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Cycle with Sean Kelly at SportActive

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How Accurate is Your Calorie Burn Device?

Thanks to the rise of electronic devices we have a plethora of ways of measuring calorie burn when on two wheels. The more sophisticated devices can measure distance and show GPS information as well as monitor your heart rate.

Studies, however, are showing that the majority of devices are inaccurate in terms of measuring calorie burn when cycling.

Take this Stanford University study that put several devices through their paces. The results showed just how inaccurate wrist worn devices were when measuring calorie burn. Devices included:

  • Apple Watch
  • Fitbit Surge
  • Mio Alpha 2
  • Basis Peak
  • Microsoft Band
  • PulseOn
  • Samsung Gear S2

The best device was the Apple Watch which was 23% inaccurate in measuring how many calories were burned for different activities including walking, running, cycling, and sitting. The least accurate device was 93% inaccurate. One of the authors of the study advised against working out how many doughnuts to eat based on calorie burn readings using these devices.

Strava and similar apps may fair a little better but taking the calorie burn as a very rough guide is prudent.

This begs the question, why are the popular devices inaccurate?

SportActive Cycling Holidays and Training Camps a picture of a post run recorded on a fitness watch device According to a Stanford University Study, wearables are not the best at measuring calorie burn.

Cycling Calorie Burn Factors

The reasons for the inaccuracy of the devices are many. Many use the Metabolic Equivalent of Task (MET) formula to work out calorie burn when cycling. This takes your weight and an estimate of your energy expenditure.

What it doesn’t take into account are individual factors such as how fit you are. So let’s take a 68 kilo rider cycling around 15 kph. The MET score is about 8 and once the numbers are crunched your average wearable calorie burn reader is going to state that you are burning around 540 calories per hour.

However, if you’re in good condition that effort level is going to be a lot less and as such, the figure is going to be misleading. If you consider you burn 1 MET watching TV which equates to 68 calorie burn for effectively doing nothing, you can see the margin of error is pretty big.

Improving Cycling Calorie Burn Reader Accuracy

There are ways you can improve the calorie burn by feeding it more information. Try putting in your age, height, weight, gender, and max heart rate and this should improve the algorithms powering your device. Syncing a chest-worn heart rate monitor should improve your overall accuracy too.

Is there a Way of Accuraty Measuring Calorie Burn When Cycling?

Happily, yes there is. The answer is to use a power meter as these devices measure kilojoules which is the amount of work you produce to turn the pedals. As kilojoules more or less equate to a 1:1 ratio with calorie burn, you get a far more accurate picture of calorie burn with a power meter. So an 800 kilojoule measurement equates to an 800 calorie burn with a margin of error of about 5%.

Further, power meters help you train more effectively and help overall performance when combined with cycling training zones.

SportActive cyclists crossing the finishing line of the Mallorca 312 Power meters measure calorie burn with a high degree of accuracy

Losing Weight Through Cycling

If your aim is to lose weight through cycling remember number crunching is not all there is to it. Using training techniques such as high intensity interval training to increase your lactate threshold and VO2 Max keeps you in an aerobic state for longer, resulting in greater calorie burn.

Diet and Nutrition

As well as training hard, diet and nutrition are two areas to focus on for better cycling. This isn’t just fuelling on the bike, but what you eat off it. Keeping fat in your diet at around 35% and eating plenty of vegetables and fruit tends to have good results.

As such, keep cycling and training, ensuring you have two good hard sessions featuring either HIIT or hills, and you’ll be maintaining and improving your condition.

And above all don’t obsess over the numbers as it will do you no good.

Keep cycling.

Submitted: 29/8/22

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