‘Fat burning zones’ on much commercial gym equipment are not accurate apparently

The best heart rate for burning fat differs hugely between individuals and often does not align with the suggested “fat burning zone” on commercial gym equipment and exercise machines. Given the individual nature of “training zones” (and therefore fat metabolising zone) it is perhaps no great surprise that a generic setting on a machine will be…

The best heart rate for burning fat differs hugely between individuals and often does not align with the suggested “fat burning zone” on commercial gym equipment and exercise machines. Given the individual nature of “training zones” (and therefore fat metabolising zone) it is perhaps no great surprise that a generic setting on a machine will be wrong. Similar to setting your Max HR by subtracting your age from 220 whilst humming the national anthem and standing on one leg 😉

However I was interested to read an article on FitTechGlobal with a headline headline finding of a study by Icahn School of Medicine (ISM) at Mount Sinai, which researched exercise intensity and associated heart rate at which the body reaches its highest fat-burning rate during aerobic exercise.

It found that the “sweet spot” for optimising fat loss during workouts – often referred to as FATmax – is highly individual. No surprise there then!

Instead, the researchers said, clinical exercise testing – a diagnostic procedure to measure a person’s physiological response to exercise – may be a more useful tool to help individuals achieve intended fat loss goals.

The study’s lead author, Hannah Kittrell, a PhD candidate at ISM, said: “People with a goal of weight or fat loss may be interested in exercising at the intensity which allows for the maximal rate of fat burning. 

“Most commercial exercise machines offer a ‘fat-burning zone’ option, depending upon age, sex, and heart rate.

“However, the typically recommended fat-burning zone has not been validated, thus individuals may be exercising at intensities that are not aligned with their personalised weight loss goals.”

As part of the study, the researchers compared heart rate at FATmax, as measured during a clinical exercise test, to predicted heart rate at percentages of maximal effort within the typically recommended “fat-burning zone”.

In a sample of 26 individuals, the researchers found that there was poor agreement between measured and predicted heart rate, with a mean difference of 23 beats per minute between the two measures. 

This suggests that general recommendations for a “fat-burning zone” may not provide accurate guidance.

The study’s senior author, Girish Nadkarni, said: “We hope that this work will inspire more individuals and trainers to utilise clinical exercise testing to prescribe personalised exercise routines tailored to fat loss. It also emphasizes the role that data-driven approaches can have toward precision exercise.”

In addition to the commentary in the article, I would also remind people about the inherent error in inexpensive consumer heart rate monitors. Starting with the next to useless approach of wrist based measurement through to poorly fitted heart rate straps. Not to mention the error effect of a battery that is wearing out.

So the take away (I suggest) is that DONE PROPERLY using heart rate in training (be that fat loss or fitness) is valuable. However the scope for POOR MEASUREMENT and MISINTERPRETED DATA is significant.

Would you like some help figuring out how to make better use of heart rate data? Contact me for a 45min online consultation. Also don’t forget to visit myRunningStuff.com for all your run essentials to take your mind of inaccurate heart rate date!! 😉

Photo by Tima Miroshnichenko

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