Physical Therapist Aaron Swanson blames the epidemic injury rates from Crossfit on two things: constantly training to (and past) failure, and not training unilaterally enough. He addresses these points in a series of two posts (part 2 can be found here.)
At the same time, he makes a point that we ought not to forget:
As many physical therapists have probably noticed, there is an increase in the amount of Crossfit athletes showing up in our clinics. This isn’t because it injures everyone. It’s because it’s becoming very popular and people love it.
We see the same thing happen during ski season and marathon season. It’s not necessarily the activity, it’s the increase in participation.
So when you jump to the conclusion that “I heard Crossfit is dangerous and causes plenty of injuries,” also say to yourself, “but so does every other sport out there.”
Crossfit’s problem is that it encourages everyone to attempt olympic weightlifting at high-intensities from day one. Of course this is dangerous; olympic weightlifting is an olympic sport. We’d see just as many injuries if we put people into a pair of skis for the first time and told them to race to the bottom of a hill. With any other sport, we take the time to learn proper technique and ramp our way up to high-intensity. Only in Crossfit is intensity defaulted to maximal from the get-go.