You may not believe a 50 and 1500-meter distance race has the same pacing strategy, but remember all that matters is who puts their hand on the wall first.
One main reason going out slower and having a more “even” pace is better than flying and dying is due to the use of creatine phosphate (CP). Many are familiar with the supplement creatine, but certain research makes this compound more intriguing than once thought.
Energy contribution from the CP system is mainly thought to last for 6 – 10 seconds at the beginning of a race, then diminish. However, studies inducing severe fatigue note CP is still present in the body, therefore CP system never shuts down completely.
Dr. Maglischo brings to light the fast and slow acting role of CP. He notes CP isn't necessarily used rapidly, if the athlete does not go out too fast early in the race. This increases the amount of CP in the body and allows longer ATP production to hold off off fatigue. Now don't get me wrong, CP isn't the only source of fatigue, as Dr. Maglischo notes:
“research on reducing the rate of creatine phosphate use during exercise, increasing its rate of restoration after exercise, and the effects of supplementation of this substance on performance, should be accelerated. Research on ways that the rates of accumulation of inorganic phosphate and ADP can be reduced, or mediated, within working muscles during exercise should also become a priority. The possibility that training may also increase their rates of removal from working muscle fibers through either active or passive metabolic procedures is also a topic worthy of study. Likewise, new training techniques that may achieve these effects should also be explored … Finally, we should not dismiss the role of lactic acid in muscular fatigue as inconsequential. After all, at the present time, acidosis has not been absolutely discredited as a cause of muscular fatigue (Maglischo 2012)”.
As you see, pacing 101 for swimmers is becoming more common in elite swimmers. Finding a steady pace and maintaining this speed is critical for success, likely from the maintained use of the increasingly important CP.
CP isn't the only factor in fatigue, but as swimming is not against gravity, uses a cooling medium, and is rhythmic, CP can likely be used even longer than other sports. The next installment of pacing 101 for swimming discusses methods to delay the onset of fatigue.