Calorie Expenditure: What is the Real Number?

I’d like to think of myself as an explorer, a fitness centre explorer. Any chance I get to go into a new facility I am giddy and excited like a child on Christmas morning. I like to explore gyms from large municipal facilities to hotel fitness rooms. The rush of seeing shiny equipment and learning about innovative programs is fun for me. I always want to know what physical activity opportunities are out there from both a business and personal curiosity perspective.

About six months ago, I was driving by a new fitness centre and decided to go in to learn about what they had to offer. I always enter as a “lay” person and inquire about membership, ask for a tour and inquire about programs. I ask about spin/indoor cycling classes. In this one particular facility I inquired and the customer service representative was happy to tell me about their indoor cycling classes. She proceeded to tell me that a class can “burn up to 1400 calories” in 60 minutes. I tried not to let my face warp into an inquisitors’ expression, as I asked myself, what is the real number of calories one burns in an indoor cycling class?

Well, one of my favourite resources was published in the journal Medicine and Science Sport and Exercise in 2000. Barbara Ainsworth has done extensive research on energy expenditure and physical activity and published the Compendium of Physical Activity. It outlines the metabolic equivalent (MET) for a lengthy list of activities. And we can use her work to help determine the answer...or at least a range of answers.

First and foremost, we’ll assume your average cycle participant is 150 lbs (68 kg). Based on Ainsworth’s Compendium, your average cycle participant uses the following METs and estimated calorie expenditure per hour based on different drills or power outputs:

Based on the calculations, an average indoor cycling participant doesn’t come near to what was quoted by the customer service representative, unless your cycle participants on average are 440 lbs (200 kg), and they are riding at a moderate effort. Are you surprised by the result? It turns out that body weight factors into the way energy expenditure is calculated and the results end up being highly personalized.

As certified fitness leaders, it is our responsibility to provide our participants with correct information. Take the time to let your participants know their efforts are great but may not be an absorptive amount of calories that sometimes can be presented when pitching a program or new type of fitness class. Keep it realistic and maybe not bother quoting calorie expenditure. As we all know, there are many other benefits to riding that just burning calories!

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