Cited by 118Physical Activity and HealthContext-Aware Activity Recognition SystemsMobile Health and mHealth Applications

Assessment of laboratory and daily energy expenditure estimates from consumer multi-sensor physical activity monitors

Open access
Chowdhury, Enhad A., Western, Max J., Nightingale, Thomas E., Peacock, Oliver J., Thompson, Dylan·2017·PLOS ONE

Abstract

Wearable physical activity monitors are growing in popularity and provide the opportunity for large numbers of the public to self-monitor physical activity behaviours. The latest generation of these devices feature multiple sensors, ostensibly similar or even superior to advanced research instruments. However, little is known about the accuracy of their energy expenditure estimates. Here, we assessed their performance against criterion measurements in both controlled laboratory conditions (simulated activities of daily living and structured exercise) and over a 24 hour period in free-living conditions. Thirty men (n = 15) and women (n = 15) wore three multi-sensor consumer monitors (Microsoft Band, Apple Watch and Fitbit Charge HR), an accelerometry-only device as a comparison (Jawbone UP24) and validated research-grade multi-sensor devices (BodyMedia Core and individually calibrated Actiheart™). During discrete laboratory activities when compared against indirect calorimetry, the Apple Watch performed similarly to criterion measures. The Fitbit Charge HR was less consistent at measurement of discrete activities, but produced similar free-living estimates to the Apple Watch. Both these devices underestimated free-living energy expenditure (-394 kcal/d and -405 kcal/d, respectively; P<0.01). The multi-sensor Microsoft Band and accelerometry-only Jawbone UP24 devices underestimated most laboratory activities and substantially underestimated free-living expenditure (-1128 kcal/d and -998 kcal/d, respectively; P<0.01). None of the consumer devices were deemed equivalent to the reference method for daily energy expenditure. For all devices, there was a tendency for negative bias with greater daily energy expenditure. No consumer monitors performed as well as the research-grade devices although in some (but not all) cases, estimates were close to criterion measurements. Thus, whilst industry-led innovation has improved the accuracy of consumer monitors, these devices are not yet equivalent to the best research-grade devices or indeed equivalent to each other. We propose independent quality standards and/or accuracy ratings for consumer devices are required.

AI snapshot

Written from the paper’s full text.

TL;DR

Consumer multi-sensor activity monitors varied widely in energy expenditure accuracy; Apple Watch and Fitbit Charge HR gave closer free-living estimates than Microsoft Band and Jawbone UP24, but all consumer devices underestimated daily energy expenditure and none were equivalent to the reference. The authors conclude independent quality standards or accuracy ratings are needed.

Key findings

  • In free-living conditions, Apple Watch and Fitbit Charge HR underestimated daily energy expenditure by -394 ± 970 kcal/d and -405 ± 944 kcal/d, respectively, while Microsoft Band and Jawbone UP24 substantially underestimated it (-1128 kcal/d and -998 kcal/d, respectively, in the abstract; results report -1123 ± 1235 and -998 ± 1153 kcal/d; P<0.01).
  • None of the consumer devices were deemed equivalent to the reference method for daily energy expenditure; only the research-grade Sensewear/BodyMedia device fell within the proposed ±10% equivalence zone.
  • In laboratory assessments, Apple Watch had the lowest mean absolute percent error among consumer devices (27% across activities; Actiheart 20%), while Fitbit Charge HR was less consistent for discrete activities but produced similar free-living estimates to Apple Watch.
  • For all devices, there was a tendency for negative bias with greater daily energy expenditure, and more sensors did not guarantee better accuracy (e.g., Microsoft Band underpredicted despite multiple sensors).

Methods

  • Thirty adults (15 men, 15 women; mean ± SD age 27 ± 6 y, BMI 23.4 ± 2.5 kg/m²) wore Apple Watch, Microsoft Band, Fitbit Charge HR, Jawbone UP24, BodyMedia Core, and individually calibrated Actiheart.
  • Laboratory validation used two blocks—24-min activities of daily living (typing, dishwasher, sweeping, stairs) and 64-min exercise (walk, loaded walk, cycle, jog)—compared with COSMED K4b2 indirect calorimetry; free-living validation used a minimum 36 h wear to capture one full calendar day, with individually calibrated Actiheart as criterion.
  • Analysis included Bland-Altman bias and 95% limits of agreement, mean signed/absolute error, repeated measures ANOVA with Holm-Bonferroni adjustment, and equivalence testing against ±10% of the criterion mean.

Limitations

  • Stated: the sample was relatively young, healthy, and active; devices were assessed “out of box,” so additional calibration with prolonged wear may improve accuracy; the importance of specific exercise modes is unknown; possible lag in device detection could not be conclusively established; longer activity durations, other target groups, longer free-living periods, and doubly labelled water as a criterion are needed.
  • Stated: manufacturers do not release algorithms, limiting explanation of results, and commercial devices did not readily allow raw energy expenditure data export.
  • Evident: the small sample (n=30) and contrived laboratory activities may not represent real-life activity distribution; the free-living criterion was Actiheart rather than doubly labelled water, which the paper acknowledges as ideal.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1371/journal.pone.0171720

Cites

49 of 49 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

0 of 36 cited sources checked · 0 supported · 0 flagged

  • Findingown data

    The Jawbone UP24 substantially underestimated free-living energy expenditure by 998 kcal/d (P<0.01).

    “and accelerometry-only Jawbone UP24 devices underestimated most laboratory activities and substantially underestimated free-living expenditure (-1128 kcal/d and -998 kcal/d, respectively; P<0.01).”
    Quote in the paperSubstantial claim
  • Findingown data

    For all devices, there was a tendency for negative bias with greater daily energy expenditure.

    “For all devices, there was a tendency for negative bias with greater daily energy expenditure.”
    Quote in the paperSubstantial claim
  • Findingown data

    The Microsoft Band underestimated most laboratory activities.

    “The multi-sensor Microsoft Band and accelerometry-only Jawbone UP24 devices underestimated most laboratory activities and substantially underestimated free-living expenditure (-1128”
    Quote in the paperSubstantial claim
  • Findingown data

    The Microsoft Band substantially underestimated free-living energy expenditure by 1128 kcal/d (P<0.01).

    “The multi-sensor Microsoft Band and accelerometry-only Jawbone UP24 devices underestimated most laboratory activities and substantially underestimated free-living expenditure (-1128”
    Quote in the paperSubstantial claim
  • Findingown data

    The Apple Watch underestimated free-living energy expenditure by 394 kcal/d (P<0.01).

    “Both these devices underestimated free-living energy expenditure (-394 kcal/d and -405 kcal/d, respectively; P<0.01).”
    Quote in the paperSubstantial claim
  • May combine two claims. 10
  • Classified as probably not a substantial claim. 6
  • May combine two claims.

    Findingown data

    All consumer devices produced significantly different free-living energy expenditure estimates from the research-grade devices, which were not different from each other.

    “Pairwise comparisons indicated that all of the consumer devices produced significantly different estimates from the research grade devices (which were not different from each other).”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingown data

    The Actiheart had the smallest limits of agreement of any device observed, with an absolute bias of -0.6 kcal/min and 95% limits of agreement of ±2.5 kcal/min.

    “Of the research grade wearable monitors, absolute bias ± 95% LoA values were 0.6 ± 3.8 kcal/min for the Bodymedia Armband with the smallest limits of agreement of any device observed for the Actiheart (-0.6 ± 2.5 kcal/min).”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingown data

    The research-grade Bodymedia device had similar limits of agreement to the Apple and Fitbit devices but lower mean bias (-66 ± 965 kcal/d) compared to individually-calibrated Actiheart.

    “For reference, the research grade Bodymedia device had similar limits of agreement to the Apple and Fitbit devices but with lower mean bias when compared to individually-calibrated Actiheart™ (-66 ± 965 kcal/d).”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingown data

    Each individual device was significantly different (p < 0.01) from every other device, except for the comparisons between Microsoft vs. Jawbone, Fitbit vs. Apple and Bodymedia vs. Actiheart.

    “Each individual device is significantly different p < 0.01 from every other device, except for the comparisons between Microsoft vs. Jawbone, Fitbit vs. Apple and Bodymedia vs. Actiheart.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingnone given

    None of the commercial devices tested readily allowed exporting of the raw energy expenditure data for detailed interrogation.

    “Unfortunately, none of the commercial devices tested readily allowed exporting of the raw energy expenditure data for detailed interrogation that might be useful for research/health applications.”
    Quote in the paperNot a substantial claim
  • Classified as probably not a substantial claim.

    Study design and conductnone given

    The COSMED K4b2 unit was calibrated prior to each session according to manufacturer's instructions.

    “The unit was calibrated prior to each session according to manufacturer’s instructions.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Premisecitation

    The Actiheart has previously been validated against doubly labelled water and used as a criterion measure of free-living energy expenditure in epidemiology studies.

    “The Actiheart™ has previously been validated against doubly labelled water [24,26,27] and has been used as a criterion measure of free-living energy expenditure in epidemiology studies [35].”
    Quote in the paperNot a substantial claim0 of 4 sources checked
    • cites [24] S Brage, 2015, Estimation of Free-Living Energy Expenditure by Heart Rate and Movement Sensing: A Doubly-Labelled Water Study, PLoS One source

      Not checked in the free run.

    • cites [26] FK Assah, 2011, Accuracy and validity of a combined heart rate and motion sensor for the measurement of free-living physical activity energy expenditure in adults in Cameroon, Int J Epidemiol source

      Not checked in the free run.

    • cites [27] C Villars, 2012, Validity of combining heart rate and uniaxial acceleration to measure free-living physical activity energy expenditure in young men, J Appl Physiol (1985) source

      Not checked in the free run.

    • cites [35] T Peters, 2012, Validity of a short questionnaire to assess physical activity in 10 European countries, Eur J Epidemiol source

      Not checked in the free run.

  • May combine two claims.

    Study design and conductcitation

    The COSMED K4b2 portable metabolic system has been shown to be reliable and valid for measuring energy expenditure.

    “This device has been shown to be both reliable and valid [30,31], and has also been used previously to determine criterion energy expenditure [28,32–34].”
    Quote in the paperSubstantial claim0 of 6 sources checked
    • cites [30] JE McLaughlin, 2001, Validation of the COSMED K4 b2 portable metabolic system, Int J Sports Med source

      Not checked in the free run.

    • cites [31] R Duffield, 2004, Accuracy and reliability of a Cosmed K4b2 portable gas analysis system, J Sci Med Sport source

      Not checked in the free run.

    • cites [28] SE Crouter, 2008, Accuracy of the Actiheart for the assessment of energy expenditure in adults, Eur J Clin Nutr source

      Not checked in the free run.

    • cites [32] D Thompson, 2006, Assessment of low-to-moderate intensity physical activity thermogenesis in young adults using synchronized heart rate and accelerometry with branched-equation modeling, J Nutr source

      Not checked in the free run.

    • cites [33] TE Nightingale, 2014, Predicting physical activity energy expenditure in manual wheelchair users, Med Sci Sports Exerc source

      Not checked in the free run.

    • cites [34] DK Spierer, 2011, A comparison of energy expenditure estimates from the Actiheart and Actical physical activity monitors during low intensity activities, walking, and jogging, Eur J Appl Physiol source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    BodyMedia SenseWear accurately measures energy expenditure relative to criterion measures.

    “Previous research has shown that BodyMedia SenseWear accurately measures energy expenditure relative to criterion measures [11,20,21] and has been used to quantify physical activity and energy expenditure in experimental trials [37,38].”
    Quote in the paperNot a substantial claim0 of 5 sources checked
    • cites [11] JM Lee, 2014, Validity of consumer-based physical activity monitors, Med Sci Sports Exerc source

      Not checked in the free run.

    • cites [20] DL Johannsen, 2010, Accuracy of armband monitors for measuring daily energy expenditure in healthy adults, Med Sci Sports Exerc source

      Not checked in the free run.

    • cites [21] MA Calabro, 2014, Validity of physical activity monitors for assessing lower intensity activity in adults, Int J Behav Nutr Phys Act source

      Not checked in the free run.

    • cites [37] OJ Peacock, 2015, Multidimensional individualised Physical ACTivity (Mi-PACT)—a technology-enabled intervention to promote physical activity in primary care: study protocol for a randomised controlled trial, Trials source

      Not checked in the free run.

    • cites [38] DS Bond, 2014, B-MOBILE—a smartphone-based intervention to reduce sedentary time in overweight/obese individuals: a within-subjects experimental trial, PLoS One source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Individual calibration improves Actiheart energy expenditure prediction in free-living and laboratory settings.

    “Individual calibration has been shown to improve energy expenditure prediction in free-living [24,26,27] and laboratory settings [23,25].”
    Quote in the paperNot a substantial claim0 of 5 sources checked
    • cites [24] S Brage, 2015, Estimation of Free-Living Energy Expenditure by Heart Rate and Movement Sensing: A Doubly-Labelled Water Study, PLoS One source

      Not checked in the free run.

    • cites [26] FK Assah, 2011, Accuracy and validity of a combined heart rate and motion sensor for the measurement of free-living physical activity energy expenditure in adults in Cameroon, Int J Epidemiol source

      Not checked in the free run.

    • cites [27] C Villars, 2012, Validity of combining heart rate and uniaxial acceleration to measure free-living physical activity energy expenditure in young men, J Appl Physiol (1985) source

      Not checked in the free run.

    • cites [23] S Brage, 2007, Hierarchy of individual calibration levels for heart rate and accelerometry to measure physical activity, J Appl Physiol source

      Not checked in the free run.

    • cites [25] TE Nightingale, 2015, Predicting physical activity energy expenditure in wheelchair users with a multisensor device, BMJ Open Sport & Exercise Medicine source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    The research devices BodyMedia Core and Actiheart have been extensively validated and shown to accurately predict energy expenditure.

    “These research devices (BodyMedia Core and Actiheart™) have been extensively validated and shown to accurately predict energy expenditure [11,20–28].”
    Quote in the paperSubstantial claim0 of 10 sources checked
    • cites [11] JM Lee, 2014, Validity of consumer-based physical activity monitors, Med Sci Sports Exerc source

      Not checked in the free run.

    • cites [20] DL Johannsen, 2010, Accuracy of armband monitors for measuring daily energy expenditure in healthy adults, Med Sci Sports Exerc source

      Not checked in the free run.

    • cites [21] MA Calabro, 2014, Validity of physical activity monitors for assessing lower intensity activity in adults, Int J Behav Nutr Phys Act source

      Not checked in the free run.

    • cites [22] S Brage, 2005, Reliability and validity of the combined heart rate and movement sensor Actiheart, Eur J Clin Nutr source

      Not checked in the free run.

    • cites [23] S Brage, 2007, Hierarchy of individual calibration levels for heart rate and accelerometry to measure physical activity, J Appl Physiol source

      Not checked in the free run.

    • cites [24] S Brage, 2015, Estimation of Free-Living Energy Expenditure by Heart Rate and Movement Sensing: A Doubly-Labelled Water Study, PLoS One source

      Not checked in the free run.

    • cites [25] TE Nightingale, 2015, Predicting physical activity energy expenditure in wheelchair users with a multisensor device, BMJ Open Sport & Exercise Medicine source

      Not checked in the free run.

    • cites [26] FK Assah, 2011, Accuracy and validity of a combined heart rate and motion sensor for the measurement of free-living physical activity energy expenditure in adults in Cameroon, Int J Epidemiol source

      Not checked in the free run.

    • cites [27] C Villars, 2012, Validity of combining heart rate and uniaxial acceleration to measure free-living physical activity energy expenditure in young men, J Appl Physiol (1985) source

      Not checked in the free run.

    • cites [28] SE Crouter, 2008, Accuracy of the Actiheart for the assessment of energy expenditure in adults, Eur J Clin Nutr source

      Not checked in the free run.

  • May combine two claims.

    Interpretationown data

    Consumer multi-sensor devices are not yet equivalent to the best research-grade devices or to each other.

    “Thus, whilst industry-led innovation has improved the accuracy of consumer monitors, these devices are not yet equivalent to the best research-grade devices or indeed equivalent to each other.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Premisecitation

    Resting metabolic rate is a substantial contributor to total energy expenditure, particularly with lower levels of activity, and is a broadly predictable component of energy expenditure.

    “As a substantial contributor to total energy expenditure (particularly with lower levels of activity) will be RMR, which is a broadly predictable component of energy expenditure [42], the greater accuracy for individuals with lower energy expenditure is unsurprising.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [42] D Frankenfield, 2005, Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review, J Am Diet Assoc source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning

    Laboratory assessments can produce data about specific activities which is useful for individuals interested in measuring a particular activity.

    “Laboratory assessments can produce data about specific activities which is useful for individuals interested in measuring a particular activity (e.g., someone taking up jogging wanting to assess energy expenditure during running).”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S2 (checkable).

    Interpretationcitation

    It is beneficial to assess prolonged wear in free-living conditions in addition to laboratory assessments of monitor performance for specific activities.

    “Therefore, it is beneficial to assess prolonged wear in free-living conditions in addition to laboratory assessments of monitor performance for specific activities.”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: The specifics of any given activity protocol, including the present study's own protocol, is unlikely to represent the distribution and importance of various activities in normal life.
  • May combine two claims.

    Interpretationreasoning

    Laboratory and free-living assessments both give valuable but unique information with which to assess monitor performance in different contexts.

    “Laboratory and free-living assessments both give valuable but unique information with which to assess monitor performance in different contexts.”
    Quote in the paperNot a substantial claim
16 of 16
  • The paper relies on this without support.

    There has been no examination of other activities of daily living or daily energy expenditure estimates of the next generation of sophisticated multi-sensor devices including those from large technology companies such as Apple.

    “However, there has been no examination of other activities of daily living or daily energy expenditure estimates of the next generation of sophisticated multi-sensor devices including those large technology companies such as Apple.”
  • The paper relies on this without support.

    The latest generation of consumer devices share similar technology as established multi-sensor devices used in research studies.

    “This step-change in consumer monitor sophistication has resulted in the latest generation of consumer devices sharing similar technology as established multi-sensor devices used in research studies.”
  • The paper relies on this without support.

    Little is known about the accuracy of energy expenditure estimates from consumer multi-sensor physical activity monitors.

    “However, little is known about the accuracy of their energy expenditure estimates.”
  • The authors state this as an assumption.

    Resting energy expenditure estimates are relatively similar between devices.

    “Assuming relative similarity of resting energy expenditure estimates between devices, this variance in total energy expenditure estimates between devices suggests that the measurement of physical activity per se is more variable than the estimation of total energy expenditure would suggest.”
  • The paper relies on this without support.

    This is the first examination of these consumer multi-sensor devices in both laboratory and free-living settings.

    “To our knowledge, this is the first examination of these consumer multi-sensor devices in both laboratory and free-living settings.”
  • The paper relies on this without support.

    Manufacturers do not release the algorithms used in estimation of energy expenditure.

    “Perhaps understandably, manufacturers do not release the algorithms used in estimation of energy expenditure.”
  • The paper relies on this without support.

    The specifics of any given activity protocol, including the present study's own protocol, is unlikely to represent the distribution and importance of various activities in normal life.

    “Furthermore, the specifics of any given activity protocol (including our own) is unlikely to represent the distribution and importance of various activities in normal life.”
7 of 7

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • The two devices showed reasonable accuracy in HR and EE estimations under certain exercise conditions.

    “Similar to previous studies [13,28,30-32], we found reasonable accuracy in HR and EE estimations for these 2 devices under certain exercise conditions.”

    From Accuracy of Wrist-Worn Activity Monitors During Common Daily Physical Activities and Types of Structured Exercise: Evaluation Study (2018) · cites this paper as [13]

    The Results (Laboratory validation; page unavailable) report activity-specific energy-expenditure errors for the Apple Watch and Fitbit Charge HR, supporting reasonable EE accuracy under some exercise conditions. The Methods (Statistical analysis; page unavailable) compare device EE estimates with criterion EE measurements, but our copy does not report a validation of the devices’ HR-estimation accuracy. (LLM, conf=0.88)

    Experimental — accuracy not yet measured
  • Nine studies (22 comparisons) examined energy expenditure in free-living settings compared with doubly labeled water and accelerometry.

    “Nine studies (22 comparisons) examined energy expenditure in free-living settings compared with the criterion measures of doubly labeled water [104] and accelerometry [29,49,79,101,131,172,174,175].”

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Microsoft Band daily bias differs between abstract and results

    Minor

    The abstract reports a free-living bias of −1128 kcal/d for the Microsoft Band, while the results report −1123 kcal/d for the same device.

1 of 1

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Authors
Chowdhury, E. A., Western, M. J., Nightingale, T. E., Peacock, O. J., & Thompson, D.
Affiliations
University of Bath (GB)
Corresponding author
Thompson, Dylan
Venue
PLOS ONE
Published
2017-02-24
Volume
12
Issue
2
Pages
e0171720
ISSN
1932-6203 (ISSN-L)
OpenAlex
W2589673251
Cited by
118
References
49
Citations by year
2026: 6 · 2025: 10 · 2024: 10 · 2023: 7 · 2022: 11 · 2021: 10 · 2020: 16 · 2019: 23 · 2018: 17 · 2017: 8
FWCI
12.95
Type
journal article
Language
en
Open access
Locations
  • PLoS ONE (publishedVersion, cc-by)
  • Europe PMC (PubMed Central) (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • Pure (University of Bath) (publishedVersion, cc-by)
  • The University of Bath Online Publications Store (The University of Bath) (submittedVersion, cc-by)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
  • Figshare (submittedVersion, cc-by)
  • University of Birmingham Research Portal (University of Birmingham) (submittedVersion, cc-by)
Funders
National Prevention Research Initiative (MR/J00040X/1)
Topics
  • Health Sciences › Medicine › Physiology › Physical Activity and Health
  • Physical Sciences › Computer Science › Computer Vision and Pattern Recognition › Context-Aware Activity Recognition Systems
  • Health Sciences › Health Professions › General Health Professions › Mobile Health and mHealth Applications
Keywords
energy expenditure estimation, consumer wearable devices, device validation, Apple Watch, Actiheart, accelerometry, indirect calorimetry, free-living energy expenditure, activities of daily living, structured exercise
MeSH terms
Fitness Trackers, Adult, Calorimetry, Indirect, Energy Metabolism, Female, Humans, Male, Reference Values, Exercise, Accelerometry

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