One time at running camp wrote:
I remember a coach speaking about energy usage during a race, and the bit that stood out to me about “getting out hard” was that the body uses the alactic energy system during the first 10 seconds of the race. It seemed to me that it was “free energy” that was going to be used whether you took advantage of it, or not.
This--except that for most people, the freebie is more like six seconds than ten.
I just tell my athletes to use their "free energy" to get up to their pace quickly, then settle in to it. This typically takes just a couple-few seconds. I never want them walking off the starting line, but if they prolong their opening spurt beyond those few seconds, they can pay a high price later in the race.