Formula for a New PR

newPR = raceDistance x (PR_pace_seconds – paceReduction_Seconds)

Here is the proof:

curPR = 1:27:30
curPR = (87 * 60) + 30
curPR_in_seconds= 5250
raceDistance = 13.125
paceReduction_Seconds = 5
PR_pace_seconds = PR_in_seconds / raceDistance
newPR = raceDistance x (PR_pace_seconds – paceReduction_Seconds)
newPR = raceDistance x ((PR_in_seconds / raceDistance) – paceReduction_Seconds)
newPR = 13.125 x (400 – 5)
newPR = 13.125 x (395)
newPR = 5184.375
newPR = 5184.375 / 60
newPR = 1:26:24

So that was the plan for Sunday's First Light Half Marathon.  Actually that has been the plan for all of my races.  However, I have found a flaw in the equation.  There is another variable which I will call raceConditions.  This variable will be measured in seconds per mile and will consider the external (wind, rain, heat) as well as the internal (fatigue, taper, illness, injury) conditions specific to the race.  In the past I have not had to adjust for conditions. I simply selected my races wisely and then counted on my increased running fitness to pull me through. 


For example if the race is windy I might need to give raceConditions a value of 3.  The new formula:

newPR = raceDistance x (PR_pace_seconds – paceReduction_Seconds + raceConditions)

Maybe the proof should have looked like this:

newPR = 13.125 x (400 - 5 + 3)
newPR = 13.125 x (398)
newPR = 5223.75
newPR = 5223.75 / 60
newPR = 1:27: 03