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GPS Watches: Friend or Foe?

Has this happened to you? It's a gorgeous weekend morning, the sun is rising, a light breeze is fluttering through the trees leaves beside the path, your playlist has shuffled 3 of the best songs in a row, and suddenly …


You glance down and see you've drifted 1 second off the pace you wanted. No worries, a quick up tempo push, and …

BOO-BEEEEP "Too Fast" Ugh…

You quickly back off to another chirp, then push a bit more, your heart rate rises, and suddenly the run feels like work.

Allow me to start by saying I love my GPS watch. And these days, you're definitely in the minority if you don't run with even a simple tracking device as device sales and usage growth skyrocket. They provide so much data that it almost becomes overwhelming to analyze everything, but incredibly useful to the individual recreational user. However, these devices can also impact your day-to-day runs with problems that we tend to overlook.

First, there are basic device errors. Essentially, a GPS tracker plays 'connect the dots' with its tracked positions over time . Unfortunately, due to a range of limitations, such as line of sight and angle to the system satellites, these dots can get pretty out of position. Your data can become frenetic since the device is basing your speed/pace off these dot positions. Manufacturers have tried various algorithms to fix these outlier positions with varying degrees of success, but that leads to other issues in the smoothing. This is precisely why participants in races can run vastly different distances on the same measured course, especially in large cities.

I apparently swam a portion of Chicago marathon

Second, by its nature, the information you are basing your adjustments on is already in the past. A pace adjustment you undertake may be already corrected simply by passing over a small rolling hill causing an overcorrection. This, coupled with the inherent device data, especially adding in vertical error, means the user is constantly adjusting.

Third, most devices don't adjust your pace for incline, and even fewer compensate for the weather. Some devices are beginning to give some active pace management (Garmin's Pace Pro, for example), but this only works on preset routes with pace planning user preset. Unless you've spent the time to pre-calculate all the minutiae of an upcoming run, the device is going to loudly complain when you slow going up a hill. Add in a wind and temperature component, and the assigned pace simply becomes unachievable on a particular day.

Essentially, this affects you as the runner both physically and mentally. Benjamin Rapoport wrote that "Maximal Fuel Economy in endurance running is achieved at constant levels of exertion" in his study of metabolic factors that limit performance in marathon runners. Basically, running at uneven paces is far more fatiguing than running at a steady exertion state. Gentle fluctuations are expected, especially on a perfectly smooth route, but the device can aggravate the situation.

All of this tends to get into your head. It disconnects you from how your body is actually feeling and makes you think that you aren't achieving your goals (particularly if you keep getting the too slow beep). Mental strength, particularly in distance events, is such an overlooked factor. The last thing you need is a device acting as a mental anchor.

So what to do?

First, consider turning off the alerts and using a pace range as opposed to an exact speed. Most devices give you multiple ways of seeing your pace at a glance and allow you to set a range at which to run. This can help with unnecessary and discouraging beeps. The last thing you need is a nagging electronic criticism on a challenging workout.

Second, make sure you understand what pace you are looking at. Devices can measure a plethora of data such as overall average pace, lap average pace, active pace, and rolling time pace. Knowing what you're looking at lets you make successful adjustments on a workout or a race.

Third, consider running at an RPE (Rate of Perceived Effort). This helps in a multitude of ways. Running on a hot day, into a stiff wind, and up a hill is guaranteed to be more difficult work than the reverse, and your pace is going to reflect that. Knowing this lets you compare workouts on an equal footing. It also gets you more in tune with your body. You will start to feel what specific paces feel like by being more physically aware of your body's performance. Then a quick glance at your device acts as a conformation as opposed to a harness. Sensing these subtle changes puts you in the driver's seat of both your training and future races. One only has to look at some of the successes of various elite runners to find the proof. Trevor Hofbauer famously ditched technology in his buildup to become Canada's representative for Tokyo 2020. And Eliud Kipchoge was wearing a dated and relatively simple Garmin as recently as 2017 as arguably the best marathoner in the world while chasing the two-hour threshold. This is not a lecture to begin running with a dollar store stopwatch. Data these devices provide can give you an extra edge as you build for your next race. However, knowing what your device gives to your training and takes away will make you a more robust, happier, and more successful runner.

Written by Coach John Bird, WRTWC

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