The effects of interval-exercise duration and intensity on oxygen consumption during treadmill running

The magnitude of improvement in peak oxygen uptake ((V) over dot(O2peak)) and performance to an exercise training regime is related to the (V) over dot(O2) of prior accumulated exercise training bouts. However, it is unclear whether constant rate training (CRT) or interval training (INT) preferentially alters the (V) over dot(O2) of running exercise. Therefore, the purpose of this study was to compare the acute (V) over dot(O2) response to constant, and interval training sessions. Consequently, this study compared the mean average (V) over dot(O2) of 17 moderately trained participants to a 20-min CRT and two different 20 min INT treadmill runs. Participants completed three treatments (twice) in random order over 3 weeks. In 1 min INT participants completed 10 x 1 min efforts at the velocity corresponding to (V) over dot(O2peak)(V-peak) interspersed with 10 x 1 min efforts at 0.5V(peak). In the 2 min INT, participants completed 5 x 2 min efforts at the V-peak interspersed with 5 x 2 min efforts at 0.5 at V-peak. In CRT participants ran at a velocity equivalent to the mean velocity of INT (75% V-peak). Mean average (V) over dot(O2) for 2 min INT, 1 min INT and CRT were, respectively, 3200 +/- 661; 3076 +/- 6041; 2909 +/- 584 ml min(-1). Both INT sessions resulted in a significantly higher mean average (V) over dot(O2) than CRT. Furthermore, 2 min INT resulted in 90% of (V) over dot(O2peak) being exceeded more frequently than 1 min INT We conclude that INT serves as a more potent stimulus for improvement in (V) over dot(O2peak) and subsequent endurance performance than CRT. (C) 2007 Sports Medicine Australia. Published by Elsevier Ltd. Ali rights reserved.