Two Minutes of Sprint-Interval Exercise Elicits 24-hr Oxygen Consumption Similar to That of 30 min of Continuous Endurance Exercise

Six weeks (3 times/wk) of sprint-interval training (SIT) or continuous endurance training (CET) promote body-fat losses despite a substantially lower training volume with SIT. In an attempt to explain these findings, the authors quantified VO2 during and after (24 h) sprint-interval exercise (SIE; 2 min exercise) vs. continuous endurance exercise (CEE; 30 min exercise). VO2 was measured in male students (n = 8) 8 times over 24 hr under 3 treatments (SIE, CEE, and control [CTRL, no exercise]). Diet was controlled. VO2 was 150% greater (p < .01) during CEE vs. SIE (87.6 +/- 13.1 vs. 35.1 +/- 4.4 L O-2; M +/- SD). The observed small difference between average exercise heart rates with CEE (157 +/- 10 beats/min) and SIE (149 +/- 6 beats/min) approached significance (p = .06), as did the difference in peak heart rates during CEE (166 +/- 10 beats/min) and SIE (173 +/- 6 beats/min; p = .14). Total O-2 consumed over 8 hr with CEE (263.3 +/- 30.2 L) was greater (p < .01) than both SW (224.2 +/- 15.3 L; p < .001) and CTRL (163.5 +/- 16.1 L; p < .001). Total O-2 with SIE was also increased over CTRL (p < .001). At 24 hr, both exercise treatments were increased (p < .001) vs. CTRL (CEE = 500.2 +/- 49.2; SIE = 498.0 +/- 29.4; CTRL = 400.2 +/- 44.6), but there was no difference between CEE and SIE (p = .99). Despite large differences in exercise VO2, the protracted effects of SIE result in a similar total VO2 over 24 hr vs. CEE, indicating that the significant body-fat losses observed previously with SIT are partially due to increases in metabolism postexercise.