Posted On:
Tuesday, July 18, 2023
Updated On:
Tuesday, July 18, 2023

Coach Tip Tuesday: Fitness Devices are Not Smart...YOU Are

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The algorithm says "Good Morning!"

Raise your hand if you own a fitness device. Raise your hand if you own more than one fitness device. Raise your other hand if your first hand is wearing a fitness device.

You probably get my point…now, in 2023, almost everyone - athlete or not - owns some sort of device capable of tracking fitness and/or health-related data.  This week, I’m sharing an opinion that is countercultural to this new normalcy:

Fitness devices are not smart.  A fitness device is an inanimate object that is constructed of tangible materials; it does not have a brain or central nervous system.  Fitness devices record data points as programmed by the people who designed them.  Using those data points, many fitness devices deploy algorithms that are marketed as being able to tell the user about themselves.  Then, those algorithms are marketed as being an appropriate basis for making decisions in one’s life, whether it be in training or other health-related decisions.  But these devices and their algorithms - though designed by humans - are not smart.  YOU - the one who inhabits your body and who has a brain - YOU are the one who is smart.

What an Algorithm Actually Is

An algorithm is a process or set of rules to be followed in calculations or other problem-solving operations, especially by a computer.  By a computer.  Not by a human.  As it pertains to fitness devices, this set of rules and calculations used by the computer (which, as a reminder, doesn’t have a sentient brain) is based on a relatively narrow set of data.  Most of the data used is from studies conducted on middle-aged males.  Can more data points be entered into an algorithm?  Yes.  But the more variables that are entered into it, the more inaccurate it can be since it can’t actually decipher what applies for a specific human and what shouldn’t.

In this (fitness) space, fitness devices and their algorithms represent a simplification of how complex the human body actually is.  They represent an easy answer in the form of data and products so companies can manufacture, market, and sell these items to make a profit.  THe human body is one of the most complex systems we have.  To date, there isn’t a simple, condensed, packaged answer to how it works - let alone how it works optimally - even if we want that to be true.

I think that fitness devices and their algorithms are our current iteration of The Fountain of Youth.  Some form of The Fountain of Youth has existed in the human canon since at least the 5th Century BC, though it probably predates that since we lack recorded history for so much of our history as a species.  Fitness devices are our species’s current attempt to stave off aging, remain healthy and youthful, and quantify an intangible and mysterious part of our existence.  Humans have always craved and sought this, though how we have done so has morphed and evolved over the centuries.  In the 21st Century, fitness devices are our version of it.

The best athletes in the world do not base their training or race on fitness devices.  Yes, you will see many of them either wearing them or using them in some capacity.  But (Unpopular Opinion Warning) most of those athletes are visibly wearing them because they are paid to do so.  Sponsorships are one of the only ways endurance athletes can make a real living as professional athletes, and thus they will accept those sponsorships and wear devices because they are paid to.  But make no mistake about it: Those same athletes are not landing on the top of podiums because of those devices.  Those athletes are landing on the top of podiums because they are absolute masters of their craft and have some of the highest degrees of self-awareness out of all humans.  They know what their body needs to feel like; they do not rely on a device to tell them what to feel or how to train and race.

The Truth About Fitness Device Data

I have said (perhaps ad nauseam) over the years how we should exercise caution when interpreting the information that comes from fitness devices.  A device doesn’t change us; we change us.  The things that work in fitness and endurance sports are boring.  Companies market their products in a way that gamifies something that is ultimately very simple: If you want to see results in endurance sports - or anything else in life - you have to show up and do the work consistently.  You need to say no to some things so you have space to do the things that matter most to you.  You need to be focused and cannot attempt to multitask (which is impossible, no matter how much people might want or wish for that to be different).

I’ve also written countless comments in response to post-workout notes from athletes who are on Performance Coaching about how the data recorded from their workout wasn’t accurate or recorded properly.  When data isn’t recorded properly, it’s not usable and should be disregarded.  Period.  Full stop.  

Bad data is worse than no data.  (In this context, “bad data” means “inaccurate data.”)  This is true both for analysis and also due to the fact that my experience has shown me that people cannot actually disregard bad data.  They will let data - no matter what it is or if it’s true - impact their mood and/or how they feel about a workout and their training.  Worse, many athletes will let data from devices inform their opinions about themselves as a n athlete and - in the worst case scenario - how they view themselves as a human.  The number of times an athlete has told me that data has made them feel bad is too numerous to count.  Worst of all, most of the times when athletes have said this has been when it was clear that the data was inaccurate.

While this is by no means a complete or exhaustive list, here are some of the most common ways device data can be inaccurate:

  • GPS is not accurate for short distances or quick changes in direction.
  • Back-and-forths while running, cycling, or anything else in a small area will not record accurately.
  • GPS is not accurate for open water swimming.
  • At least 50% of open water swimming data is algorithmically generated.  When the athlete’s hand (device) is below the surface of the water, it cannot see GPS satellites.  So, the algorithm fills in those data gaps using its best guess of where you were and how fast you went there.
  • Open water swimming back and forth in a small area is exponentially more inaccurate because of the first point in this list.
  • How a device is worn or set up matters, and if it’s not worn or set up properly, it will not accurately record data.
  • Optical (wrist-based) heart rate monitors need to be worn tightly.  Honestly, the level of tightness needed for the most accurate data is a level of tightness that will feel uncomfortable to the wearer.
  • The accuracy of optical heart rate monitors is rooted in how clearly they can “see” through the wearer’s skin.  Darker skin tones are harder for these sensors to see through.
  • Electrical (chest-based) heart rate monitors are the most accurate heart rate monitors for all skin types and humans.  However, they need to be wet before they are put on.
  • Pedal-based power meters need to be installed to the proper level of torque.
  • All power meters should be calibrated before every single ride.  Neglect to do this, and algorithms do it for you with their best guesses at data.  (Spoiler: Accurate data isn’t based on guesses.)
  • GPS satellites need to be found before an outdoor workout is started in order to stand a chance at recording accurate pace data.
  • The further away from the heart you get, the harder it is to accurately measure the heart.
  • To date, the only fitness device that has been compared to actual echocardiogram heart rate data and validated is the Polar Heart Rate Monitor.

When I share these examples with athletes, a common response is, “That can’t be true, because why would they say it does what it does if it’s not accurate?”  Well, I’m here to tell you the hard reality: It is true, and companies market these devices and make these claims because they know it will entice you to buy them and that makes those companies money.

How to Wisely Implement Fitness Devices

Now, all is not lost.  I don’t actually think fitness devices are all bad; I just think how devout some people are to them is cause for concern.  There is a way to incorporate fitness devices and the data they record in a thoughtful, useful way.

#1 - Increase Self Awareness
One of the most important things a fitness device can do is to drive athlete self-awareness. Accurately recorded data that is interpreted in an honest manner can make an athlete aware of what they are doing and how they are actually performing. Over time, the athlete can become more aware of what things actually feel like in their own body and decrease their reliance on the device to tell them what they are doing and/or how they are feeling. (As noted earlier, this is exactly what professional and elite athletes do.)

#2 - Make Actual Behavioral Changes
Recording data just to record data is useless. Yet, that is exactly what so many athletes (and people) do. There are many, many people who wear devices that record how much they sleep, what their heart rate is, what their power is, how many steps they walk, and more. However, those same people do not make any changes in their behavior as a result of that data; they just record the data. The act of recording something is not actually doing something. It can, however, generate the false sensation of having done something real…and that’s what makes this so dangerous.

If you are going to spend money on a fitness device, it should be something that adds value to your life and it should be one that you are going to engage with in the following ways:

  1. Ensuring that you are accurately recording the data points.
  2. Deleting (or at minimum, disregarding) data sets that are known to be inaccurate.
  3. Spending the time to analyze the data points after they are recorded in a timely manner.
  4. Implementing changes based on those data points in a timely manner.
  5. Rinsing and repeating steps 3 and 4 as long as you own the device.

Making actual behavioral changes as a result of your data can help foster that self-awareness that we talked about earlier, and that is one of the most important tools in the Athlete’s Toolbelt for any athlete.  If you are unwilling or uninterested in that amount of focus, then honestly, save your money and don’t buy the device you’re considering.  It’s just not worth it.

#3 - Use in Coaching
If you work with a coach, recording data is extremely useful if your coach is not present with you during each of your workouts and races. In my work as an endurance coach, (accurate) data does give me context about the workout that the athlete completed. That being said, it’s not the be-all, end-all. I care far more about how the athlete felt in their body and in their mind than what the device says they did. Secondary to that subjective feedback, the most useful piece of data for me as a coach is heart rate (because that shows the body’s response to the work that the athlete was doing). Any other data points - pace, power, cadence - are nice, but are secondary to what the body’s response (heart rate) to the stimulus (workout) was when we’re talking about data. If the data is inaccurate, I don’t care a wink about it, and default to asking the athlete how they felt in their body for that workout and using only that for my feedback and analysis.

I use both data and the athlete’s subjective feedback to guide the questions I ask and the feedback I give on workouts.  It’s not uncommon for me to see something or interpret something that the athlete didn’t see or wasn’t aware of.  Leveraged this way, recording accurate data and working with a coach can help accomplish the most important of all things in endurance sports: Increasing athlete self-awareness.

The Moral of the Story

Do not yield your status as a sentient being and your superior brain (because it is superior - literally - to every other homo species that has lived on Earth thus far and is superior to any other living creature that has inhabited the planet) to a (very attractively designed) pile of plastic, metal, and glass.  Fitness devices are not smart; YOU are.  Think about why you’re wanting and/or using one and decide if it’s going to add actual value to your fitness journey.


Coach Laura Henry

Laura Henry is a Syracuse, NY-based coach who is a USA Triathlon Level II Long Course and Level II Paratriathlon Certified Coach, USA Cycling Level 2 Certified Coach, VFS Certified Bike Fitter, and has successfully completed NASM's Certified Personal Trainer course. Coach Laura is passionate about helping athletes of all ability levels reach their goals and has coached many athletes to success.

She can be reached at

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