The Law of Compounding Miles

It is often said that the principle of compounding interest is the secret to accumulating a robust savings account. Because interest is added to not only the amount originally deposited but also to the interest already earned, the interest continues to compound. Over time the balance grows, often substantially. As I continue preparations for my third marathon, I believe the same law of compounding gains can be applied to marathon training.

Last fall’s New York City Marathon marked my first successful 26.2 training cycle. But while I was ecstatic to cross the finish line, I didn’t seem to notice any significant training gains. I wasn’t discouraged, after all I had reached my goal, but I didn’t really feel any more fit and my performance hadn’t meaningfully improved during the cycle. That seemed to change, however, once I began my second cycle ahead of April’s outing.

While I previously chronicled some of these gains, my procrastination in posting did not diminish the compounding results from training:

Screen Shot 2015-09-13 at 6.36.49 PMWhile excited to take on NYRR’s annual Brooklyn Half Marathon, I was a bit unsure how steady my legs would be since it fell just a few weeks after the New Jersey Marathon. Still a relative newbie, I wasn’t sure if I’d have enough recovery behind me to try for a personal best on the otherwise PR-friendly course. Alas, the laws of compounding miles kicked in and I was able to nudge my time down a notch to finish in 1:47:41.

For me, the one season that is least conducive to celebrating PRs is summer. So I knew that the early June Retro 4-Miler would likely be my last opportunity to continue my steady streak of lowering my pace per mile. So with temperatures hovering around 60 and only mild humidity, I set out to do just that. And by knocking my 4 miler time down by around 10 seconds, I was able to see my best pace per mile tick down to 7:47. With splits of 7:44, 7:34, 7:46 and 7:35, I was pretty pleased with the progress.

Screen Shot 2015-09-13 at 6.38.34 PMOf course, one doesn’t have to be a mathematician to wonder how, with splits like those — all less than my official pace per mile, would my pace not be lower, too? Simply put: tangents. Crowded races in Central Park (or anywhere, really) do not often lend themselves to running near perfect tangents. What can that mean when for a 4 mile race? In my case, running just an additional .07 miles in a 4 mile race is the difference between achieving an official 7:47 pace per mile and a 7:39 pace per mile. Not an insignificant differential! Official race results aside, the outing proved I was capable of running a 7:39 pace per mile, underscoring the compounding progress.

Screen Shot 2015-09-13 at 6.38.21 PMNow amidst my third training cycle in advance of the 2015 New York City Marathon, added gains have admittedly been a bit less tangible. The heat and humidity can be a volatile combination. Whereas last summer I was able to log most runs early in the morning, any attempt this summer to “beat the heat” has mostly been futile. Remarkably, despite Mother Nature, a cursory glance at my collective training runs for July and August suggest that my regular run paces have improved substantially – around 30 seconds a mile – over last year’s. Candidly, the numbers surprised me. I didn’t feel like they were any faster than last year’s, particularly given how prolonged my adaptation to summer running has seemed to be.

While I’m excited to see how my cumulative training will pay off on November 1, I can’t help but become animated thinking about how the law of compounding miles may impact my 2016 and beyond!


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