Wearable device-based short exercise breaks for improving activity patterns and body composition in adolescents with obesity

ISRCTN	ISRCTN16633553
DOI	https://doi.org/10.1186/ISRCTN16633553
Sponsor	Shandong Sport University
Funder	Investigator initiated and funded

Submission date: 27/06/2026
Registration date: 30/06/2026
Last edited: 29/06/2026

Recruitment status: No longer recruiting
Overall study status: Completed
Condition category: Nutritional, Metabolic, Endocrine

Prospectively registered

Protocol

Statistical analysis plan

Results

Individual participant data

Record updated in last year

Plain English summary of protocol

Background and study aims
Adolescent obesity is an important public health problem. Many adolescents find it difficult to complete long structured exercise sessions because of school schedules, limited time, low motivation, or limited access to exercise facilities. Exercise snacking is an alternative approach in which short bouts of physical activity are performed several times during the day. This study aims to assess whether wearable device-supported exercise snacking can improve daily activity patterns, body composition, physical activity, metabolic health, and psychological outcomes in adolescents with obesity.

Who can participate?
Adolescents aged 12–16 years with obesity can participate. Obesity is defined as BMI at or above the 95th percentile for age and sex. Participants must have stable school enrolment, no systematic exercise programme in the previous 6 months, and no diagnosed metabolic, cardiovascular, or neurological disorders. Written informed consent from a parent or legal guardian and written assent from the adolescent are required.

What does the study involve?
A total of 120 adolescents are randomly allocated to one of three groups. The first group receives wearable device-based exercise snacking with real-time feedback and prompts. The second group performs the same exercise snacking programme but without wearable feedback or prompts. The third group receives health education only. The active intervention lasts 12 weeks, followed by a 12-week no-contact follow-up period. The exercise snacking programme consists of brief body-weight or stepping-based activities lasting 1–3 minutes per bout, performed 5–8 times per day. Study outcomes are assessed at baseline, week 6, week 12, and week 24.

What are the possible benefits and risks of participating?
Participants may benefit from increased physical activity, improved daily activity patterns, better body composition, and improved awareness of healthy lifestyle behaviours. The risks are expected to be low. Possible risks include temporary tiredness, muscle soreness, minor discomfort during exercise, or discomfort from wearing monitoring devices. Participants are monitored during the study, and any adverse events are recorded.

Where is the study run from?
Shandong Sport University (China)

When is the study starting and how long is it expected to run for?
September 2025 to June 2026

Who is funding the study?
Investigator initiated and funded

Who is the main contact?
Dr Gang Qin, qingang@hanyang.ac.kr

Contact information

Dr Gang Qin
Public, Scientific, Principal investigator

Department of Sports Science, Hanyang University
Seoul
04763
Korea, South

ORCID ID	0009-0000-4147-2870
Phone	+82 (0)1056135210
Email	qingang@hanyang.ac.kr

Study information

Primary study design	Interventional
Allocation	Randomized controlled trial
Masking	Open (masking not used)
Control	Active
Assignment	Parallel
Purpose	Prevention
Scientific title	Effects of a wearable device-based exercise snacking intervention on daily activity fragmentation and body composition in adolescents with obesity: a randomized controlled trial
Study objectives
Ethics approval(s)	Approved 25/12/2024, Ethics Committee of Sport Science of Shandong Sport University (Shandong Sport University, No. 399 Shandong Road, Rizhao, 276826, China; +86 (0)13563345184; houyun@sdpei.edu.cn), ref: 2024083
Health condition(s) or problem(s) studied	Adolescent obesity and related body composition, physical activity, and metabolic health outcomes
Intervention	This is a three-arm randomized controlled trial involving adolescents aged 12–16 years with obesity. After completion of baseline assessment, eligible participants were randomly allocated in a 1:1:1 ratio to one of the following three groups: wearable device-based exercise snacking with real-time feedback, exercise snacking without feedback, or health education control. The randomisation sequence was generated by computer using permuted blocks with a block size of 6. Randomisation was stratified by sex and baseline BMI category to help ensure balanced allocation across groups. Allocation concealment was maintained using sequentially numbered, opaque, sealed envelopes prepared by an independent statistician who was not involved in participant recruitment, intervention delivery, or outcome assessment. The active intervention lasted 12 weeks, followed by a 12-week no-contact follow-up period. Participants in the two exercise snacking groups performed brief bouts of body-weight or stepping-based activity lasting 1–3 minutes per bout, 5–8 bouts per day.
Intervention type	Behavioural
Primary outcome measure(s)	Activity Fragmentation Index measured using the number of active-to-sedentary transitions per waking hour using ActiGraph GT9X accelerometer data processed with the GGIR package at baseline, week 6, week 12, and week 24
Key secondary outcome measure(s)	1. Moderate-to-vigorous physical activity is measured as minutes per day using ActiGraph GT9X accelerometer data processed with the GGIR package at baseline, week 6, week 12, and week 24. 2. Daily step count is measured using ActiGraph GT9X accelerometer data processed with the GGIR package at baseline, week 6, week 12, and week 24. 3. Sedentary time is measured as minutes per day using ActiGraph GT9X accelerometer data processed with the GGIR package at baseline, week 6, week 12, and week 24. 4. Body fat percentage is measured using dual-energy X-ray absorptiometry at baseline, week 12, and week 24. 5. Fat-free mass is measured using dual-energy X-ray absorptiometry at baseline, week 12, and week 24. 6. BMI percentile is calculated from measured height and body mass using WHO age- and sex-specific growth references at baseline, week 12, and week 24. 7. Waist-to-hip ratio is measured using an anthropometric tape at baseline, week 12, and week 24. 8. Resting metabolic rate is measured using indirect calorimetry with the Cosmed Quark CPET system at baseline, week 12, and week 24. 9. Respiratory exchange ratio is measured using indirect calorimetry with the Cosmed Quark CPET system at baseline, week 12, and week 24. 10. Heart rate variability, including SDNN and RMSSD, is measured using a Polar H10 heart rate monitor and Kubios HRV software at baseline, week 6, week 12, and week 24. 11. Resting heart rate is measured using a Polar H10 heart rate monitor at baseline, week 6, week 12, and week 24. 12. Fasting glucose is measured from fasting venous blood samples using the hexokinase method at baseline, week 12, and week 24. 13. Fasting insulin is measured from fasting venous blood samples using chemiluminescent immunoassay at baseline, week 12, and week 24. 14. Insulin resistance is measured using the homeostatic model assessment of insulin resistance, calculated from fasting glucose and fasting insulin, at baseline, week 12, and week 24. 15. Adiponectin is measured from fasting venous blood samples using enzyme-linked immunosorbent assay at baseline, week 12, and week 24. 16. Exercise motivation is measured using the Behavioral Regulation in Exercise Questionnaire-3 at baseline, week 6, week 12, and week 24. 17. Subjective well-being is measured using the World Health Organization Five Well-Being Index at baseline, week 6, week 12, and week 24. 18. Perceived exertion is measured using the Borg Rating of Perceived Exertion scale in the two exercise snacking groups at week 6 and week 12. 19. Intervention adherence is measured using automated app-recorded exercise completion rates in the wearable feedback group and weekly exercise logs in the exercise snacking without feedback group at week 6 and week 12. 20. Device wear time is measured using ActiGraph GT9X accelerometer data at baseline, week 6, week 12, and week 24.
Completion date	01/06/2026

Eligibility

Participant type(s)
Age group	Child
Lower age limit	12 Years
Upper age limit	16 Years
Sex	All
Target sample size at registration	120
Total final enrolment	120
Key inclusion criteria	1. Adolescents aged 12–16 years 2. BMI at or above the 95th percentile for age and sex according to WHO growth reference standards 3. Had not participated in a systematic exercise program within the preceding 6 months 4. Had stable school enrollment 5. Had no diagnosed metabolic, cardiovascular, or neurological disorders 6. Provided written assent with written informed consent from a parent or legal guardian
Key exclusion criteria	1. Currently using medications affecting metabolism or body composition, such as corticosteroids, thyroid hormones, or weight-loss pharmacotherapy 2. Diagnosed psychiatric conditions that could impair protocol adherence 3. Unable or unwilling to wear monitoring devices 4. Participating in concurrent weight-management programs 5. Metabolic, cardiovascular, or neurological disorders 6. Exercise contraindications 7. Judged during screening to have anticipated poor compliance
Date of first enrolment	01/09/2025
Date of final enrolment	31/12/2025

Locations

Countries of recruitment

China

Study participating centres

Results and Publications

Individual participant data (IPD) Intention to share	Yes
IPD sharing plan	De-identified individual participant data supporting the main study findings will be made available upon reasonable request after publication of the main results. Data will be shared only after approval by the study investigators and in accordance with ethics approval, participant consent, and applicable data protection requirements.