Yes and No
Hi,
The contractions of abdominal (and even thoracic) muscles during apnea have been related with the urge to breath, and of course they are. But isn't only urge to breath they are related to "acid", "CO2" and mental status.
The blood acidity depends on many factors:Electrolytes concentration, buffers (albumin, phosphates, bicarbonate) concentration, and CO2 concentration. a profound acidity will stimulate your respiratory drive (urge to breath).
This contractions can be controlled, in fact, my brother(PB 8'12") dont have any contraction 'till 7'. And when is impossible to hold it, he concentrates to make is as smooth as possible that are unnoticeable.
My advice is that try to train holding the contractions,and when it comes make it very smooth (strong contractions consume a lot of oxygen)