Marathon mystery: Did I really run 27 miles?

Boston Globe

18-04-2025

But when I crossed the finish line, I had missed the mark. Badly. Official time: 4:04:04. According to my Garmin running watch, I had logged 27.13 miles, nearly an extra mile. Before you think I'm some outlier, my buddy Mike Barowsky traveled 27.39 miles, according to his Strava app. How had our glory, that we alone cared about, been snatched from us?
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Our tale of woe is far from unique. I've heard the same saga from many runners, in marathons and shorter races alike: Your app or watch tells you one thing, reality tells you another. It's a gut punch. Whoever says just running 26.2 miles is accomplishment enough regardless of the time either has never run a marathon or is annoyingly well adjusted.
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The key to a marathon is pacing: You want to go out fast enough, but not too fast. My running watch should have been keeping me in check. But all it does is measure how long it takes you to run a given distance. If a marathon route is actually longer than 26.2 miles, hitting your targeted per-mile pace isn't going to lead to the finishing time you're aiming for. Or, if the watch
thinks
your miles are shorter or longer than they actually are, it's not going to display an accurate per-mile pace.
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That means there are three possible culprits for my mishap in Philadelphia.
Theory number one: My GPS watch failed me.
Theory number two: I ran a highly inefficient race, making lots of unnecessary zigzags.
Or number three: The guy who laid out the course had too much to drink that day and I really did run farther than 26.2.
Here's why I like the last, albeit self-serving, theory. Many runners alongside me were caught in a similar timer panic, selling me on the idea that the Philly fix was in.
Let's start there and work backward.
'Everything is subject to human error,' said Kathleen Titus, Philadelphia Marathon Weekend race director, when I asked her if a course mistake was possible.
That said, her route is laid out by a certified course measurer who rides a bike the length of the course 'frontwards twice and backwards twice,' Titus said. The measurer uses a Jones Counter, a special bicycle odometer. The bike's tire pressure is checked to ensure accuracy.
The course is
Pretty airtight.
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Well, of course Titus is going to defend
her
course!
I reached out to THE running guru for countless amateur runners, Hal Higdon, author of the book 'Marathon: The Ultimate Training Guide,' among other titles.
He said the people who mark marathons are 'total nerds who would be insulted if somebody told them they didn't measure the course right. They totally focus on getting the exact measurement, not 2 inches off.'
Higdon did say that on very rare occasions a police motorcycle leading the pack takes a wrong turn for a block or two.
Or sometimes, when a volunteer puts down the cones, they mess up, more likely at a smaller, local race.
When mishaps occur, however, social media is unforgiving. I couldn't find any complaints about my race, so as much as I want to, it's hard to blame Philly for my shortcoming.
OK, next theory: I was the problem.
Higdon, who has run 111 marathons, gave me a dose of tough love: 'You just need to look ahead.'
'Runners don't focus on what they're doing and have a tendency to wander,' said Higdon. Between bathroom breaks, high-fiving spectators, and getting water, 'We're sort of a group that's out of control.'
For those who can stay in control, Boston College men's track and field assistant coach
Then there are the turns that go right, then left. For those, you want to run 'the straightest line possible,' Titus said. 'Which is hard to do,' even for Titus, who has run more than 115 marathons.
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Philadelphia has lots of turns.
Add it all up, and of course I ran a bit long. Everybody does. But I probably didn't tack on nearly an entire extra mile, which leads me to ...
Theory number three: My watch deceived me.
When I look at the granular race data from my GPS mapping, it has me running through buildings, even doing a small 360-degree twirl. (I did not.)
'The GPS receiver in the runner's watch is not perfect,' said Joe Heikes, lead project manager with Garmin. 'There is always some noise in the position measurements.'
When running between tall buildings, I believe the nontechnical term is that your GPS measurements go 'absolutely kablooey.'
Heikes said tall buildings cause '
'Even in the best of conditions, there is always a little uncertainty,' said Heikes. 'The receiver in your watch looks at all those satellite signals and thinks you are standing on 'X,' but you might actually be 40 centimeters or 10 meters away from 'X.''
The author's GPS watch recorded his route in the Philadelphia marathon with loops and zags he didn't actually take.
Jason Margolis
Multiply all those miscalculated centimeters over 26.2 miles, and it's no wonder things don't quite add up. Bottom line: I should have paid more attention, and adjusted, when the readout on my watch made it seem as if the race course's mile markers weren't in the right spots.
In my defense, though, some of my fellow runners at the Philly Marathon were saying things were off, that the mile markers were approximations, and I figured they knew what they were talking about. And when I'm out on a suburban running path with mile markers, my watch is pretty close to perfect, so I put a lot of faith in it on race day.
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In Philly, Titus said, there's also a 'dead zone' for a half mile, so your watch has no idea what's going on there.
Then there's the fact that not all GPS devices are created equal. I have a midlevel watch, perfect for me, but lacking
In Philadelphia, my buddy Barowsky used the Strava app on his phone, so I reached out to the company about what might have caused his errors.
They directed me to a support article. It said, 'Things like GPS drift, GPS signal loss, or a 'jumpy' GPS track can also cause your activity to report more or less distance than you actually traveled.'
So, what's a runner to do on race day?
McGowan's advice: 'Don't let your watch take away from the amazingness of the event.'
Others advised me to ask myself: Why am I doing this? For recreational runners, does anybody truly care about your time except you? (No.)
Maybe if I can gear up for another 26.2 miler, I'll try a totally different approach: Ditch my watch, embrace zigzagging to high-five spectators, and just run for the sake of running. After all, as somebody once told me, the accomplishment of a marathon is just doing it.
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Jason Margolis can be reached at