Some Americans are suffering from a debilitating condition which is brought on by how they worked out.
Casey Daniel, 30, has been learning to walk again after suffering from a rare condition caused by high-intensity workouts.
A physical therapist comes to Daniel's home three times a week to help strengthen her legs because she is battling Rhabdomyolysis, a rare condition that destroys her muscle fibers.
Along with the pain, one telltale sign of the condition, beside muscle pain, is extremely dark, almost black urine. Anyone exhibiting these symptoms should seek medical treatment immediately.
The condition is brought on by overexertion. Daniel says she got it after taking her first SoulCycle class in Los Angeles.
“The second day after the class I woke up and felt like I had been hit by a bus. I had some unusual bruising that was starting to happen above my knees,” she told Inside Edition.
Daniel, a Tennessee native who currently lives in LA, headed for the emergency room where she was rushed into surgery.
“I only had 10 minutes to call my family, who is all the way across the country, and tell them I was going into surgery,” she emotionally recalled. “I can't express how terrifying it is to not be able to walk and to be in that much pain.”
She had three surgeries to repair the muscles in her thighs.
Christopher Michael Everett was diagnosed with the same condition after his first spin class.
“This was just a whole different level of my legs swelling, painful to the touch, I can't bend my knees, I’m having fever, nausea, along with it,” he told Inside Edition.
He added that the pain was so bad that the 33-year-old Los Angeles-based actor had trouble sleeping and moving his legs.
Both Everett and Daniel say they overdid it in spin class.
There is a right way and wrong way to participate in the popular exercise, says Amanda Margusity, master instructor at Crank Cycling Studio in New York City.
Crank NYC, which has locations on the Upper East Side and in Long Island City, was founded by Anthony Maniscalco, who has been a fixture in the fitness world for more than 30 years.
“First thing when you walk into the room, make sure you tell the instructor it's your first time. They are there to help you set up, because set up is very important,” Margusity told Inside Edition.
She added that the saddle of the bike should be at hip height.
“When you hop onto the saddle, you want to make sure you are not hyperextending your leg to where your knee is locking out. And you also aren't too low where your hips are in danger,” she said.
During your workout, Margusity says you must listen to your body.
“If you feel like you are in the danger zone, where you are seeing spots and you can't control your breath in the moment, please get your instructor's attention," she said. "They're there to help you. They're not your enemy. They're your friend."
Everett and Daniel don't blame the cycling studios where their injuries occurred, but will look for alternative ways to stay in shape in the future.
“I will never get on a bicycle again, period," Daniel said. "This is it for me."