The iliopsoas muscle (or hip flexor) can be prone to shortening especially for office workers who spend a lot of time sitting where the muscle is in its shortened position.
This stretch when done correctly is good for preventing that pose where the back is arched and the butt is out.
The shortened psoas muscle can also cause lower back pain due to the fact that there is less hip joint movement and this slack is taken up in the lower lumbar region.
hip flexor stretch start position
Kneel with one kneee on the ground and the other knee out in front at a right angle to the floor.
The rear foot can be raised by resting it on a chair or something of the correct height behind.
Tuck your chin in.
Ensure that your pelvis remains square at all times, This will prevent the lower back twisting and reducing the stretch.
Take a deep breath in.
hip flexor stretch end position
While exhaling, slowly move your chest forward to the extent of the movement.
Inhale while slowly moving back to the starting position.
Repeat this 5 times for each leg.
The pelvis MUST remain square to isolate the correct muscles.