Acute physiological and perceptual responses to three modes of high-intensity interval training: the development of the BE@Work (Brief Exercise at Work) intervention

INTRODUCTION: BE@Work (Brief Exercise at Work) is a controlled trial examining the effects of workplace-based high-intensity interval training (HIIT) on health and fitness outcomes. Despite accumulating evidence that HIIT can improve aspects of cardiometabolic health (Gibala et al. 2012), the feasibility of conducting HIIT beyond laboratory settings is unclear. In preliminary focus groups conducted within BE@Work, employees reported a preference for a choice of activities, with stair climbing, stepping and boxing the preferred exercise modes. As such, we aimed to assess heart rate (HR) and ratings of perceived exertion (RPE) responses to prototype HIIT protocols based on these exercises and explore whether HR and RPE substantially differed across modes. METHODS: Using a randomised cross-over design, nine employees (five male; aged 38.8 ± 12.3 years; mean ± SD) took part in three exercise sessions (stair climbing, stepping, boxing). Participants completed four 60 s bouts, each interspersed with 75 s rest, and were encouraged to work maximally. Second-to-second HR was recorded via Polar A360 monitors. Peak HR for each bout was expressed as a percentage of participants’ age predicted maximal HR (%HRmax), with a high-intensity exercise criterion of ≥85% of age-predicted HRmax (Weston et al. 2014). Session RPE was collected via the Borg CR-10 scale. Using a linear mixed model, mean differences between exercise modes were derived, with magnitude-based inferences subsequently applied. Threshold values for minimal important differences were two percentage points for HR and one Arbitrary Unit for RPE. Given the pilot nature of the study and the small sample size, substantial effects were only declared clear when the probability likelihood for the effect was ≥75% (i.e., likely). RESULTS: Participants’ mean (± SD) peak HR (expressed as % age-predicted HRmax) were 87 ± 9% for stair climbing, 88 ± 6% for stepping and 85 ± 4% for boxing. Mean RPE was 8 ± 3 for stair climbing, 8 ± 3 for stepping and 6 ± 2 for boxing. There were no substantial between-mode differences in HR or RPE. CONCLUSION: All three exercise modes elicited physiological and perceptual responses indicative of high-intensity exercise, thus presenting viable options for workplace HIIT programmes. The lack of substantial differences between stair climbing, stepping and boxing protocols suggests these could be used interchangeably in a HIIT intervention, without potentially compromising the intensity of the exercise. These findings inform the design and implementation of BE@Work; an 8-week HIIT intervention for workplaces in Northeast England. References: Gibala MJ et al (2012) Journal Physiol, 590,1077-1084. Weston KS et al (2014). Br J Sports Med, 48,1227-34.