I've heard so many horror stories about yoga teachers and personal trainers (or not) taking their students or clients to unsafe territories in their bodies.
Working out isn't supposed to make you want to throw up, and yoga isn't supposed to hurt. Practicing it is supposed to make you feel better, but doing it wrong is just dangerous.
After being a personal trainer at Equinox in Santa Monica and working as a yoga teacher at several studios including a gym, I've seen it all. Students wobble into class injured, saying they can hardly walk due to an injury from their last class. I've had students not come to my class for months because of an injury they received after going to another yoga class that took them far beyond their capabilities. Obviously, this is all subjective and students/clients should monitor their own bodies. But seriously, some teachers are out of control. I've heard about a certain incredibly famous power yoga teacher actually popping a students rib out of place from pressing too hard on his back. Some teachers assist and have no proper training in how to do so. Not cool.
Weekend Warriors
Often times people get hurt because they assume that yoga is simple and that anybody can pretzel himself or herself on demand. Edward Toriello, an orthopedic surgeon and spokesman for the American Academy of Orthopedic Surgeons says, most of the injuries he sees are sustained by "weekend warrior" baby boomers who being yoga or work outs without realizing that their bodies are no longer what they used to be."They think yoga is an easy way to start exercises, so they go to class once a week, not stretched out at all and they get hurt."
Same goes for cardio and especially for weight lifting. I had many clients who insisted on benching more weight "because it's what they did in college" but what they don't realize, is that they aren't that person anymore. That's when they get injured and then have to lay off exercise for weeks to properly heal. Functional strength training is much more effective for optimal results.
Legit?
Part of the problem is that increasingly, the people teaching yoga don't know enough about it. Yoga was traditionally taught one-on-one, over many years. Today's instructors can take a yoga teacher training course in just one weekend. Luckily, to be in the Yoga Alliance (formed in 1999) has set a minimum of 200 hours for instructors to be certified. Unfortunately, only 16,168 of the over 70,000 yoga teachers are actually in the Yoga Alliance. This is a very pertinent issue, especially when it comes to injury.
Wherever you chose to practice or work out, studio, gym or with a personal trainer at the beach, just make sure you listen to your own body and take care of yourself. If you don't, nobody else can be expected to. Warm up before activity/exercise, then stretch when muscles are warm, and stretch for a longer amount of time after activities. For Weekend Warriors, if you can't get to the gym other than weekends, be sure to stretch during the week for 10-15 minutes... it will make a world of difference! And If something hurts... stop doing it!
After being a personal trainer at Equinox in Santa Monica and working as a yoga teacher at several studios including a gym, I've seen it all. Students wobble into class injured, saying they can hardly walk due to an injury from their last class. I've had students not come to my class for months because of an injury they received after going to another yoga class that took them far beyond their capabilities. Obviously, this is all subjective and students/clients should monitor their own bodies. But seriously, some teachers are out of control. I've heard about a certain incredibly famous power yoga teacher actually popping a students rib out of place from pressing too hard on his back. Some teachers assist and have no proper training in how to do so. Not cool.
Same goes for cardio and especially for weight lifting. I had many clients who insisted on benching more weight "because it's what they did in college" but what they don't realize, is that they aren't that person anymore. That's when they get injured and then have to lay off exercise for weeks to properly heal. 
Part of the problem is that increasingly, the people teaching yoga don't know enough about it. Yoga was traditionally taught one-on-one, over many years. Today's instructors can take a yoga teacher training course in just one weekend. Luckily, to be in the