HOUSTON (KTRK) --The Houston area is home to a lot of extreme competitions including marathons, obstacle courses and triathlons. To get into shape for these events, many people opt for trendy high intensity interval training -- or HIIT -- programs to reach their fitness goals. However, the "go hard or go home" style of this extreme exercise has developed a reputation for serious injury.
At the core of this extreme exercise are high impact moves completed over short periods of time (sometimes without breaks) that are designed to push devotees to the limit. Many do it for the adrenaline rush. Others do it because it pays off quickly.
"You can get in and get out in an hour, and you feel like you've just done a week's worth of work," said Andrew Wood, a coach and co-owner at Village CrossFit in the Greenway area of Houston.
One of the best known high intensity interval training programs is the ever-popular CrossFit strength and conditioning program. With more than 160 CrossFit "boxes" in the Houston area, coaches say the workout mimics everyday body movements.
"They're functional movements, like squatting," Wood said as he demonstrated motions that looked like someone standing up from a sitting position.
Yet, it is the high-speed, high-impact, "give it all you've got" style of this interval training that many doctors say lead to serious and sometime repeated injury.
"This is an explosive type of exercise workout that they're doing -- very high intensity, whether it be with weights or cardio," said Dr. John Higgins, a sports cardiologist with UTHealth and Harris Health System. "They're getting a lot epinephrine and adrenaline, and sometimes they may not feel that they're getting injured during the actual exercise event," Higgins said.
Shoulder, lower back and knee injuries are among the most common complaints from fans of HIIT and programs like CrossFit, though the number of injuries has been difficult to document. A 2013 report from the National Strength and Conditioning Association (NSCA) linked a significant number of overuse injuries to CrossFit in particular. When CrossFit disputed the study, the NSCA issued a correction, making hard data about the sport's injuries difficult to pinpoint.
One serious condition that has been associated with extreme exercise of all kinds is rhabdomyolysis. Known to CrossFitters as "Uncle Rhabdo," the condition is a breakdown of muscle tissue from overtraining. Muscle fibers end up in the blood stream, which can be damaging to the kidneys.
"It can be irreversible," said Dr. Higgins of the danger rhabdo poses. "In fact, there have been cases of young athletes who have developed rhabdo, gone into the hospital and ended up dying."
To prevent injuries, experts say what is most important is finding an experienced, certified coach to guide you through high intensity workouts. CrossFit uses an online portal to search for credentialed, CrossFit gyms.
If you are just beginning your foray into HIIT, coach Andrew Wood says to look for a gym with smaller class sizes. "We do that so the athlete to coach ratio is small enough so that I can actually watch everybody in class and make sure everybody's doing the movement efficiently, effectively and safely," Wood said.
It is also important to know your pain threshold. Doctors say there is a fine line between discomfort that is challenging and discomfort that is unhealthy.
"To quote Churchill, 'When you're going through hell, keep going,' and it's at those times, occasionally we over do it," said Dr. John Higgins with UTHealth and Harris Health System. "You will have to pay for it later because you'll have to take a little time out from exercise."
Among other tips offered by doctors and coaches, go low and slow if you're just getting into HIIT workouts. Allow your body to recover and always combine any extreme exercise with proper nutrition, hydration and sleep.
A CrossFit coach, Wood says there are ways to push your body to the extreme -- though in a safe way that avoids injury. "Just remember that you should have fun getting fit," Wood said.
A spokesman for CrossFit has said it is likely more doctors are seeing injured CrossFitters because so many people have joined CrossFit gyms over the past few years. The CrossFit brand has more than 13,000 locations around the world.