Exploring the Impact of Pacing on Physiological and Perceptual Responses in High Intensity Interval Training

Abstract

Purpose: To investigate the acute physiological effects and perceptual responses between fast-start (FS), even-strategy (ES) and slow-start (SS) pacing during a high-intensity interval training (HIIT) session.

Methods: Seven female (maximal oxygen uptake [VO2max] = 57 ± 3 ml·kg-1·min-1) and eight male (VO2max = 65 ± 2 ml·kg-1·min-1) well-trained athletes performed a total of 3 HIIT sessions 5 x 5 min, 2.5 min rest) with either FS, ES and SS, measuring rate of perceived exertion (RPE), heart rate (HR) and oxygen uptake (VO2). In FS, the first interval was 10 % lower than average velocity, followed by 5 % lower in the second interval. In the third interval velocity was set at 0 % (average velocity from familiarization), fourth interval had 5 % increase and the fifth had 10 % increase in velocity. ES consisted of an evenly pace at average velocity throughout the HIIT session, and SS had the same structure as FS only opposite, increasing from the slowest to the highest velocity.

Results: SS induced longer time in > 90 % VO2max compared to FS and ES (30 %, 26 % and 24 %, respectively). SS had the highest peak oxygen uptake (VO2peak), followed by FS where both was significantly higher than ES (60.1, 59.1 and 56.2 ml·kg-1·min-1, respectively) (p < .001). SS also resulted in highest peak heart rate (HRpeak) compared to FS and ES (p < .001). FS induced higher RPE in the speed matched interval compared to ES (p = .001) and SS (p = .03), and peak RPE (RPEpeak) was significantly higher in SS compared to FS and ES (p < .001). There was no significant difference between FS, ES or SS in average VO2, VO2 in the speed matched interval, average HR, average RPE or session RPE (sRPE).

Conclusion: SS gave more time at > 90 % VO2max combined with higher VO2peak, followed by FS and ES. FS showed higher sRPE, average RPE and average RPE in the speed matched interval compared to SS and ES. Despite these findings, there was no significant difference between average VO2, HR or RPE during HIIT sessions in this study.