Dr. Timothy Noakes, in his writings about the importance of the athletic brain, states that, «the ultimate control of exercise performance resides in the brain's ability to vary the work rate and metabolic demand by altering the number of skeletal muscle motor units recruited during exercise.» (philmaffetone.com)
This means you can train a bit harder, push out an extra rep (or slightly increase your max, since the additional short term energy will allow muscle motor units to contract for a bit longer, increasing the useful power peak), sprint a bit longer, recover just a bit faster... which is an advantage to nearly ALL athletes. (completehumanperformance.com)
Here's why overspeed training works: it is an effective way to recruit new muscle tissue, specifically by engaging more muscle motor units than by training at lower speeds. (bengreenfieldfitness.com)