One cannot sustain the pace well nor finish fast without providing enough oxygen to the body.
Knowing how to pace a race appropriately is one of the most difficult aspects of competitive swimming. It goes against our very nature, particularly when we are excited and fresh at the start of each race, to hold back. Yet holding back, keeping our emotions under control, is precisely what we need to do in order to prevail.
To some degree, every officially sanctioned race in the sport of swimming requires pacing. Even the 50-meter swims, which are not true sprints, require self-control and discipline in order to be done well. Most of those 50’s are won or lost in the last 10 meters.