Grade-Specific Effects of Recess HIIT and MICT on Classroom Attention-Related Behavior in Primary School Children

Grade-Specific Effects of HIIT and MICT During School Recess on Observable Classroom Attention-Related Behavior in Primary School Children: A Randomized Controlled Trial

This randomized controlled trial evaluated whether structured exercise during school recess could improve observable classroom attention-related behavior in primary school children and whether the effects differed between grade levels.

A total of 144 third- and fifth-grade students were randomly assigned to one of three groups: high-intensity interval training (HIIT), moderate-intensity continuous training (MICT), or routine recess activity. The intervention lasted 6 weeks and was conducted three times per week during scheduled school recess. Each structured exercise session lasted 15 minutes, including warm-up, a 9-minute main exercise component, and cool-down.

Observable classroom attention-related behavior was assessed before and after the intervention using an automated video-based behavioral analysis system. The system evaluated observable indicators including head posture, eye gaze, eye opening or closing, and facial detection persistence. The study compared changes among the three groups and examined whether the effects of HIIT and MICT differed between third- and fifth-grade students.

Study Overview

• Status: Completed
• Conditions: Classroom Attention-Related Behavior; School-Based Physical Activity
• Intervention / Treatment: Behavioral: High-Intensity Interval Training During School Recess; Behavioral: Moderate-Intensity Continuous Training During School Recess

Detailed Description

This study used a randomized, pretest-posttest, three-arm controlled design to investigate the grade-specific effects of high-intensity interval training and moderate-intensity continuous training conducted during school recess on observable classroom attention-related behavior in primary school children.

Participants were third- and fifth-grade students recruited from a primary school in Shanghai, China. After baseline assessment, 144 eligible children were randomly allocated in a 1:1:1 ratio to the high-intensity interval training group, the moderate-intensity continuous training group, or the routine recess control group, with 48 participants in each group. Randomization was performed at the individual level using a computer-generated sequence and was stratified by grade and sex. The allocation sequence was generated by an independent researcher, and assignments were concealed in sequentially numbered, sealed opaque envelopes.

The study lasted 8 weeks. Week 1 included familiarization and baseline assessments. Weeks 2 through 7 comprised the formal 6-week intervention, and Week 8 included post-intervention assessment. The exercise interventions were delivered three times per week during scheduled school recess, for a total of 18 sessions.

Each structured exercise session lasted 15 minutes and consisted of a 3-minute preparatory activity, a 9-minute main exercise component, and a 3-minute cool-down. Exercise intensity was monitored in real time using heart rate monitors.

The high-intensity interval training group performed interval circuit exercises consisting of jumping jacks, cross jumps, vertical jumps, and burpees. Each exercise was performed for 30 seconds followed by 30 seconds of recovery. The target intensity during the main exercise component was at least 85% of age-predicted maximal heart rate.

The moderate-intensity continuous training group performed continuous aerobic running during the 9-minute main exercise component. The target intensity was maintained at 60% to 69% of age-predicted maximal heart rate.

The control group continued routine school recess activities without receiving additional structured exercise. Routine activities included walking, free play, standing rest, and other usual school-arranged recess behaviors.

The primary outcome was the change in observable classroom attention-related behavior from baseline to post-intervention. Classroom behavior was assessed using an automated video-based analysis system that extracted four observable indicators: head posture, eye gaze, eye opening or closing status, and facial detection persistence. These indicators were standardized and integrated into a composite score, with higher scores indicating greater consistency with classroom-oriented behavior.

The composite score was interpreted as an ecological proxy measure of observable classroom attention-related behavior rather than a direct measure of internal cognitive attention. The primary statistical analysis examined the effects of time, intervention group, grade level, and their interactions, with particular emphasis on the Time × Group × Grade interaction.

Because of the nature of the exercise interventions, participants and exercise instructors were not blinded. However, personnel responsible for video data processing and statistical analysis were not involved in intervention delivery and followed standardized assessment procedures.

• Study Type: Interventional
• Enrollment (Actual): 144
• Phase: Not Applicable

Contacts and Locations

Study Locations

• China
  • Shanghai Municipality
    • Shanghai, Shanghai Municipality, China, 200438
      • Shanghai University of Sport

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Students enrolled in the third or fifth grade at the participating primary school.
• Aged 8 to 12 years.
• Able to participate in routine physical education classes and school recess activities.
• Free from musculoskeletal injury or any medical condition that contraindicated participation in physical exercise.
• Written informed consent provided by a parent or legal guardian.
• Verbal assent provided by the participating child.
• Willing and able to complete the baseline assessment, exercise intervention, and post-intervention assessment.

Exclusion Criteria:

• Musculoskeletal injury, cardiovascular disease, respiratory disease, neurological disorder, or other medical condition that made participation in moderate- or high-intensity exercise unsafe.
• A diagnosed attention-deficit/hyperactivity disorder, autism spectrum disorder, anxiety disorder, depressive disorder, intellectual disability, or other psychological or developmental condition that could substantially affect participation or assessment of classroom attention-related behavior.
• Color blindness or another visual impairment that could interfere with the study assessments.
• Participation in a structured high-intensity exercise training program during the 3 months before enrollment.
• Regular participation in systematic extracurricular exercise training that could substantially affect the intervention response.
• Inability to complete the intervention or study assessments.
• Absence from three or more intervention sessions.
• Withdrawal of parental or guardian consent or withdrawal of the child's assent.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: High-Intensity Interval Training (HIIT) Group; Participants received a structured high-intensity interval training program during scheduled school recess for 6 weeks, three sessions per week, for a total of 18 sessions. Each 15-minute session included a 3-minute warm-up, a 9-minute HIIT component, and a 3-minute cool-down. The HIIT component consisted of jumping jacks, cross jumps, vertical jumps, and burpees. Each movement was performed for 30 seconds followed by 30 seconds of recovery. The sequence was completed twice, with a 1-minute rest between sets. The target intensity during the main exercise component was at least 85% of age-predicted maximal heart rate.	Behavioral: High-Intensity Interval Training During School Recess; Participants completed a structured high-intensity interval training program during scheduled school recess for 6 weeks, with three sessions per week and 18 sessions in total. Each 15-minute session included a 3-minute warm-up, a 9-minute main exercise component, and a 3-minute cool-down. The main component consisted of jumping jacks, cross jumps, vertical jumps, and burpees. Each movement was performed for 30 seconds followed by 30 seconds of recovery, using a 1:1 work-to-rest ratio. The sequence was completed twice, with a 1-minute rest between sets. Exercise intensity was monitored using heart rate monitors, and the target intensity during the main component was at least 85% of age-predicted maximal heart rate.
Active Comparator: Moderate-Intensity Continuous Training (MICT) Group; Participants received a structured moderate-intensity continuous training program during scheduled school recess for 6 weeks, three sessions per week, for a total of 18 sessions. Each 15-minute session included a 3-minute warm-up, 9 minutes of continuous aerobic running, and a 3-minute cool-down. The target intensity during the continuous running component was maintained at 60% to 69% of age-predicted maximal heart rate. Heart rate was monitored during each session to confirm adherence to the prescribed exercise intensity.	Behavioral: Moderate-Intensity Continuous Training During School Recess; Participants completed a structured moderate-intensity continuous training program during scheduled school recess for 6 weeks, with three sessions per week and 18 sessions in total. Each 15-minute session included a 3-minute warm-up, 9 minutes of continuous aerobic running, and a 3-minute cool-down. Exercise intensity was monitored using heart rate monitors, and the target intensity during the continuous running component was maintained at 60% to 69% of age-predicted maximal heart rate. Running speed and rhythm were adjusted according to real-time heart rate responses and participant tolerance.
No Intervention: Routine Recess Control Group; Participants continued the routine recess activities arranged by the school and received no additional structured exercise intervention. Routine activities included walking, free play, standing rest, and other usual unstructured or school-arranged recess behaviors. Participants followed the same school schedule as the two structured exercise groups and returned to classroom learning at the same time.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Composite Observable Classroom Attention-Related Behavior Score	Observable classroom attention-related behavior was assessed using an automated video-based behavioral analysis system. The system standardized the individual behavioral indicators and integrated them into a composite score. Higher scores indicate greater consistency with classroom-oriented behaviors, including instructional orientation, visual engagement, observable alertness, and maintenance of a classroom-facing position. The outcome was the change in the composite score from baseline to post-intervention.	Baseline and immediately after the 6-week intervention at Week 8

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Head Posture Score	Head posture was assessed using the automated video-based behavioral analysis system. The indicator reflects the participant's physical orientation toward instructional targets during classroom activities. The system generated a standardized head posture score, with higher scores indicating more consistent orientation toward instructional targets. The outcome was the change in the score from baseline to post-intervention.	Baseline and immediately after the 6-week intervention at Week 8
Change in Eye Gaze Score	Eye gaze was assessed using the automated video-based behavioral analysis system. The indicator reflects the participant's visual orientation toward classroom learning areas. The system generated a standardized eye gaze score, with higher scores indicating more sustained visual orientation toward classroom learning areas. The outcome was the change in the score from baseline to post-intervention.	Baseline and immediately after the 6-week intervention at Week 8
Change in Eye Opening and Closing Status Score	Eye opening and closing status was assessed using the automated video-based behavioral analysis system. This indicator reflects observable alertness-related behavior during classroom activities. The system generated a standardized score, with higher scores indicating greater consistency with an observable alert and eyes-open state. The outcome was the change in the score from baseline to post-intervention.	Baseline and immediately after the 6-week intervention at Week 8
Change in Facial Detection Persistence Score	Facial detection persistence was assessed using the automated video-based behavioral analysis system. This indicator reflects whether the participant maintained a detectable classroom-facing position during classroom activities. The system generated a standardized score, with higher scores indicating greater persistence of a detectable classroom-facing position. The outcome was the change in the score from baseline to post-intervention.	Baseline and immediately after the 6-week intervention at Week 8

Collaborators and Investigators

• Sponsor: Shanghai University of Sport

Study record dates

Study Major Dates

• Study Start (Actual): March 1, 2024
• Primary Completion (Actual): May 30, 2024
• Study Completion (Actual): May 30, 2024

Study Registration Dates

• First Submitted: July 17, 2026
• First Submitted That Met QC Criteria: July 17, 2026
• First Posted (Actual): July 22, 2026

Study Record Updates

• Last Update Posted (Actual): July 22, 2026
• Last Update Submitted That Met QC Criteria: July 17, 2026
• Last Verified: July 1, 2026

More Information

Terms related to this study

• Keywords: Physical Activity; High-Intensity Interval Training; Primary School Children; Moderate-Intensity Continuous Training; School Recess; Classroom Attention; Attention-Related Behavior; Grade-Specific Effects
• Additional Relevant MeSH Terms: Behavior; Motor Activity
• Other Study ID Numbers: 102772023RT094

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Individual participant data will not be shared because the study involves minors and includes video-derived behavioral data that may carry a risk of participant re-identification. De-identified aggregate results will be reported in scientific publications.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No