Record your own yoga class, for personal reference.
(The Waist Rotating Pose)
Stand with feet shoulder distance level and arms outstretched in front of the chest and palms facing each other.
Healthy norm is to hold some tension in the hips and thighs when you twist. Hold the knees extended. Exhale, swing towards the left as far as possible and hold the position for some time with normal breathing. Make sure that the body from the tip of the toes till the pelvis remains stiff and does not move from its place. The arm on which side the body is swinging should be kept straight while the other arm should be bent. Gaze at the outstretched left thumb.
Inhale; come back to the normal position.
Exhale; repeat the practice from the right side as well for the same length of time.