The pace you need, lap by lap
Sub-5 comes down to four laps at roughly 74 to 76 seconds each, which totals just under five minutes if you hold it. Going out in 70 feels great for about 600 meters and then collapses badly, since the aerobic cost of that extra speed compounds fast over a mile. Even pacing beats a fast start almost every time at this distance. Most successful attempts run close to even splits, maybe a touch faster on the last lap once the finish line is actually in sight and adrenaline helps.

