Heart Rate And Rating Of Perceived Exertion During High-intensity Interval Training: Implications For Prescribing Intensity

High-intensity interval training (HIIT) is a popular and effective time-efficient alternative to moderate-intensity continuous training for improving cardiorespiratory fitness in a wide range of populations. However, there is limited research investigating the most effective and practical way to prescribe training intensities for HIIT. PURPOSE: To determine heart rate (HR) and rating of perceived exertion (RPE) responses across a single bout of HIIT. Additionally, the relationship between HR and RPE were examined. METHODS: Young adults (n=16; age 21.8±1.4 years; 10 females) visited the lab on two separate occasions. At the first visit, participants completed an incremental exercise test on a cycle ergometer to determine peak power output (PPO). Participants completed the HIIT session during their second lab visit. The HIIT protocol involved ten, 1-minute bouts of cycling at 80% PPO interspersed with 1-minute of active rest cycling at 20% PPO. HR and RPE were measured at the end of the first, fifth and tenth work interval. RPE was measured using the CR10 Borg scale. One-way repeated measures ANOVAs were used to determine HR and RPE responses across the HIIT session. Pearson correlations were utilized to assess relationships between HR and RPE. RESULTS: HR and RPE both significantly increased from the first (HR 157±16 bpm; RPE 5.0±1.8) to the fifth interval (HR 174±14 bpm; RPE 6.8±1.7; p<0.05 for both). However, there were no significant differences in HR or RPE between the fifth and tenth interval (180±12 bpm; RPE 7.7±1.9 p>0.05 for both). There were no significant relationships between HR and RPE for any of the time points (r=-0.01 to -0.34, p=0.19 to 0.89) or the average of the session (r=0.37, p=0.16). CONCLUSIONS: HR and RPE both increased initially during the HIIT session with no further increase after mid-point. There were no significant relationships between HR and RPE. These findings suggest that RPE, using the CR10 Borg scale, may not replicate HR for determining intensity during HIIT. Future research may be beneficial to determine a practical method for prescribing exercise intensity during HIIT. Further, it would be beneficial to examine the use of RPE and HR as methods of prescribing intensity in long-term, real-world intervention studies.