Physiological Responses and Role of VO2 slow Component to Interval Training with Different Intensities and Durations of Work.

Abstract

PURPOSE: The purpose of this study was to compare four interval training (IT) sessions with different intensities and durations of work in order to determine the effect on mean VO2, total VO2 for the exercise session and duration of exertion ≥ 90% maximum work rate (MWR), and the effects on biomarkers of fatigue such as blood lactate concentration (BLC) and rate of perceived exertion (RPE). A secondary objective was to determine the extent that the VO2 slow component plays in the total oxygen demand of IT. METHODS: Twelve competitive male and female triathletes between 18 and 35 years of age (mean age ± SD = 27.6 ± 4.3) were asked to perform four different IT protocols on a cycle ergometer with different intensities and durations of work. VO2 was measured every 30 seconds during all the IT sessions using a metabolic cart. Heart rate (HR) and RPE were measured at the end of every resting and work period, and BLC was measured every 10 min during the IT session. RESULTS: The three major findings were: 1) 90% MWR sessions produced higher values for total VO2 (L/min) and total time completed for each session (min) as compared to 100% of MWR sessions (P ≤ 0.001). 2) The 30 s interval durations produced higher values for total VO2 (L/min), total time completed for each session (min), mean VO2 (ml/kg/min) and HR (bpm) and lower BLC (P ≤ 0.01) as compared to the 3 min interval durations (P ≤ 0.001). 3) All IT protocols showed a significant (P ≤ 0.001) rise of VO2 (VO2 slow component) across the duration of each IT session. CONCLUSIONS: This study revealed that IT using 30 s duration intervals (30-30 s) allows the athlete to perform a longer session, with a higher total and mean VO2 and HR and lower BLC than 3 min duration. Similarly, submaximal exertion at 90% of MWR also allows performing longer sessions with a higher total VO2 than 100% intensity. All protocols showed a slow component effect in the total oxygen demands of IT.