Treadmill Delusions

Don’t trust your treadmill, it could be misleading you.

Norman Marcotte
Runner's Life
Published in
4 min readFeb 5, 2021

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Photo by Kseniia Lopyreva from Pexels

In winter, when the snow, cold or icy roads prevent me from running outside, I fill up a water bottle and head down to the basement to run on the treadmill. I select either Netflix or YouTube and choose a video that will keep me distracted. I press the start button and jump on as I slowly increase the speed.

My preferred running distance is 10K. The duration allows me the opportunity to enjoy an episode or half of a movie, yet it is not so long as to feel tedious going nowhere. I follow the display to monitor the distance covered. For the training time, I prefer to use the GPS watch my spouse gave me on our anniversary last year. At the end of my session, I stop my watch to capture the day’s accomplishment. Later, the data uploads automatically on the Garmin online platform.

A few months ago while running in the basement, I noticed that the time on my watch was about 14 seconds slower than the treadmill time. That was a pleasant surprise, as it meant I was faster than it led me to believe. As I trusted my watch to be of higher accuracy, I did not ponder the variance any further.

Recently, I acted as the timekeeper for my spouse who was completing a 5K time trial on the treadmill. As I shouted the minutes and seconds for her first kilometer, we both realized it was about six seconds slower than the pace indicated on the display. With a panicked look on her face, she reached for the UP arrow and pressed it three times to increase the speed. The variance continued for every other kilometer. Fortunately, my wife responded to the numbers I presented and sped up to ultimately reach her goal.

Reflecting on the noticeable discrepancies, it perplexed me. For two different indicators, I obtained opposite trends. In one case, when I compared times, I was faster in reality. In the other case, when I compared paces, I was slower in reality. Being an engineer by trade, I wondered what technological limitations could create what I was observing. For a few days, I searched the internet but to no avail; I found nothing related to the differences I was encountering. Moreover, I racked my brain to make sense of the fact that the pace was erroneous in the opposite direction of the timing inaccuracy; after all, we…

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Norman Marcotte
Runner's Life

Writer, runner, mentor, dreamer. Author of "Take 10 and Reach the Boston Marathon" and the children's book "Frankenstein's Science Project".