MINNEAPOLIS -- For the past five years Deborah Cordner-Carson has been one of the most respected CrossFit athletes in the world.
She also coaches the workers at CrossFitMPLS and CrossFitSLP.
CrossFit is a branded high-intensity workout of stages ranging from tossing medicine balls while doing squats, to dead lifts, toe ups and many stages in between.
With that level of exercise injury can happen, but that's where a good coach comes in.
"It's the coaches responsibility to look at the athlete and say all right you can lift this weight, but you are doing it incorrectly and you are going to hurt yourself so I will scale you down," Cordner-Carson said.
With a workout as popular as CrossFit negativity was bound to come knocking.
It's come mostly online by bloggers and general skeptics who warn the workout has dangers its backer and coaches don't want to tell you about.
This past week a particular blog post went viral talking about what the author called CrossFit's dirty little secret.
The secret he was alleging was a rare disorder called Rhabdomyolysis.
"You can develop something called Rhabdomyolysis where the muscle gets so fatigued that those muscle fibers start to break down and then the proteins enter into the bloodstream and they can affect other organs in the body," Dr. Heather Bergeson with TRIA Orthopedics explained.
When that happens it puts pressure on the kidneys to work overtime and can be dangerous, even fatal.
But linking it only to CrossFit is unfair.
"It's rare and it's not just in CrossFit that it happens," Bergeson said.
She said it happens in high school weight rooms and on football teams as well as any other kind of high-repetition, high-strain workout.
It's an injury that comes when people push their bodies to the extreme.
For the past year, Megan Suszynski has adopted CrossFit as her workout of choice, so much so she was certified to coach it as well at The Firm in downtown Minneapolis.
"As a coach, it is our responsibility to give the individual in our class the knowledge and the knowledge we have about risks in workouts," Suszynski said of the Rhabdomyolysis danger.
So the best advice is simple, find a CrossFit coach who cares about how you do the reps, not just about how many reps you do.