Was it a HIIT? A process evaluation of a school-based high-intensity interval training intervention

Area of Science:

• School-based physical activity interventions
• High-Intensity Interval Training (HIIT) implementation science

Background:

• Limited process evaluations exist for school-based high-intensity interval training (HIIT) interventions.
• Process evaluations are crucial for interpreting outcomes and refining intervention design.
• This manuscript details a process evaluation of the Making a HIIT school-based intervention.

Purpose of the Study:

• To conduct a comprehensive process evaluation of the Making a HIIT intervention.
• To assess implementation factors including reach, dosage, fidelity, and adaptability.
• To gather insights for improving future school-based HIIT programs.

Main Methods:

• An 8-week mixed-methods process evaluation guided by the Framework for Effective Implementation.
• Intervention involved 10-min teacher-led HIIT workouts in health and physical education (HPE) lessons.
• Data collected on program reach, dosage, fidelity (time at ≥80% HRmax), student enjoyment, and teacher feedback.

Main Results:

• Successfully recruited 3 of 10 contacted schools, with 79% student consent (n=308).
• Average attendance was 6 out of 10 prescribed HIIT workouts; 55% of workout time was at ≥80% HRmax.
• Students reported neutral enjoyment (3.3/5); teachers found workouts simple but noted time implications and adaptability needs.

Conclusions:

• The Making a HIIT evaluation offers valuable insights into implementing school-based HIIT.
• Encouraging findings regarding student enjoyment and fidelity were observed.
• Recommendations for optimizing dosage and adaptability are crucial for future intervention development.