The MO is actualy refering to the Medical Officer every recruit loves to visit once in awhile to avoid and run away from training. They'll issue Yellow arm bands to notify other higher ranking people that this recruit has a medical status.
No sergeants would forced you to do training nor punnishment :)
This 2 month of BMT(military training), i had fever once, cough almost everyday , fell and bleed once(today) and never once visited the MO. See how much perseverance i've got! :p