Heart Rate and Oxygen Uptake During Recovery from High-Intensity Interval Training: A Retrospective Analysis

Background: Increases in maximal oxygen uptake (V̇O2max) occur with high-intensity interval training (HIIT), partially due to an extended duration spent at or near maximal V̇O2 or heart rate (HRmax). HIIT induces a delay in HR and V̇O2 during exercise, leading to consistently high HR/V̇O2 values in recovery between intervals. Purpose: This study compared the V̇O2 and HR response between exercise and recovery to various cycling HIIT protocols using data from seven prior studies. Methods: Healthy, active men and women (N = 104, age and V̇O2max 24 ± 5 yr and 40 ± 7 mL/kg/min) underwent HIIT protocols having different durations (30–60 s), intensities (70–85 percent of maximal workload (%Wmax), and recovery periods (10–75 s). V̇O2, HR, and blood lactate concentration (BLa) were assessed. Results: Across studies, peak HR was equal to 90.7 ± 6.2% HRmax. Results showed no significant difference in mean HR (159 ± 14 vs. 160 ± 15 b/min, p = 0.48) or V̇O2 (1.97 ± 0.47 vs. 1.98 ± 0.48 L/min, p = 0.82) between exercise and recovery. Conclusions: These data show elevated V̇O2 and HR during recovery from HIIT, suggesting a substantial, sustained load on the cardiovascular system in recovery from interval exercise.