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KANSAS CITY, Mo. — High Intensity Interval Training is the top fitness trend for 2014. Programs like Insanity, P-90 X, Crossfit and Orange Theory Fitness are so popular because studies show the programs feature the most efficient workout.

By alternating bursts of intense exercises with low intensity exercises, you burn more calories in a shorter amount of time, and your metabolism stays revved up after your workout concludes.

But as they gain popularity, more people are ending up with injuries and in rehab.

Kayce Hernandez is athletic and loves playing sports. She got the Insanity DVD to improve her fitness. But during a jump, everything went wrong.

“When I landed, it popped out-of-place. It was like a gunshot sound, it was so loud you heard it even way across the room,” she said. “I fell straight to the ground and I knew something was wrong and I couldn’t get up. I was screaming and the pain was unbearable.”

Hernandez tore cartilage in her knee. The injury happened six months ago and she is just now starting to slowly walk on a treadmill.

Her story is all too familiar to physical therapist Dan Lorenz. He says High Intensity Interval Training, or HIIT like Crossfit, is a boon for his business.

“Most people don’t have the mobility of their joints, the length of their muscles, the strength to tolerate the high intensity,” Lorenz said.

He ends up seeing a lot of people with knee, neck and lower back injuries because of these workouts.

Some gyms offer a ‘one-size fits all’ approach. However, Bootcamp Fitness/Cross Fit Kansas City has certain measures in place to help clients succeed at their own pace. Orange Theory Fitness monitors your heart rate throughout the workout to maintain the right heart rate zone.

For more on staying safe and injury free with HIIT, follow these links: