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The emperor’s new biomarker? Another wearable for us to evaluate

by R.Donald


The bio-hacking community was disrupted last week by news of a novel biomarker – one measured by a wearable on the temple. It’s aptly named ‘Entropy’, apt because of the chaos its revelation unleashed. The name, however, is not apt for what it’s purported to measure: amount of energy consumed by the body. So, it shows a minimal value during periods of deep rest (sleep or deep meditation), and a maximal reading during periods of intense activity.

Individuals with some knowledge of thermodynamics will point out the difference between energy and entropy. Measuring energy expenditure is not the same as measuring entropy – a sophisticated concept that can be approximated as the degree of randomness or chaos within a system. Of course, ‘Entropy’ as a biomarker name is much more marketable than, say, ‘Energy,’ or any synonymous term such as ‘Calorie’.

‘Enthalpy,’ a thermodynamic property that measures the total heat content of a system, would have been technically flawless, but is commercially hopeless. Possibly, terms such as ‘Fire,’ ‘Shakti,’ ‘Prana,’ or the slang-ier ‘Josh’ could have fitted the bill.

More than the nomenclature, attention should, however, be directed to the claims made around measurement accuracy and possible benefits of measuring this marker. For Entropy, this data is still in early stages.

I have written previously about the lack of rigorous scientific evidence linking wearables use and real physiological improvements. Common wearables worn simply as wrist bands or body bands track heart/pulse rate metrics, sleep patterns, breath patterns. Continuous glucose monitoring (CGM) has gained traction even with its requirement to insert a tiny filament into the skin. There is a wide range of accuracy in wearables.

My experience has been that even a basic measure, such as heart rate (as measured by the wrist pulse rate), has a massive error rate (of up to 20%) when compared with the pulse rate measured with a finger-on-the-pulse method (either on wrist or neck). Any calculated metric such as heart rate variability based on these measured base values will carry along the error rates.