Summer Series Math

This post is purely of interest to those running the TRL Summer Series.

As promised, this year’s Shamrock Runs (and several other multi-race events in the TRL Summer Series) will be scored as a single race, with adjustments not only for the differing distances, but for the difficulties in the courses.

In the interests of transparency, here’s a quick peak under the hood of how I intend to do it.

First, I need a difficulty adjustment for each course, since some are flat, and others aren’t. To do that, I am calculating a difficulty factor based on parameters I have long used in coaching. These show that every 50 feet of climbing slows you down by about 15 sec, while each 50 feet of descent gives you back up to 10 sec, if you are a good downhill runner. That’s a net 5 seconds loss for each 50 feet up and down. If you’re not good on hills it might be 50 percent higher, but I have to pick a parameter, and focusing on good hill runners seemed best.

In my experience, these are good estimates for people running about 6 minutes a mile, so I scaled to that pace, calculating that running up and down 50 feet in a mile slows you by 1.39 percent. (That’s way too precise, of course. Think 1.4 percent, give or take maybe .2 percent.)

The slowdown is linear in over a wide range: i.e., 100 feet has twice the effect of 50 feet. This means I can use the total amount of climbing as reported on course maps to calculate an average amount per mile, kilometer, etc., for the entire course. That produces a handy handy spreadsheet I can easily adapt for other races–with the caveat that it doesn’t apply to net upgrades or downgrades.

Here’s the math, for Shamrock.

Race distance (m)Total climbing (m)Average upgradeParameterDifficulty factor
Parameter calculations
Slow down per 1% up per mile15 sec
Speed up per 1% down oer mile10 sec10 sec
Up and down average per mile5 sec
Percentage (based on 6:00 pace)

Once race times are adjusted for difficulty, I can then put them into age-graded tables, but instead of age grading them, can use open-class times. That gives a quick-and-easy way to compare, say, 68 minutes on the 15K to 21 minutes on the 5K.

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