Shorter versus longer bouts of rowing-based interval exercise attenuate the physiological and perceptual response

High intensity interval exercise (HIIE) requires repeated bouts of near-maximal to maximal efforts (intensities \u3e 85 %HRmax) interspersed with a brief recovery. Data show superior increases in maximal oxygen uptake (VO 2max) in response to chronic HIIE compared to moderate intensity continuous exercise (MICE) in healthy adults as well as clinical populations (Milanovic et al. 2015; Weston et al., 2014). PURPOSE: This study compared physiological and perceptual variables between short and long durations of rowing-based high intensity interval exercise (HIIE). METHODS: Fourteen active adults (age = 26.4 ± 7.2 yr) performed incremental rowing exercise to fatigue to measure maximal oxygen uptake (VO 2max) and peak power output (PPO). The subsequent 20 min sessions required HIIE (eight 60 s efforts at 85 %PPO with 90 s of active recovery at 20 %PPO or 24 20 s efforts at 85 %PPO with 30 s of active recovery at 20 %PPO) or moderate intensity continuous exercise (MICE) at 40 %PPO. During exercise, VO 2, heart rate (HR), blood lactate concentration (BLa), rating of perceived exertion (RPE), and affective valence were measured. RESULTS: Data show significantly (p \u3c 0.001) higher peak VO 2 (84 ± 7 vs. 76 ± 5 %VO 2peak, d = 0.99), peak HR (94 ± 4 %HRpeak vs. 90 ± 4 %HRpeak, d = 1.12), BLa (7.0 ± 2.5 mM vs. 4.1 ± 1.0 mM, d = 1.22), end-exercise RPE (12.8 ± 2.0 vs. 11.0 ± 1.7, d = 1.29), and lower affective valence (2.1 ± 1.6 vs. 2.9 ± 1.2, d = 0.61) with long versus short HIIE. Time spent above 85 %HRpeak was significantly higher (p \u3c 0.001) in short versus long HIIE (606 ± 259 vs. 448 ± 26 s, d = 0.91). CONCLUSION: Longer rowing-based intervals elicit greater cardiometabolic and perceptual strain versus shorter efforts, making the latter preferable to optimize perceptual responses to HIIE