Before you start:
This exercise almost entirely relies on core strength, most people will engage their rectus abdominis (the muscles that are visible in a six pack) but proper form will help also target the transverse abdominis (the deepest abdominal muscle). Through the progressions you’ll be able to see how elongating your body puts more stress on your abdominal muscles and makes the move more difficult, but shortening one aspect (bending the legs or bringing the arms forward, for example) will make it easier.
The first progression is essentially a boat pose from Yoga. Your knees are bent, your arms are reaching for your toes, and the only part of your body on the ground is your glutes. At this point you are simply adjusting to the feel of using your abs to maintain a position without relying on your feet or hands to rebalance. You can straighten your legs to further challenge this balance. When you can hold this pose for 30 seconds uninterrupted you’re ready to move on.
The next progression is very similar to boat pose, your arms are still reaching forward, your knees are still bent, except this time your lower back touches the ground. This introduces a couple new elements to be aware of with regards to form; the posterior pelvic tilt and engaging your transverse abdominis.
A posterior pelvic tilt occurs when you squeeze your glutes together and your hips thrust forward slightly (think of the top of a kettlebell swing). This position is important for the hollow body for two reasons; it straightens your lower spine (proper alignment for a handstand) and it will help keep your lower back on the ground. It’s absolutely key for the rest of the progressions that your entire lower back stays in contact with the ground, if your back arches and you lose that contact you need to move back to an easier progression.
Engaging your transverse abdominis in this position is important as the transverse abdominis muscle is the key to true core strength. Your rectus abdominis, the 6-pack ab muscles, may look pretty but they’re not quite as functional. In order to engage your TA you need to think about drawing in your belly button, so much so that you’re trying to get your belly button to touch your spine or the floor underneath you. You also need to activate your pelvic floor, which feels different to each gender. For more information about activating your pelvic floor and why the transverse abdominis is important follow this link.
Back to the progressions, the next step is to straighten your legs; you want to keep your legs “zipped” together, touching as much as possible, and point your toes. Your arms are still reaching forward, your lower back is still in contact with the ground, and you’re actively pulling your stomach down to engage your abs.
The true hollow body progression involves bringing your arms overhead, which will fully elongate your body and be the most challenging bodyweight move in this series. The closer your legs and arms are to the ground, the more difficult it is as well. In a true hollow body you should have a posterior pelvic tilt, your legs should be together, toes pointed, arms outstretched above your head, transverse abdominis and pelvic floor engaged, and lower back fully in contact with the ground. If you find your back begins to arch it can normally be fixed by either raising your legs up a few inches or moving back to progression #3.
Note: There is no “correct” position of your shoulders in a hollow body. This is because each position, protracted vs. retracted for example, is simple associated with a different gymnastics move. If you’re working on your handstand, protract your shoulders by trying to separate your scapula.
If you’re able to hold a true hollow body for 30 seconds uninterrupted you might need more of a challenge and you can incorporate weights to make this exercise more difficult. Simply strap some ankle weights on or grab a dumbbell or medicine ball to hold over your head, but never forget to constantly review your form.
If you have any questions about how to do these moves or need your form reviewed, please ask a trainer.