Faster Insights: process evaluation of HIIT

This post summarises the PRO-HIIT process evaluation (published 30 June 2026) and explains why process evaluation is necessary to interpret school-based HIIT outcomes.

• PRO-HIIT was published 30 June 2026 and is registered as NCT06374732 (registered 18/04/2024).
• The trial planned 60 sessions per class but delivered a mean of ≈26.5 sessions (class counts 26, 25, 24, 31).
• Physiological intensity: average HR 146 bpm (71% HRmax) and mean peak HR 175 bpm (85% HRmax); session RPE mean = 5.
• A school-wide sports event caused cancellations from week 5 and session length adapted from 10 to 6–8 minutes to preserve effort and curriculum fit.

This mixed-methods process evaluation (PRO-HIIT) explained implementation fidelity, adaptations, barriers and facilitators alongside outcome data.

This mixed approach means evaluators and program teams cannot rely on effect sizes alone, they must link qualitative logs, focus-group transcripts, and session-level telemetry to interpret what worked, for whom, and why.

• Study snapshot: Published 30 June 2026; cluster RCT protocol registered NCT06374732 (registered 18/04/2024).
• Core qualitative inputs: teacher training logbooks plus three focus groups (9 students, 2–3 teachers).
• Practical problem: planned dose (60 sessions) vs delivered (mean ≈26.5), contextual interruptions drove the dose shortfall.

This section summarises PRO-HIIT methods and the pragmatic deviations observed during implementation.

PRO-HIIT embedded 6–10 minute HIIT into PE/PA lessons (March–June 2024) and implementation was evaluated against the MRC process-evaluation framework using 12 measures across three domains: implementation, mechanisms of impact, and context.

• Primary quantitative inputs: training logbooks, HR monitors (Polar Verity Sense for 10 participants/session), OMNI RPE scale.
• Primary qualitative inputs: teacher and student focus groups, transcripts transcribed in Chinese and translated to English for analysis.
• Main deviations: PA lesson sessions were largely cancelled from week 5 due to a school-wide sports event; session length adapted (10 → 6–8 min) to preserve effort and curriculum fit.

This seven-step workflow describes how to run a PRO-HIIT style process evaluation in Evidano.

Step 1: Centralize inputs, upload logbooks (CSV), HR exports, and focus-group audio to one project.

Step 2: Auto-transcribe and translate (if needed) using custom dictionaries for study terms and acronyms.

Step 3: Import a predefined MRC-aligned codebook and run AI-assisted coding across transcripts and free-text logs.

Step 4: Map session metadata to coded themes and compute cross-segment frequencies (by class, sex, week).

Step 5: Visualize: dose-delivered timelines, SAAFE compliance heatmaps, co-occurrence networks for barriers and facilitators.

Step 6: Interpret with AI chat over your project, ask targeted questions like 'Which barriers predict missed sessions in week 5? ' and get evidence-linked answers with quotes and timestamps.

Step 7: Export an audit-ready mixed-methods report with linked quotes, charts, and a reproducible analysis log for publication or stakeholder briefings.

PRO-HIIT (published 30 June 2026) shows how process evaluation explains implementation gaps (dose vs planned), fidelity signals, and practical adaptations that shaped outcomes.

• Try a pilot: import one class of logbooks plus two focus-group transcripts into Evidano and run the 7-step workflow above.
• Try Evidano for free.

Ethics note: this post is research-focused guidance, not clinical advice. For ethics and consent procedures refer to the PRO-HIIT paper and your institutional review board.

Read the original study: PLOS ONE and trial registration: ClinicalTrials.gov.