events because you want to work out. Or if you're becoming anxious and depressed because you've missed a workout. Or you're not taking any rest days and you're you're working out if you're sick or injured, these go beyond just being fit and the realm of addiction. Tracy andersson, fitness guru to the stars says you have to know what you're doing. The truth is that it takes a lot of care and attention to achieve your best body. And it's possible, but it takes support. It takes education, and it takes people understanding that, you know, you are how you move and you do need to -- you do need to choose what you do carefully. I think the problem is somewhat cultural in the sense that we don't really encourage moderation in a lot of things. Especially with exercise. Reporter: Katherine has managed her obsessive exercising to under two hours a day on average, but she knows she has to be vigilant. Carving out time for friends and for her other passion -- writing. When I'm writing, I just -- I'm in the zone, really. It's the only thing that trumps exercise for me. Reporter: She says her various therapies are helping, but just today -- come on. Reporter: She took delivery of something she hopes will help keep her from obsessing about going to the gym, an elliptical machine. But perhaps she's just bringing her asixths home. -- Addictions home. I'm so excited about this right now. Someone with a problem with

This transcript has been automatically generated and may not be 100% accurate.

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