In Tai Chi, the Kwa is the area of power and is roughly between the hips and below the navel. To do a Kwa stretch, the knees are slightly bent (not locked) and remain stationary. The feet are rooted to the ground. Put your hands at the crease of upper thigh and abdomen. Sit back and down, like you were going to sit on a bench behind you. Only go back and down an inch or so. Your hands should feel the crease deepen. Do this for 3 or 4 reps. once a day. The stretch will also massage the ascending/descending colon and will help relieve constipation.