Aloha Linda,
I'll see if Master Lin has a clearer explanation to contribute.
Physically, your bringing in the lower abdomen slightly and allowing the breath to fill from there all the way up the chest.Then on the exhale it releases all the way down until at last you release your lower abdomen.
Regarding small universe, it's not about straining to extend your inhales and exhales to the "omms" and "muahs". You may find your physical in/exhales finishing earlier than the sound. Even though the physical breath stops, the energetic breath continues as your still feeling and visualizing the energy flowing in or out of your body throughout his sound.
Much love, Shawn
[This message has been edited by Shawn_Grim (edited February 25, 2002).]