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  • Scott Murray

activity tracker science


As always, if you are new to the channel/page and haven't already checked out the high volume, macro friendly recipe book then be sure to have a look.


Whether it's to directly support the channel or you genuinely love eating huge, tasty meals and don't ever want to be left feeling hungry on a diet ever again, the book is literally everything you will ever need.


Click HERE to see more :)


However, for now, much like I said in the video, here is the science explained about fitness trackers along with plenty of links to the papers used so you can read into it more if you're a nerd like me :)


ACCURACY FOR STEPS

Fitness trackers have shown to be quite accurate in tacking overall steps & distance covered (Evenson et al 2015). This can be highly advantageous in order to track non exercise activity thermogenesis (NEAT) as, by only standardising your physical activity and not STANDARDISING for NEAT you are almost “pissing into the wind” seeing as the latter contributes up to 50% of total daily energy expenditure (TDEE) vs the former contributing only 15-30% (Aragon et al 2017)


ACCURACY FOR ENERGY EXPENDITURE

In terms of heart rate, again, fitness trackers are quite accurate however where they are far LESS accurate (dependant on the model), is in their calculation for calories burned with studies showing an error of 27% for the Fitbit Surge and a whopping 93% for the PulseOn (Shcherbina et al 2017). This is likely down to their inability to take into account individual variations in metabolism, fitness level, type of exercise performed etc.


IMPACT ON MOTIVATION

As fitness trackers give you direct, objective data of your daily activities, they can be of great use for these who lack motivation with studies even showing people who wear them to have a greater self-efficacy towards exercise (Ridgers et al 2016, Gualtieri 2016). DOWNSIDES

Apart from being expensive, fitness trackers have also shown to be a unique predictor of eating disorders (Simpson, 2017) in that people who wear them are more inclined to adopt the mind-set of “train to eat” vs “eat to train”, focusing solely on kcal burn and feeling guilt/anxiety when they do not burn as many kcals or take as many steps as usual. Unfortunately, I can vouch for this as in the past (years ago), I did get slightly obsessed about the heart rate and kcal burn (OGs will know) thus resulting in a horrible relationship with diet and exercise.


TAKE-HOME MESSAGE

Overall, a watch is never going to be 100% accurate in telling you how intense you went, your heart rate, overall steps etc per day as there are too many variables that could influence the value shown. That being said however, the accuracy in their step count does seem meaningful enough to use them as a reliable tool for step tracking and standardising for NEAT. Furthermore, even if the watch is COMPLETELY inaccurate (like most cheap ones you get), the fat that it is CONSISTENTLY inaccurate is still a solid enough reason to use one however, if choosing to invest in one, don’t let it take over your life and/or alter the way you work out. The goal of a workout is to focus on progression vs kcal burn so take the values given for your training session with a pinch of salt and if you do find that it starts contributing to more stress/anxiety than anything, ditch it straight away before you become overly emotionally attached to it.


GOOD PAPERS FOR FURTHER RESEARCH

https://www.researchgate.net/publication/287482533_Systematic_review_of_the_validity_and_reliability_of_consumer-wearable_activity_trackers

https://pubmed.ncbi.nlm.nih.gov/28538708/

https://pubmed.ncbi.nlm.nih.gov/27881359/

https://pubmed.ncbi.nlm.nih.gov/27903490/

https://pubmed.ncbi.nlm.nih.gov/28214452/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6107736/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5920198/

https://bit.ly/2SEoFQ6

https://bjsm.bmj.com/content/54/6/332

https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0216891

https://www.nature.com/articles/s41746-020-0297-4

As always, thanks for the support and stay tuned for the vid on the channel soon


Scott

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