Oxygen Uptake in Maximal Effort Constant Rate and Interval Running

This study investigated differences in average V˙O2 of maximal effort interval running to maximal effort constant rate running at lactate threshold matched for time. The average V˙O2 and distance covered of 10 recreational male runners (V˙O2 max: 4158 ± 390 mL·min−1) were compared between a maximal effort constant-rate run at lactate threshold (CRLT), a maximal effort interval run (INT) consisting of 2 min at V˙O2 max speed with 2 minutes at 50% of V˙O2 repeated 5 times, and a run at the average speed sustained during the interval run (CR submax). Data are presented as mean and 95% confidence intervals. The average V˙O2 for INT, 3451 (3269–3633) mL·min−1, 83% V˙O2 max, was not significantly different to CRLT, 3464 (3285–3643) mL·min−1, 84% V˙O2 max, but both were significantly higher than CR sub-max, 3464 (3285–3643) mL·min−1, 76% V˙O2 max. The distance covered was significantly greater in CLRT, 4431 (4202–3731) metres, compared to INT and CR sub-max, 4070 (3831–4309) metres. The novel finding was that a 20-minute maximal effort constant rate run uses similar amounts of oxygen as a 20-minute maximal effort interval run despite the greater distance covered in the maximal effort constant-rate run.