OBJECTIVES: Regular physical activity (PA) and reduced sedentary behaviour (SB) have been associated with positive health outcomes, but many older adults do not comply with the current recommendations. Sensor-triggered ecological momentary assessment (EMA) studies allow capturing real-time data during or immediately after PA or SB, which can yield important insights into these behaviours. Despite the promising potential of sensor-triggered EMA, this methodology is still in its infancy. Addressing methodological challenges in sensor-triggered EMA studies is essential for improving protocol adherence and enhancing validity. Therefore, this study aimed to examine (1) the patterns in sensor-triggered EMA protocol adherence (eg, compliance rates), (2) the impact of specific settings (eg, event duration) on the number of prompted surveys, and (3) participants' experiences with engaging in a sensor-triggered EMA study. DESIGN: Two longitudinal, sensor-triggered EMA studies-one focused on PA and the other on SB-were conducted using similar methodologies from February to October 2022. Participants' steps were monitored for seven days using a Fitbit activity tracker, which automatically prompted an EMA survey through the HealthReact smartphone application when specified (in)activity thresholds were reached. After the monitoring period, qualitative interviews were conducted. Data from both studies were merged. SETTING: The studies were conducted among community-dwelling Belgian older adults. PARTICIPANTS: The participants had a median age of 72 years, with 54.17% being females. The PA study included 88 participants (four dropped out), while the SB study included 76 participants (seven dropped out). PRIMARY AND SECONDARY OUTCOME MEASURES: Descriptive methods and generalised logistic mixed models were employed to analyse EMA adherence patterns. Simulations were conducted to assess the impact of particular settings on the number of prompted EMA surveys. Additionally, qualitative interview data were transcribed verbatim and thematically analysed using NVivo. RESULTS: Participants responded to 81.22% and 79.10% of the EMA surveys in the PA and SB study, respectively. The confirmation rate, defined as the percentage of EMA surveys in which participants confirmed the detected behaviour, was 94.16% for PA and 72.40% for SB. Logistic mixed models revealed that with each additional day in the study, the odds of responding to the EMA survey increased significantly by 1.59 times (OR=1.59, 95% CI: 1.36 to 1.86, p<0.01) in the SB study. This effect was not observed in the PA study. Furthermore, time in the study did not significantly impact the odds of participants confirming to be sedentary (OR=0.97, 95% CI: 0.92 to 1.02, p=0.28). However, it significantly influenced the odds of confirming PA (OR: 0.81, 95% CI: 0.68 to 0.97, p=0.02), with the likelihood of confirming decreasing by 19% with each additional day in the study. Furthermore, a one-minute increase in latency (ie, time between last syncing and starting the EMA survey) in the PA study decreased the odds of the participant confirming to be physically active by 20% (OR: 0.80, 95% CI: 0.72 to 0.89, p<0.01). Simulations of the specific EMA settings revealed that reducing the event duration and shorter minimum time intervals between prompts increased the number of EMA surveys. Overall, most participants found smartphone usage to be feasible and rated the HealthReact app as user-friendly. However, some reported issues, such as not hearing the notification, receiving prompts at an inappropriate time and encountering technical issues. While the majority reported that their behaviour remained unchanged due to study participation, some noted an increased awareness of their habits and felt more motivated to engage in PA. CONCLUSIONS: This study demonstrates the potential of sensor-triggered EMA to capture real-time data on PA and SB among older adults, showing strong adherence potential with compliance rates of approximately 80%. The SB study had lower confirmation rates than the PA study, due to technical issues and discrepancies between self-perception and device-based measurements. Practical recommendations were provided for future studies, including improvements in survey timing, technical reliability and strategies to reduce latency.

Department of Public Health and Primary Care Ghent University Gent Belgium

Faculty of Physical Education and Sport Charles University Praha Czech Republic

Faculty of Science University of Hradec Kralove Hradec Kralove Czech Republic

Physical Activity and Health Department of Movement and Sports Sciences Ghent University Gent Belgium

Research Foundation Flanders Brussels Belgium

Université Libre de Bruxelles Bruxelles Belgium

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Dunstan DW, Barr ELM, Healy GN, et al. Television viewing time and mortality: the Australian Diabetes, Obesity and Lifestyle Study (AusDiab) Circulation. 2010;121:384–91. doi: 10.1161/CIRCULATIONAHA.109.894824. PubMed DOI

Knowler WC, Barrett-Connor E, Fowler SE, et al. Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. N Engl J Med. 2002;346:393–403. doi: 10.1056/NEJMoa012512. PubMed DOI PMC

Mammen G, Faulkner G. Physical activity and the prevention of depression: a systematic review of prospective studies. Am J Prev Med. 2013;45:649–57. doi: 10.1016/j.amepre.2013.08.001. PubMed DOI

Jefferis BJ, Sartini C, Lee I-M, et al. Adherence to physical activity guidelines in older adults, using objectively measured physical activity in a population-based study. BMC Public Health. 2014;14:382. doi: 10.1186/1471-2458-14-382. PubMed DOI PMC

World Health Organization . WHO guidelines on physical activity and sedentary behaviour. Geneva: World Health Organization; 2020.

Rosenberg D, Walker R, Greenwood-Hickman MA, et al. Device-assessed physical activity and sedentary behavior in a community-based cohort of older adults. BMC Public Health. 2020;20:1256. doi: 10.1186/s12889-020-09330-z. PubMed DOI PMC

Jefferis BJ, Sartini C, Shiroma E, et al. Duration and breaks in sedentary behaviour: accelerometer data from 1566 community-dwelling older men (British Regional Heart Study) Br J Sports Med. 2015;49:1591–4. doi: 10.1136/bjsports-2014-093514. PubMed DOI PMC

de Rezende LFM, Rey-López JP, Matsudo VKR, et al. Sedentary behavior and health outcomes among older adults: a systematic review. BMC Public Health. 2014;14:333. doi: 10.1186/1471-2458-14-333. PubMed DOI PMC

Ekelund U, Tarp J, Steene-Johannessen J, et al. Dose-response associations between accelerometry measured physical activity and sedentary time and all cause mortality: systematic review and harmonised meta-analysis. BMJ. 2019;366:l4570. doi: 10.1136/bmj.l4570. PubMed DOI PMC

Katzmarzyk PT, Powell KE, Jakicic JM, et al. Sedentary Behavior and Health: Update from the 2018 Physical Activity Guidelines Advisory Committee. Med Sci Sports Exerc. 2019;51:1227–41. doi: 10.1249/MSS.0000000000001935. PubMed DOI PMC

Wilmot EG, Edwardson CL, Achana FA, et al. Sedentary time in adults and the association with diabetes, cardiovascular disease and death: systematic review and meta-analysis. Diabetologia. 2012;55:2895–905. doi: 10.1007/s00125-012-2677-z. PubMed DOI

Thyfault JP, Du M, Kraus WE, et al. Physiology of sedentary behavior and its relationship to health outcomes. Med Sci Sports Exerc. 2015;47:1301–5. doi: 10.1249/MSS.0000000000000518. PubMed DOI PMC

Hardeman W, Houghton J, Lane K, et al. A systematic review of just-in-time adaptive interventions (JITAIs) to promote physical activity. Int J Behav Nutr Phys Act. 2019;16:31. doi: 10.1186/s12966-019-0792-7. PubMed DOI PMC

Stone AA, Shiffman S. Ecological Momentary Assessment (Ema) in Behavioral Medicine. Ann Behav Med. 1994;16:199–202. doi: 10.1093/abm/16.3.199. DOI

Shiffman S, Stone AA, Hufford MR. Ecological momentary assessment. Annu Rev Clin Psychol. 2008;4:1–32. doi: 10.1146/annurev.clinpsy.3.022806.091415. PubMed DOI

Dunton GF. Ecological Momentary Assessment in Physical Activity Research. Exerc Sport Sci Rev. 2017;45:48–54. doi: 10.1249/JES.0000000000000092. PubMed DOI PMC

Perski O, Keller J, Kale D, et al. Understanding health behaviours in context: A systematic review and meta-analysis of ecological momentary assessment studies of five key health behaviours. Health Psychol Rev. 2022;16:576–601. doi: 10.1080/17437199.2022.2112258. PubMed DOI PMC

Kraft R, Reichert M, Pryss R. Mobile Crowdsensing in Ecological Momentary Assessment mHealth Studies: A Systematic Review and Analysis. Sensors (Basel) 2024;24:472. doi: 10.3390/s24020472. PubMed DOI PMC

Degroote L, DeSmet A, De Bourdeaudhuij I, et al. Content validity and methodological considerations in ecological momentary assessment studies on physical activity and sedentary behaviour: a systematic review. Int J Behav Nutr Phys Act. 2020;17:35. doi: 10.1186/s12966-020-00932-9. PubMed DOI PMC

Giurgiu M, Niermann C, Ebner-Priemer U, et al. Accuracy of Sedentary Behavior-Triggered Ecological Momentary Assessment for Collecting Contextual Information: Development and Feasibility Study. JMIR Mhealth Uhealth. 2020;8:e17852. doi: 10.2196/17852. PubMed DOI PMC

Ebner-Priemer UW, Koudela S, Mutz G, et al. Interactive Multimodal Ambulatory Monitoring to Investigate the Association between Physical Activity and Affect. Front Psychol. 2012;3:596. doi: 10.3389/fpsyg.2012.00596. PubMed DOI PMC

Wrzus C, Neubauer AB. Ecological Momentary Assessment: A Meta-Analysis on Designs, Samples, and Compliance Across Research Fields. Assessment. 2023;30:825–46. doi: 10.1177/10731911211067538. PubMed DOI PMC

Courvoisier DS, Eid M, Lischetzke T. Compliance to a cell phone-based ecological momentary assessment study: the effect of time and personality characteristics. Psychol Assess. 2012;24:713–20. doi: 10.1037/a0026733. PubMed DOI

Williams MT, Lewthwaite H, Fraysse F, et al. Compliance With Mobile Ecological Momentary Assessment of Self-Reported Health-Related Behaviors and Psychological Constructs in Adults: Systematic Review and Meta-analysis. J Med Internet Res . 2021;23:e17023. doi: 10.2196/17023. PubMed DOI PMC

Wang S, Intille S, Ponnada A, et al. Investigating Microtemporal Processes Underlying Health Behavior Adoption and Maintenance: Protocol for an Intensive Longitudinal Observational Study. JMIR Res Protoc. 2022;11:e36666. doi: 10.2196/36666. PubMed DOI PMC

Compernolle S, Vetrovsky T, Maes I, et al. Older adults’ compliance with mobile ecological momentary assessments in behavioral nutrition and physical activity research: pooled results of four intensive longitudinal studies and recommendations for future research. Int J Behav Nutr Phys Act. 2024;21:92. doi: 10.1186/s12966-024-01629-z. PubMed DOI PMC

Ringeval M, Wagner G, Denford J, et al. Fitbit-Based Interventions for Healthy Lifestyle Outcomes: Systematic Review and Meta-Analysis. J Med Internet Res. 2020;22:e23954. doi: 10.2196/23954. PubMed DOI PMC

Hickey AM, Freedson PS. Utility of Consumer Physical Activity Trackers as an Intervention Tool in Cardiovascular Disease Prevention and Treatment. Prog Cardiovasc Dis. 2016;58:613–9. doi: 10.1016/j.pcad.2016.02.006. PubMed DOI

Delobelle J, Lebuf E, Dyck DV, et al. Fitbit’s accuracy to measure short bouts of stepping and sedentary behaviour: validation, sensitivity and specificity study. Digit Health. 2024;10:20552076241262710. doi: 10.1177/20552076241262710. PubMed DOI PMC

Sutton S, French DP, Hennings SJ, et al. Eliciting salient beliefs in research on the theory of planned behaviour: The effect of question wording. Curr Psychol . 2003;22:234–51. doi: 10.1007/s12144-003-1019-1. DOI

Wolcott MD, Lobczowski NG. Using cognitive interviews and think-aloud protocols to understand thought processes. Curr Pharm Teach Learn. 2021;13:181–8. doi: 10.1016/j.cptl.2020.09.005. PubMed DOI

Bates D, Mächler M, Bolker B, et al. Fitting Linear Mixed-Effects Models Usinglme4. J Stat Softw. 2015;67 doi: 10.18637/jss.v067.i01. DOI

Cain AE, Depp CA, Jeste DV. Ecological momentary assessment in aging research: a critical review. J Psychiatr Res. 2009;43:987–96. doi: 10.1016/j.jpsychires.2009.01.014. PubMed DOI PMC

Conroy DE, Maher JP, Elavsky S, et al. Sedentary behavior as a daily process regulated by habits and intentions. Health Psychol. 2013;32:1149–57. doi: 10.1037/a0031629. PubMed DOI PMC

Ten Broeke P, Gardner B, Beckers DGJ, et al. Why do people sit? A framework for targeted behavior change. Health Psychol Rev. 2023;17:641–54. doi: 10.1080/17437199.2022.2143851. PubMed DOI

Hernandez R, Schneider S, Pinkham AE, et al. Comparisons of Self-Report With Objective Measurements Suggest Faster Responding but Little Change in Response Quality Over Time in Ecological Momentary Assessment Studies. Assessment. 2025;32:335–55. doi: 10.1177/10731911241245793. PubMed DOI

Janek M, Kuhnova J, Cardon G, et al. Ecological momentary assessment of physical and eating behaviours: The WEALTH feasibility and optimisation study with recommendations for large-scale data collection. PLoS One . 2025;20:e0318772. doi: 10.1371/journal.pone.0318772. PubMed DOI PMC

Ram N, Brinberg M, Pincus AL, et al. The Questionable Ecological Validity of Ecological Momentary Assessment: Considerations for Design and Analysis. Res Hum Dev. 2017;14:253–70. doi: 10.1080/15427609.2017.1340052. PubMed DOI PMC

Balbim GM, Marques IG, Marquez DX, et al. Using Fitbit as an mHealth Intervention Tool to Promote Physical Activity: Potential Challenges and Solutions. JMIR Mhealth Uhealth. 2021;9:e25289. doi: 10.2196/25289. PubMed DOI PMC

Cimler R. HealthReact. 2024. https://www.healthreact.eu Available.

Vetrovsky T, Kral N, Pfeiferova M, et al. mHealth intervention delivered in general practice to increase physical activity and reduce sedentary behaviour of patients with prediabetes and type 2 diabetes (ENERGISED): rationale and study protocol for a pragmatic randomised controlled trial. BMC Public Health. 2023;23:613. doi: 10.1186/s12889-023-15513-1. PubMed DOI PMC

Elavsky S, Jandačková V, Knapová L, et al. Physical activity in an air-polluted environment: behavioral, psychological and neuroimaging protocol for a prospective cohort study (Healthy Aging in Industrial Environment study - Program 4) BMC Public Health. 2021;21:126. doi: 10.1186/s12889-021-10166-4. PubMed DOI PMC

Wealth. 2024. https://wealth-stamify.com Available.

Knapova L, Cho YW, Chow S-M, et al. From intention to behavior: Within- and between-person moderators of the relationship between intention and physical activity. Psychol Sport Exerc. 2024;71:S1469-0292(23)00190-5. doi: 10.1016/j.psychsport.2023.102566. PubMed DOI

Cajita MI, Rathbun SL, Shiffman S, et al. Examining reactivity to intensive longitudinal ecological momentary assessment: 12-month prospective study. Eat Weight Disord . 2023;28 doi: 10.1007/s40519-023-01556-1. PubMed DOI PMC

Song MK, Ward SE. Assessment effects in educational and psychosocial intervention trials: an important but often-overlooked problem. Res Nurs Health. 2015;38:241–7. doi: 10.1002/nur.21651. PubMed DOI PMC

Liao Y, Skelton K, Dunton G, et al. A Systematic Review of Methods and Procedures Used in Ecological Momentary Assessments of Diet and Physical Activity Research in Youth: An Adapted STROBE Checklist for Reporting EMA Studies (CREMAS) J Med Internet Res. 2016;18:e151. doi: 10.2196/jmir.4954. PubMed DOI PMC

O’Brien MW, Kivell MJ, Wojcik WR, et al. Influence of Anthropometrics on Step-Rate Thresholds for Moderate and Vigorous Physical Activity in Older Adults: Scientific Modeling Study. JMIR Aging . 2018;1:e12363. doi: 10.2196/12363. PubMed DOI PMC

Weber J, Angerer P, Apolinário-Hagen J. Physiological reactions to acute stressors and subjective stress during daily life: A systematic review on ecological momentary assessment (EMA) studies. PLoS One. 2022;17:e0271996. doi: 10.1371/journal.pone.0271996. PubMed DOI PMC

Delobelle J, Compernolle S, Vetrovsky T, et al. Contexts, affective and physical states and their variations during physical activity in older adults: an intensive longitudinal study with sensor-triggered event-based ecological momentary assessments. Int J Behav Nutr Phys Act. 2025;22:30.:30. doi: 10.1186/s12966-025-01724-9. PubMed DOI PMC

Carpenter C, Yang C-H, West D. A Comparison of Sedentary Behavior as Measured by the Fitbit and ActivPAL in College Students. Int J Environ Res Public Health. 2021;18:3914. doi: 10.3390/ijerph18083914. PubMed DOI PMC

Redenius N, Kim Y, Byun W. Concurrent validity of the Fitbit for assessing sedentary behavior and moderate-to-vigorous physical activity. BMC Med Res Methodol. 2019;19:29. doi: 10.1186/s12874-019-0668-1. PubMed DOI PMC

Wang SD, Hatzinger L, Morales J, et al. Burden and Inattentive Responding in a 12-Month Intensive Longitudinal Study: Interview Study Among Young Adults. JMIR Form Res . 2024;8:e52165. doi: 10.2196/52165. PubMed DOI PMC

Myin-Germeys I, Kuppens P. The Open Handbook of Experience Sampling Methodology: A Step-by-step Guide to Designing, Conducting, and Analyzing ESM Studies: Center for Research on Experience Sampling and Ambulatory Methods Leuven (REAL) 2021.