The stack position is the optimal position for exercise. It is the most efficient position to use as a base to stabilize the torso and generate force. It utilizes the body’s deeper structures to create a foundation for the bigger muscle groups to operate.
What does it look like? The diaphragm under the rib cage and the pelvic floor at the bottom of the abdomen are the upper and lower boundaries of the abdominal area. They are two horizontally oriented structures in the body ideally, which would make them oriented directed over one another. The torso will have a vertical “stacked” position when that happens, and the core muscles can better operate from that position.
Most people have deviations from the stack position when they exercise. The most common is anterior orientation, which presents as forward pelvic tilt and/or upward flare of the ribcage. Performing exercise from this position is possible but is not as efficient and can put the person at a higher risk of injury. It also will limit how much range for movement the person will have for that exercise and for lifting specifically the person won’t be able to handle as much load.
How do I know I am in the stack position? The stack position is achieved from above using an exhale and from below using a hamstring tuck. It looks different than dumping that pelvis back or squeezing the shoulder blades together. It is achieved in more subtle changes in posture, but you can still see it happening.
In order to orient the diaphragm (rib cage) from above, you exhale allowing the ribcage to come down.
In order to orient the pelvis from below, the top of the hamstrings are utilized. The hamstrings are a muscle group on the back of the legs that originate at the bottom of your “sit bones” in the back of the hip and go down the back of the thigh to the knee. It’s this attachment on the back of the hip that we can utilize to exert a pull on the pelvis and bring it back into the correct position. The easiest way to think about it in standing is thinking about pulling your back pockets straight down. That is a hamstring tuck, and over time you should be able to feel that same tuck working as you are setting up to complete any exercise.
If it is too difficult to initiate either one of these or both in standing right away, you can use a 90/90 position to try to get the stack. A 90/90 position means having a 90 degree angle at the hips and knees, and the feet pressed on a wall. You can put a pillow or a small foam roll between the knees. You want to feel full contact from the heel, inside of the foot and outside of the foot on the wall. From that position, you can get the hamstrings going by trying to peel the feet down the wall and feeling like the knees are lifting upwards slightly. The hips will also start to peel up, and you should feel the top of the hamstrings working at that point. From that point, you should maintain the sensation of your hamstrings working as you complete the breathing part. The abdominals should be soft and not be contributing to the hamstring tuck. From that orientation, breathe in softly through the nose, and full exhale through the mouth. This exhale ideally will last about 8-10 seconds, but you may need to work up to that. The ribcage should be dropping towards the floor. Towards the end of your exhale, you should feel some tension in the abdominals building. Once you hit the point of abdominal tension, try to keep your ribcage in that position and pause for a second. After the pause keep the ribcage in the exhaled position and inhale softly through the nose again. At this point, you should feel the whole torso expanding. The idea is to create 360 degree expansion together. Once you feel like you have that cycle down, complete 5-8 breaths. Practicing this exercise should help feel the mechanics of creating a stack in a position that is easier to get it.
The stack should be applied to any exercise regardless of position. The more you check you boxes before an exercise, the more natural the positioning will become. This will allow you to not only give you the safest posture to lift from, but utilizing your body in the most efficient way will allow you to achieve maximum gainz!