Bend Your Knees

“Bend your knees.” I say this quite often in my yoga and other standing group fitness classes. In fact, I’ve worked with my current group of yoga students so much that I know I don’t need to say it as often, only emphasizing when I have a new student or see someone locking his or her knees. I’m confident that when they participate in another instructor’s class they won’t throw this rewiring, so to speak, out the door. But why do I say this? Because the number one issue people have with pain in their body is felt in the lower back, and one of the best ways to either prevent injury or ease pain in the low back is by simply bending the knees.

One of the most interesting concepts I remember from my personal trainer certification is the three classes of levers. Don’t worry, I’m not going to go in depth with all three. Just visualize a seesaw: there is a beam or rod, a fixed hinge (where the movement occurs), load or weight (kids on the seesaw), and the effort (whoever is pushing to go up). Now visualize the body as a whole as a lever. I say the body as a whole because there are multiple levers and hinges throughout the body, and we just want to focus on the spine and knees for now. When standing upright, the hips act as the hinge while bending over, the legs are the load because they bear body weight, and the upper body is the effort because of the spinal muscles contracting (effort) to make the body upright again. Depending on if we are bending over to pick up an object can greatly change the weight of the effort. There’s some math involved in this equation, but math makes blood pour out of my nose and ears, so we’ll skip that. When we bend over from the hips, we now have two levers: the lower body and the upper body. We were given knees for many reasons, but a significant, albeit not thought of reason, is to help counterbalance the load on the spinal disks and ligaments. When we bend our knees to bend over and stand back up, we are shortening the lower lever. This then reduces the load and effort being put on the spine because we are reducing the amount of weight being brought back to the upright position, by bending our knees.

Let’s take this a step further. We have a chain of connecting muscles that run along the back of our body: the calves, hamstrings, gluteals, and spinal muscles. Typically, our hamstrings and spinal muscles are tight; sitting for extended periods of time trains the hamstrings to be shortened, therefore, tight. Alternatively, our hamstrings may be overused if we have an anterior tilt of the pelvis; that is, our tailbone points behind us rather than toward the floor. This shortens our lower back muscles, making them tight, and actually lengthens the hamstrings, keeping them always “on,” so to speak. If we bend from our hips with our knees completely straight, we are then over stretching the hamstrings which will pull the already tight back muscles. Put the equation together of having either weak or tight muscles being overly stretched with the weight and effort of the lower lever system of the body, and you will likely run into an outcome of pain and/or injury.

I once trained a young client who had just finished physical therapy after having her lumbar (L4 and L5) disks operated on. I asked what she did to injure herself and she told me she picked up a heavy box from the floor. I asked her to show me how she lifts something up from the floor; she locked her knees and quickly bent straight down. Part of our training became focused on performing functional movements correctly, i.e., sitting down and standing up, bending over, reaching up to grab an object, lateral movements and twists. The other focus was on strengthening her core muscles. Both of these focuses served as injury prevention. But I also overemphasized the importance of bending the knees, even when standing in one place for a period of time. The basis for every class I teach and person I train is of injury prevention; after all, I work in the health and wellness industry. I once watched as one of my coworkers bent down with both knees locked and changed weights on a barbell. Yikes! I cringed. If the instructor is performing movements like this incorrectly, the class will do the same. So, take care of yourself, bend your knees.