Purpose: This study examined how projecting heart rate (HR) monitor data onto a screen acutely affected exercise intensity of intermediate aged school children during a class-based high-intensity interval training (HIIT).

Method: Twenty school students (12.3土0.87, M=8, F=12) from one school volunteered to participate in eight short HIIT sessions twice weekly, over a 4-week period. Sessions were delivered in class time by their teacher, and were conducted with or without the projection of HR data in a randomised order. Students wore HR monitors and their teacher suggested that they attempt to reach and sustain the HR target (>90% maximum) during the work bouts. The Polar GoFit™ application collected peak heart rate and percentage of time spent >90% maximum data (RED) during both projection and non-projection phases. Data were analysed using a repeated measure mixed model analysis of variance (ANOVA) with a compound symmetry covariance structure. Five short focus group interviews were completed with 17 students and two teachers at the end of the four weeks to gain perceptions on the influence of projection of HR monitor data on the sessions.

Results: A significant interaction was shown between group and projection condition for peak HR (p=0.011), and RED (p=0.001). No additional group effect was found between Group 1 and Group 2 across the three outcome measures. A significant difference was shown overall between projection and non-projection of the HR monitor data for peak HR (p=0.005), and RED (p=0.002). Focus group data confirmed that projection improved student motivation to achieve RED. Students described how projection ignited competition amongst their peers and provided accountability to work harder.

Conclusion: Projecting heart data onto a screen can increase the acute exercise intensity of intermediate aged school children during classroom based HIIT.