Flat Back Posture is an overactive back chain and posterior tilt in your pelvic position. If you have Flat Back Posture, the quads (the front of your thighs) will be underactive. This is due to the overactivity of the hamstrings, gluts, calves, and the IT Band. It’s important with Flat Back Posture that you not only stretch out the overactive tight muscles in the back side of your body, but that you also strengthen the front body. The quads can be strengthened standing, seated, or lying down.
First: pelvic position
If you have Flat Back Posture, work with an anterior tilt in the pelvis (an arch in your low back). This will turn off those overactive gluts and hamstrings and allow you to turn on the quads and psoas.
Second: get to work
Select three different exercises for the quads. Spend one minute doing unilateral (single leg work) on your non-dominant leg, and then one minute using both legs for each exercise, if seated or lying. Repeat this unilateral and double leg quad work for 2 to 3 sets. A set is one minute or 8-12 slow reps.
Take your time.
Inhale to prepare, and exhale on the effort pulling your belly button in towards your spine and lifting in and up on your pelvic floor muscles (the muscles that stop your stream of pee) to contract your transverse abdominis (the deepest layer of your core) which protects your lower back.