The Accuracy of the Apple
Watch in Tracking Caloric
Expenditure
By: Ella Smith & Landry Schoennauer
What is the problem?
• Weight loss has become a much needed resource to help combat
obesity and activity trackers have become more and more popular
to help with these programs (Cheatam, 2018)
• Apple Watches are currently proven to be inaccurate in tracking
not just energy expenditure but also heart rate, steps, and minutes
of exercise (Germini, 2022; Kwon, 2021; Sun, 2023)
• The sensors on these watches are the inaccurate part of the
technology and there is yet to be a solution or design to help fix
this (Dimitritatos, 2020; O'Driscoll, 2018)
Purpose Statement
• Primary Purpose Statement: the purpose of this study is to examine the
accuracy of the Apple Watch compared to the gold
standard (metabolic cart) to measure calorie expenditure in
college students. We will compare the accuracy in two different
exercise intensities.
• Secondary Purpose Statement: The secondary purpose of this study is
to determine whether increasing exercise intensity does or does not
affect the accuracy of the Apple Watch in tracking calories.
• Exploratory: The purpose of this study is to explore the accuracy of
an Apple Watch worn by college aged students when doing two
different intensities of exercise.
Methods: Study Design
- Cross-sectional validation study, within-subjects design
- Data will be collected in one session to compare the Apple Watch
EE estimates with the metabolic cart across two intensities
Methods: Study Sample
- At least 20 healthy, college age adults (ages 18-25)
- Inclusion/Exclusion criteria: must have no prior health issues or risk
factors. Must regularly exercise at least 3x per week. College athletes
will be excluded from the study.
- Students will be recruited from SPU (and possibly other
local universities)
Methods: Measures
- Dependent variable = accuracy of tracking calorie expenditure from
Apple Watch
- Apple watch measures EE in kcals
- Metabolic cart measures true EE in kcals
- Independent variable = exercise intensity determined through treadmill
distance(km)/speed(km/h)/incline(% grade), and device type (Apple
Watch vs metabolic cart)
- Additionally, we may include a survey to assess the relative reliance on
tracking calories with the Apple Watch in college students
Methods: Procedures
1. Orientation: participants will sign an informed consent form and complete
a short health screening questionnaire. Personal information will be
recorded, including height, weight, age, and sex. The metabolic cart mask
will be fitted to the participant to ensure an airtight seal.
2. Exercise trial 1: walk one mile on treadmill at 4 km/hour
3. Exercise trial 2: run/jog one mile on treadmill at 7 km/hour
Participants will complete a 5-minute standardized warm-up before trial 1 and
will have a 10-minute rest period between the first and second trial.
Prior to the session participants will be instructed to not consume any food or
drink 2 hours prior to the session, not consume caffeine or other stimulants 24
hours prior to the session, not engage in vigorous activity 24 hours before
session, and get at least 6-8 hours of sleep the night prior.
Methods: Main Method of Control
• Standardized pre-test protocol; participants will all have the same
fasting/exercise/caffeine window. This will hopefully avoid
variability in participants' metabolism. Each of these factors could
impact the metabolism of the participant and affect the results of
the study.
References
• Cheatham, S., Stull, K., M Fantigrassi, & Motel, I. (2018). The efficacy of wearable activity tracking technology as part of a weight loss
program: a systematic review. The Journal of Sports Medicine and Physical Fitness, 58(4), 534–548. https://doi.org/10.23736/S00224707.17.07437-0
• Dimitritatos, S.M., German, J.B., & Schafer, S.E. (2020). Wearable technology to quantify the nutritional intake of adults: Validation
Study. JMIR Publications, 8(7). https://doi.org/10.2196/16405
• Germini, F., Noronha, N., Debono, V.B., Philip, B.A., Pete, D., Navarro, T., Keepanasseril, A., Parpia, S., de Wit, L., & Lorio, A. (2022).
Accuracy and acceptability of wrist-wearable activity-tracking devices: systematic review of the literature. JMIR Publications,
24(1). https://doi.org/10.2196/30791
• Kwon, S., Kim, Y., Bai, Y., Burns, R. D., Brusseau, T. A., & Byun, W. (2021). Validation of the Apple Watch for Estimating Moderate-toVigorous Physical Activity and Activity Energy Expenditure in School-Aged Children. Sensors, 21(19), 6413.
https://doi.org/10.3390/s21196413
• O’Driscoll, R., Turicchi, J., Beaulieu, K., Scott, S., Matu, J., Deighton, K., Finlayson, G., & Stubbs, J. (2018). How well do activity monitors
estimate energy expenditure? A systematic review and meta-analysis of the validity of current technologies. British Journal of Sports
Medicine, 54(6), bjsports-2018-099643. https://doi.org/10.1136/bjsports-2018-099643
• Sun, X., Wang, Z., Fu, X. K., Zhao, C., Wang, F., & He, H. (2023). Validity of Apple Watch 6 and Polar A370 for monitoring energy
expenditure while resting or performing light to vigorous physical activity. Journal of Science and Medicine in Sport, 26(9), 482–486.
https://doi.org/10.1016/j.jsams.2023.07.005