Influence of continuous and interval training on oxygen uptake on-kinetics

Purpose: To examine the relative effectiveness of moderate-intensity continuous training and high-intensity interval training on pulmonary O-2 uptake (VO2) kinetics at the onset of moderate- and severe-intensity cycle exercise in previously sedentary subjects. Methods: Twenty-three healthy subjects (I I males; mean +/- SD age 24 +/- 5 yr; VO2peak 34.3 +/- 5.5 mL(.)kg(-1.)min(-1)) were assigned to one of three groups: a continuous training group that completed three to four sessions per week of 30-min duration at 60% VO2peak (LO); an interval training group that completed three to four sessions per week involving 20 x 1-min exercise bouts at 90% VO2peak separated by 1-min rest periods (HI); or a control group (CON). Before and after the 6-wk intervention period, all subjects completed a series of step exercise tests to moderate and severe work rates during which pulmonary VO2 was measured breath-by-breath. Results: ANOVA revealed that continuous and interval training were similarly effective in reducing the phase II VO2 time constant during moderate (LO: from 31 +/- 8 to 23 +/- 5 s; HI: from 32 +/- 9 to 21 +/- 4 s; both P < 0.05; CON: from 30 +/- 6 to 29 +/- 7 s; NSD) and severe exercise (LO: from 35 +/- 6 to 24 +/- 7 s; HI: from 32 +/- 11 to 24 +/- 7 s; both P < 0.05; CON: from 27 +/- 7 to 25 +/- 5 s; NSD) and in reducing the amplitude of the VO2 slow component (LO: from 0.38 +/- 0.10 to 0.29 +/- 0.09 L(.)min(-1); HI: from 0.41 +/- 0.28 to 0.30 +/- 0.28 L(.)min(-1); both P < 0.05; CON: from 0.54 +/- 0.22 to 0.66 +/- 0.38 L(.)min(-1); NSD). Conclusions: Six weeks of low-intensity continuous training and high-intensity interval training were similarly effective in enhancing VO2 on-kinetics following step transitions to moderate and severe exercise in previously untrained subjects.