Oxygen Uptake in Maximal Effort Constant Rate and Interval Running

This study investigated differences in average (V) over dotO(2) of maximal effort interval running to maximal effort constant rate running at lactate threshold matched for time. The average (V) over dotO(2) and distance covered of 10 recreational male runners ((V) over dotO(2) (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) over dotO(2) (max) speed with 2 minutes at 50% of (V) over dotO(2) 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) over dotO(2) for INT, 3451 (3269-3633) mL.min(-1), 83% (V) over dotO(2) (max), was not significantly different to CRLT, 3464 (3285-3643) mL.min(-1), 84% (V) over dotO(2) (max), but both were significantly higher than CR sub-max, 3464 (3285-3643) mL.min(-1), 76% (V) over dotO(2 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.