My point is that focus on breathing patterns during a sprint race will take emphasis away from the cues you should be emphasizing.
IF one believes in a race model (I happen to) then following that model, Seagrave/McFarlane, the breathing pattern is sort of “dictated” by when/what of the model so it may help the cues.
As previously stated most info is anecdotal at best, on the other hand, related a bit to this discussion (what happens when the gun fires), where are you looking? Since some small amount of research indicates if you are looking at your feet at push off from the blocks the reaction is quicker…the theory being if you “see” it your brain, and from that body, reacts a touch quicker.