Fig. 3
From: Was it a HIIT? A process evaluation of a school-based high-intensity interval training intervention
A The average heart rate across all students and sessions during 1) the high-intensity interval training (HIIT) sessions for the HIIT group shown in grey; 2) the HPE lesson for the HIIT group shown in white; and 3) the HPE lesson for the control group shown in white. B The percentage of time students’ heart rate was equal to or greater than to 80% of their maximum heart rate across all students and sessions during 1) the high-intensity interval training (HIIT) sessions for the HIIT group shown in grey; 2) the HPE lesson for the HIIT group shown in white; and 3) the HPE lesson for the control group shown in white. HIIT = high-intensity interval training; HPE = Health and Physical Education