One of my pet peeves, as a trainer, is the total disregard for proper exercise technique and inappropriate exercises selection. This is why people pay me big bucks (a relative term). And, this is what they would expect out their trainer. It is understandable if a gym member doesn't have good technique or that they are doing an inappropriate exercise, but a trained professional should know better.....right?
Last week I watched in horror as a gym "trainer" was having a brand new client, a women in her late 50's, perform a set of split squat jumps (starting in a lunge position and jumping up and landing back in a lunge position with the feet in the opposite position). Later, I found out he was 21 years old and really didn't have any experience training anyone besides himself.
Then, the other night I turned on the Biggest Loser while I was painting. We all know that the contestants on this show are severely obese and in poor physical condition. With that known, the trainers still make these clients run, jump, box, and attempt to do some strength training exercises, all with less than desirable technique to rapidly drop body weight. Jillian Michaels was training a female client, who had herniated/ruptured three lumbar disc several years ago, which didn't allow her to be active (she was a former athlete). Jillian felt that this girl was not working out with enough intensity and this contestant apprehension was due to her concern for her back (which is very understandable). So, Jillian had her perform a gymnastics's back bend (cringe) to show her that her back was healthy enough to workout harder!
I work with a lot of clients with a history of low back injury and pain. I can induce back pain with something as simple as a push-up (but don't). A back bend is one of the most stressful exercises you can do for your lumbar spine. The pressure on the lumbar discs (in the position this girl is in) is off the charts. A loaded ,extreme-bending of the lumbar spine should be avoided (to the untrained eye, you may not notice from this picture, but the majority of the spinal extension in is the lumbar spine. This girl does not have much flexibility in her hips to hyper-extend them. Also, she doesn't have much flexibility in her thoracic spine to extend there and lessen the hyper-extension of the lumbar spine).
One of the foremost researchers in spine biomechanics, Stuart McGill, has written several books on this topic. I am guessing Jillian has never read any of them. If she did, she would have learned that maintaining a neutral spine is critical. He recommends, starting with easy, basic spine stabilizing exercises. Then progressing to more challenging exercises, but still maintaining a neutral spine. Additionally, hip tightness needs to be addressed to allow you to maintain an neutral spine.
There are many better exercises to strengthen and improve stability of the lower back. Back bends are not one of them. Exercises like Bird Dogs, Planks, and Farmer's Walk are a good place to start. From there, more challenging exercises can be pursued, but not at the expense of spine stability.