Could CrossFit be linked to deadly disease?

HOUSTON – Walk into any CrossFit gym and you'll notice that it looks nothing like your conventional workout facility. There are no treadmills or weight machines, but instead, you will find kettle balls, pull up bars, climbing ropes and gymnastics rings.

But, don't let its simplicity fool you. CrossFit is intense. Many people say they get results in just a few weeks. But, the intensity or obsession, as some would argue, can have a downside.

"There has been a lot of reports of rhabdo with CrossFit," said Dr. Vijay Jotwani with Houston Methodist Orthopedics & Sports Medicine.

Dr. Jotwani is referring to social media buzz about rhabdomyolysis ,or rhabdo for short. It happens when muscles are damaged from excessive exercise. The muscle breaks down and spills protein into the blood and certain proteins can be toxic to the kidneys.

So how serious is this?

"Rhabdo can be deadly," said Dr. Jotwani. "When you have kidney failure like this and you don't recognize it, you may need dialysis. It can lead to kidney shutdown. It can raise the potassium levels in the blood which can cause heart problems."

Before you cancel your CrossFit membership, Dr. Jotwani says rhabdo isn't just a CrossFit issue. He has seen it with football players and military recruits.

Other doctors we asked say they have diagnosed rhabdo in marathon runners and soccer players.