QUANTIFYING OXYGEN DEFICIT AND TOTAL

Abstract

Objectives: This study quantitatively explored the extent of anaerobic and total energy expenditure during an acute bout of HIIT due to the lack of an accurate non-invasive estimation of anaerobic energy expenditure. This quantification is aimed to both further physiological understanding of energy expenditure and provide a scientific basis for exercise prescription. Method: Six male participants undertook three protocols on an arm crank ergometer; a peak, constant exercise, and interval protocol. Three prediction methods were used to estimate energy expenditure; peak interpolation, 6 minute values (6- min), and 3 minute (3- min) values from constant exercise. These predicted values were then used to quantify oxygen deficit and thus relative aerobic and anaerobic components within the 32.5-min interval session which consisted of six, 2.5-min intervals at 80% Wpeak each interspersed with 2.5-min active recovery at 40% Wpeak. Data were analysed using a standard analysis of variance (ANOVA) and 2-way ANOVA with Bonferroni post-hoc, pairwise comparison tests where appropriate; presented as mean ± standard deviation. Results: The average anaerobic component per interval using the 3 prediction methods were 63.6 (92.4), 30.3 (34.2), and 129.2 (30.1) % for the peak, 3-min and 6-min estimations respectively. The extent of difference in the anaerobic component between 6-min and 3- min prediction methods was statistically significant (P<0.05). Conclusion: The results from this study suggests that by using either the peak or 3-min prediction methods underestimates energy expenditure in HIIT due to the large negative values of oxygen deficit and small anaerobic component found; thus using 6-min of constant exercise is a more accurate prediction method. It is also suggested that a substantial component of HIIT is anaerobic when using a 6-min bout of submaximal exercise to estimate total energy expenditure and is not to be ignored during studies that attempt to calculate total energy expenditure during HIIT exercise.